Kiri

European Union Aviation Safety Agency – EPAS Preparation

Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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Note: ¡Conspicuity (or in-flight electronic conspicuity plus) means in-flight capability to transmit position of aircraft and/or to receive, process and display positions of other aircraft in a real time with the objective to enhance pilots’ situational awareness about surrounding traffic. It is an umbrella term for a range of technologies and solutions, whether airborne or on the ground, that can help airspace users and other affected stakeholders to be more aware of other aircraft in their vicinity or in a given airspace. The ¡Conspicuity (concept) is expected to evolve in time thru the integration of new functionalities and sharing of additional aeronautical information in a real-time (like the weather or airspace related).

1 Why to intervene?

In 2020, the BIS Airborne collision risk concluded that that a broader use of ¡Conspicuity solutions and improvement of their interoperability together with a better airspace utilisation and design, while ensuring compatibility with U-space regulatory framework, should be at the heart of the strategy to define future actions.

While the BIS considered all aspects of risk (e.g. ATM and U-space perspectives) the proposed actions focused on the risk of collision involving smaller manned aircraft not subject to air traffic control. This was based on the 2020 safety analysis which concluded that only these aircraft were involved in airborne collisions with fatal consequences.

Safety data0F

1 from 2009 to 2019 indicated that there were 51 fatal accidents involving 117 fatalities (an average of 13 fatalities and six fatal collisions per year) caused by airborne collisions in EASA states during that period.

The 2020 BIS report led to the following actions introduced in the EPAS for the following Safety Issues.

EPAS actions The most relevant Safety Issues (SI) addressed by the actions SI-2025 Airspace

infringement SI-4010 Airborne separation / SI-0043

Deconfliction of IFR and VFR traffic SI-8028 Inadequate

airborne separation under VFR operation

MST.0038 Airspace complexity and traffic congestion

X X X

SPT.0119 Promoting ¡Conspicuity

X X X

SPT.0120 Promoting good practices in airspace design

X X X

RES.0031 Interoperability of different ¡Conspicuity devices/systems

X

RES.0032 Use of ¡Conspicuity devices/systems in flight information services

X

1 Note: the geographical scope of the safety data covers on EASA Member States (i.e. this does not cover UK compared to the information included in the BIS version in 2020). 10 fatal collisions and 20 fatalities that occurred in UK during the period 2009-2019 were deducted.

European Union Aviation Safety Agency – EPAS Preparation

Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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RMT.0690, RMT.0230, RMT.0519

x x x

See Annex 1 for the monitoring of the BIS 2020 actions.

The most recent data, covering the period from 2020 to 2024, revealed that there were 25 fatalities in nine fatal collisions during the last five years (an average of five fatalities and two fatal collisions per year). This substantial improvement in safety indicates that the strategy implemented in 2020 is effective.

The above-mentioned information together with outcomes of the actions indicates that the strategy to focus on a set of primarily non-regulatory actions (SPT and RES) complemented by existing regulatory tasks to provide minimum requirements1F

2 is confirmed. This together with utilisation of broadly available digital technologies contributed to noteworthy safety improvements in a relatively short period.

This supports the continuation of the implementation of the 2020 Strategy, with minor adaptations to incorporate the outcomes of completed actions and other initiatives undertaken since then:

• EASA and Eurocontrol jointly developed roadmap for the ¡Conspicuity (Annex 2), with the aim of enhancing situational awareness and safety for manned aircraft not under air traffic control. It proposes a simple, affordable, and interoperable system architecture based on the principles of "one language" (with ADS-L as the key enabler) and "one link" (a direct air-to-air radio link for pilot awareness, complemented by air-to-ground links). The strategy addresses three use cases: voluntary pilot situational awareness in any airspace, U-space airspace compliance and ATM (research). It leverages existing candidate technologies (ADS-B, 1090, UAT, SRD860, mobile networks) while acknowledging the diverse requirements of aviation communities. The implementation process will include progressive milestones from 2024 to 2027+, involving technology assessments, stakeholder engagement, and pilot-driven deployment;

• the recommendations from the SIA airspace infringement report (Annex 3);

• The ¡Conspicuity Declaration that is a voluntary policy jointly created by aviation authorities and industry stakeholders to promote the use of electronic conspicuity devices and related data—such as ADS-B, ADS-L and surveillance data—in the General Aviation (GA) sector. Its goal is to enhance

2 that are objective driven and proportionate to the nature of activity concerned.

0

50

100

150

2009-2019 2020-2024 2009-2024

Number of fatal collisions and related fatalities EASA MS - 2009 -

2024

Fatal collisions Fatalities

Significant reduction for

2020-2024

0.00 2.00 4.00 6.00 8.00

10.00 12.00

2009-2019 2020-2024 2009-2024

Annual fatal collisions average and average collision fatalities, EASA MS -

2009 - 2024

Average collisions per year Average fatalities per year

Significant reduction for

2020-2024

European Union Aviation Safety Agency – EPAS Preparation

Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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operational safety, foster a proactive safety culture, and support collaborative data analysis. The declaration emphasizes voluntary participation, system-wide insights, transparent monitoring, and compliance with data protection regulations. Expected benefits include reduced collision risk, improved airspace access, faster emergency response, and better incident analysis. Overall, it encourages safer and more efficient European airspace through data-driven collaboration;2F

3

• ADS-L technology is the key to making ¡Conspicuity a reality. EASA has partnered with industry and user associations to launch the ADS-L Coalition. It is a partnership where participants commit to taking ownership of the ADS-L and supporting its further development to enhance situational awareness for everyone, whether in the air or on the ground.2

2 BIS 2025 updated actions

The following relevant actions decided in the 2020 BIS (Annex 4) are extended to the period 2026-2028. This covers also the following aspects:

• The EASA and Eurocontrol joint roadmap for the ¡Conspicuity • Incorporation of recommendations from the Safety Issue Analysis “Airspace Infringement” with the

objective to prevent collisions caused by airspace infringement. • ¡Conspicuity Declaration • ADS-L Coalition

Legend: action with circle in white are proposed to be extended until 2028. RES tasks were delayed compared to the plan in BIS 2020 due to pandemic and associated reduction of resources for research.

¡Conspicuity cluster: the focus is on the technology and its use.

3https://www.easa.europa.eu/iconspicuity, https://www.easa.europa.eu/ads-l

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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Airspace cluster: the focus is on design and use of the airspace.

No additional actions are foreseen compared to the BIS 2020 version. The implementation and the monitoring of the actions will continue. A new BIS version is expected in the future with the relevant update.

3 Annexes

• Annex 1: Monitoring of BIS Airborne Collision 2020 actions • Annex 2: EASA/EUROCONTROL roadmap • Annex 3: Safety Issue Assessment “Airspace Infringement” • Annex 4: Link to the BIS report on Airborne Collision commented by the Advisory Bodies 2020:

Table of content of the BIS 2025 update

4 Annex 1: Monitoring of BIS Airborne Collision 2020 actions ...................................................................... 4 5 Annex 2: EASA/EUROCONTROL roadmap ................................................................................................. 13 6 Annex 3: Safety Issue Assessment “Airspace Infringement” .................................................................... 18 1 Safety Issue Assessment ........................................................................................................................... 20 2 Baseline scenario-– What would happen if there is no additional action? .............................................. 34 3 Intervention objectives ............................................................................................................................. 34 4 List of proposed actions and assessment of their integration in the BIS Airborne Collision .................... 34 5 Conclusion ................................................................................................................................................. 40 6 Appendices ................................................................................................................................................ 41

4 Annex 1: Monitoring of BIS Airborne Collision 2020 actions

Objective:

• to monitor whether programmed actions are delivered as planned in EPAS Vol.II (process monitoring);

• to monitor whether programmed actions have mitigated the safety issue (output monitoring).

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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N Action title Type of action

Status (process) Status (output) Notes

1 EASA with support of technical partners should demonstrat e feasibility of achieving interoperabi lity of different ¡Conspicuity devices/syst ems through ground communicat ion network while respecting data privacy requiremen ts

RES.0031

(existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

The task was launched in January 2023 and completed in June 2024.

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

https://www.easa.europa.eu/en/res earch-projects/i-conspicuity- interoperability-electronic- conspicuity-systems-general-aviation

Task delayed by 2 years compared to the original plan due to lack of funding and the COVID-19 pandemic.

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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N Action title Type of action

Status (process) Status (output) Notes

2 EASA should analyse ‘Net Safety Benefit’ and ‘Operational Safety Assessment’ concepts for use of ¡Conspicuity devices/syst ems in Flight Information Service

RES.0032 (existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

Ongoing

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

tb c

tb c

tbc

Build on RES.0031 results (dependency). Ongoing, the deliverables expected in Q1 2026 (instead of Q3 2024).

The expected deliverables are:

- List of ATM use cases and identification of related information elements

- List of regulatory areas requiring further development/clarification.

Started 6 months later due to lack of resources, no negative impact expected. Outcomes of the task might trigger additional activity.

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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N Action title Type of action

Status (process) Status (output) Notes

3 EASA should facilitate installation and promote use of ¡Conspicuity devices in all relevant aircraft at user affordable cost

SPT.0119

(existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

Completed but to be extended (see the comment)

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

CS-STAN Issue 4 - CS-SC002d — Installation of Mode S

elementary surveillance equipment - CS-SC004b — Installation of antennas - CS-SC005b — Installation of an ADS-B OUT

system combined with a transponder system - CS-SC031c — Exchange of conventional anti-

collision lights, position lights, and landing and taxi lights for LED-type lights

- CS-SC032c — Installation of anti-collision lights

- CS-SC036b — Installation of visual awareness lights

- CS-SC051d — Installation of ‘FLARM’ equipment

- CS-SC057a — Installation of an electronic conspicuity (EC) function

- CS-CS058a — Installation of traffic awareness beacon system (TABS) equipment

The action to be extended to cover period 2026- 2028 to support update ¡Conspicuity Roadmap endorsed by ESC.

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N Action title Type of action

Status (process) Status (output) Notes

4 EASA should actively support initiatives enhancing interoperabi lity of ¡Conspicuity devices/syst ems

Same as #3 Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

Same as #3

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

- ¡Conspicuity website - Sunny Swift: TURN IT ON - Sunny Swift: See and Avoid - Sunny Swift: Collision avoidance

- make yourself seen - Sunny Swift: ADS-L: see and be

seen - Examples of ¡Conspicuity devices - SERA.13001 Operation of an SSR

transponder - CS-STAN Installation of avionics - Sunny Swift issue 5: Turn it on - GA Community: iConspicuity

Same as #3

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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N Action title Type of action

Status (process) Status (output) Notes

5 EASA should promote good practices in airspace design that reduce ‘airspace complexity’ and ‘traffic congestion’ with aim to reduce risk of collisions involving uncontrolle d traffic

SPT.0120

(existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

Completed but to be extended (see the comment)

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

- Sunny Swift: Clearance to enter controlled airspace

- Sunny Swift: Airspace Complexity - Part 1

- Sunny Swift: Airspace Complexity - Part 2

- Sunny Swift: Be aware of TMZ +

The action to be extended to cover period 2026- 2028 so that potential outputs that could be implemented as a result of RES.0032 (e.g. ¡Conspicuity in RMZ/TMZ) could be promoted through this task.

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Best Intervention Strategy “Airborne Collision Risk” – Update 2025

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N Action title Type of action

Status (process) Status (output) Notes

6 Member States should consider ‘airspace complexity’ and ‘traffic congestion' as safety relevant factors in airspace changes affecting uncontrolle d traffic, including the changes along internationa l borders

MST.0038 (existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

Partially completed but to be extended (see the comment)

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

1) The feedback from standardization activities on MST.0038 - Indirectly yes, but not as specific MST action, this is done via EU Survey on MST actions. Looked at this from the perspective of 373 requirements on airspace structure.

2) The feedback collected through SM TeB from the MS on MST.0038 - An informative session was given to the SM TeB but no input was collected.

The action completed only partially (see status field). It is proposed to be extended to cover period 2026- 2028 so that potential outputs of RES.0032 could be implemented by the States (e.g. ¡Conspicuity in RMZ/TMZ).

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N Action title Type of action

Status (process) Status (output) Notes

7 EASA should ensure technical and operational compatibilit y of U-space and ¡Conspicuity solutions

RMT.0230

(existing)

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

The initial solutions for compliance with SERA.6005(c) are published and applicable. The ADS-L 4 MOBILE technical specification is still under development. The AMC and GM material shall be reviewed taking into account the results of RES.0031 and technological developments.

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

https://www.easa.europa.eu/en/doc ument-library/easy-access- rules/online-publications/easy- access-rules-standardised- european?page=14#_DxCrossRefBm 1523704446

See the justification.

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N Action title Type of action

Status (process) Status (output) Notes

8 EASA should conduct Safety Issue Assessment (SIA) of airspace infringemen ts

Internal SRM task

Delivered as planned? (tick the box below)

Ye s

N o

Partial ly

X

Justification:

SIA Airspace Infringement completed in December 2023.

New actions to update BIS? (tick the box below)

Ye s

N o

Partial ly

X

BIS SIA Airspace Infringement v1.1.doc

The recommenda tions from the SIA to be incorporated in the existing BIS Airborne collision risk either by updating the existing actions or their timeline.

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N Action title Type of action

Status (process) Status (output) Notes

9 EASA to explore the use of ¡Conspicuity data for enhanced safety monitoring of Airborne Collision Risk

Internal SRM task

Delivered as planned? (tick the box below)

Ye s

N o

Partia lly

X

Justification:

Initial discussions with D4S programme manager ongoing. The incorporation of ¡Conspicuity into the programme is expected in 2026+ along the integration of GA.

New actions to update BIS? (tick the box below)

Ye s

N o

Partia lly

X

D4S - Follow-up Session SAFESKY v202

5 Annex 2: EASA/EUROCONTROL roadmap

¡Conspicuity - a high level concept [Version: 2024-02-14]

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Problem description

Since 2010, there have been 69 fatal mid-air collisions resulting in 129 fatalities in EASA States. All of these accidents involved small aircraft not subject to air traffic control. The analysis of these accidents revealed that the primary concern was the pilots' lack of situational awareness of the surrounding traffic. Many of these collisions could have been avoided if the aircraft involved had been equipped with interoperable traffic situational awareness systems.

In parallel, the U-space regulations, via SERA.6005(c), requires all manned aircraft not subject to air traffic control to be continuously electronically conspicuous to U-space service providers (e-conspicuity). According to AMC1 SERA.6005(c) this could be achieved by transmitting aircraft’s position using ADS-B out on 1090 MHz or (if coordinated and implemented for this purpose in whole Europe) 978 MHz3F

4 or by transmitting information, in line with the ADS-L technical specification, using SRD860 frequency band or (if coordinated and implemented for this purpose in whole Europe) aerial mobile telecommunications services.

The new SERA.6005(c) requirement provided an opportunity to try to improve the interoperability of systems used by recreational pilots to provide situational awareness of surrounding traffic.

The objective should be a simple architecture ensuring interoperability and affordability with sufficient performance. Following finalization, the strategy needs to be clearly communicated, supporting pilots’ equipage decisions as well as USSP and other stakeholder's decisions.

Current situation

Several types of systems exist to improve pilots’ situational awareness and tens of thousands of these devices are currently in use. However, these systems are not always interoperable.

The main system is ADS-B (in Europe 1090 and in the US 1090 and UAT). There are several other systems transmitting position information in various open or proprietary formats operating on unlicensed but regulated and standardised spectrum (SRD860) or operating on telecommunication networks.

ADS-B 1090 and UAT systems are certified by EASA (ETSO), but systems operating on SRD860 and mobile telecommunication are not. The two latter, when commercially produced, are subject to EU market product regulation (CE marking). The systems on SRD860 use different languages which are not interoperable.

The diverse use of different technological solutions has resulted in a lack of interoperability in terms of communication protocol (language) and means of communication (link).

4 UAT - Universal Access Transceiver

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Scope (Use Cases) and objectives

The main objectives of the ¡Conspicuity concept are to:

• Reduce the risk of mid-air collisions by enhancing the pilot's situational awareness to assist in avoidance of collision and/or mitigation of other airborne hazards. It is not intended to serve as a collision avoidance system (i.e., ACAS), nor as a surveillance tool in support of Air Traffic Control (ATC), and,

• Enable electronic conspicuity for manned aircraft in U-space when not provided with air traffic control service. Electronic conspicuity in U-space is only required to operate air to ground and where U-space is established, which is expected to be in environments with higher levels of air-traffic (manned and/or UAS).

Possible additional objectives (subject to further research):

• Complement the Flight Information Service (FIS) and Search and Rescue without requiring changes to existing ATM/ANS principles and/or operational practices.

Target Situation

To ensure interoperability and affordability, a simple system design should be used. For the pilot awareness use case, the solution should be independent of any ground networks. While the electronic conspicuity in U- space will use ground networks.

No mandatory equipage is foreseen outside of U-space airspace. Implementation elsewhere is foreseen to be on a voluntary basis.

The objective is to apply the principle of ‘one language’ and ‘one link’.

 One language

A common ‘language’ is needed to ensure interoperability.

ADS-B and ADS-L are considered as good candidates for a common interoperable language(s).

 One link

A direct air-to-air radio link will be required and should be defined for the target situation.

The choice of the link(s) should be based on a comparative assessment of options, taking into account their respective operational acceptability, technical feasibility and business case for ground-based stakeholders and airspace users to meet the Use case requirements.

 Complementary link

It is recognized that in addition to (i.e. not instead of) the ‘one link’, ‘one language’, pilots may use other complementary solutions to enable enhanced functions and/or to display aircraft operating beyond radio line-of-sight.

The complementary link can provide more benefits by allowing additional applications outside the conspicuity solution. It can provide near real-time information to mitigate other airborne hazards such as weather, airspace or other (e.g., glider winch launch, ongoing aerobatics, model flying, etc.). It can also support the exchange of traffic information for situational awareness beyond the direct radio line-of-sight.

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Enabler Technologies

The proposed enabler technologies are based on existing technologies 1090 ADS-B, UAT, SRD860 and mobile telecom. The main characteristics of these technologies are provided hereafter:

 1090 ADS-B o The ADS-B 1090 systems are in operational use for ATS purposes for many years worldwide.

In Europe the ATS ground network is designed based on 1090 ADS-B. It uses a protected aeronautical spectrum and therefore requires formal approval (e.g. airworthiness certification) as well as radio licensing criteria to transmit, which risks making equipment less affordable for the end user. The 1090 MHz link sustainability should be assessed regarding equipage of low-end aircraft. A properly updated ADS-L could converge with a simplified 1090 ADS-B (e.g. low-power) for low-end aircraft.

 UAT ADS-B o The ADS-B UAT systems are in operational use for ATS purposes in the USA. It uses a

protected aeronautical spectrum and therefore requires formal approval, as such the same constraints as for 1090 applies regarding radio licensing, criteria to transmit, and affordability for the end user. The use of UAT in Europe will require frequency planning. UAT can enable other applications requested by the GA community such as FIS-B. A properly updated ADS-L could converge with UAT ADS-B for low-end aircraft.

 SRD860 o SRD860 systems use unprotected, unlicensed but regulated and standardised spectrum.

Currently it includes several non-harmonized systems, which would need to be upgraded to be interoperable with other SRD860 systems. It is noted that the SRD860 frequency allocation is at risk from ITU International Mobile Telecommunications (IMT) after 7-10 years (i.e. viable at least until 2030).

 Mobile telecommunication Existing mobile telecommunications services can already complement the ‘one link’ for operations at lower levels in much of the terrestrial parts of Europe4F

5. The mobile telecom does not enable direct air to air interoperability and requires a ground network in order to operate. The aeronautical use of such services will require a clear specification of communication requirements compatible with existing and future mobile telecommunications networks. The CEPT/ECC Decision (22)07 of 18 November 2007 on harmonised technical conditions for the use of aerial UE for communications based on LTE and 5G NR in the bands 703-733 MHz, 832-862 MHz, 880-915 MHz, 1710-1785 MHz, 1920-1980 MHz, 2500-2570 MHz and 2570-2620 MHz harmonised for MFCN provides the basis for such a specification. Current mobile networks could be further optimized to support this functionality, as has been done in Sweden, but the widespread use of Portable Electronic Devices (PEDs) by General Aviation pilots to view current weather and traffic data on apps has shown that it is also possible at low altitude with current networks.

5 EASA feasibility study concerning the suitability of use of mobile telecommunication technologies for making manned aircraft electronically conspicuous in U-space as required in the Commission Implementing Regulation 2021/666 of April 22, 2021.

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Approach

In order to address jointly the two uses cases described above, their different characteristics need to be considered in the assessment of possible solutions.

The conspicuity solutions should recognize that different aviation communities have different needs: The needs of a glider pilot are very different from the needs of the pilots and air traffic controllers of aircraft operating under IFR.

U-space requires all uncontrolled manned aircraft to be electronically conspicuous. It is currently envisaged that U-space airspace will only be introduced in areas of higher air traffic density (manned and/or unmanned), where the induced higher air risk needs to be mitigated. As such, conspicuity equipment will initially only be required in geographically limited low-level airspace.

On the other hand, pilot situational awareness is needed Europe-wide and equipage for this use case will be voluntary.

Furthermore, the conspicuity solutions overlap with existing solutions providing additional use cases, such as ADS-B enabling both ATC service and conspicuity.

It is important to ensure that aircraft are equipped with the appropriate solutions for the respective use case. To ensure this, the strategy needs to be clearly described and communicated, supporting stakeholder equipage decisions.

In order to define the solution, the following steps are envisaged:

1. Review and consolidation of use cases and related performance 2. ‘One language’ proposal by Q1 2025 (draft Q4 2024) considering the following:

a. ADS-L 4 SRD-860 Issue 2 and Draft ADS-L 4 MOBILE Issue 1 expected in Q2 2024 Information forward and uplink using SRD860 frequency band and aerial cellular Note: - RES.0031 research on ¡Conspicuity interoperability to be completed by Q2 2024 - RES.0032 research on ¡Conspicuity for FIS and SAR task to start in Q4 2024

b. Definition of ADS-L enabled on 1090 and UAT reduced capability equipment (RCE/Low power)

3. Comparative assessment of options (Use cases and requirements, Ops acceptability, Technical feasibility, Business Case incl. constraint mitigation for affordability) by 2025

4. Consolidation of ‘one link’ proposal by 2026 including transitional arrangements 5. Community awareness and endorsement of the concept to avoid proliferation of technologies in

the absence of a clear target and intermediate steps. 6. Implementation

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6 Annex 3: Safety Issue Assessment “Airspace Infringement”

Executive Summary of the SIA performed in 2022

Airspace infringements present a significant safety risk which has a negative impact on both IFR (instrument flight rules) and VFR (visual flight rules) flights and on the workload of Air traffic controllers.

The continuous increase of airspace infringements indicated that this is an pertinent safety issue.

European Central Repository (ECR) data shows that during 2016-2021 there were over 22,000 reported infringements in the geographic scope of Europe and North Atlantic. Many of these resulted in losses of separation with other aircraft. This continues a trend that has been ongoing for nearly twenty years.

Analysis of the data available from a number of different sources shows some clear trends. The majority of infringement events occur in terminal control areas (TMAs), controlled traffic regions, (CTRs) and control areas (CTAs) they involve general aviation (GA) pilots flying under VFR and occur due to navigation errors, poor pre-flight planning, airspace complexity, distraction in the cockpit, and/or difficulty dealing with unexpected or unfamiliar weather conditions.

The proposed actions are:

• Reduce airspace complexity • Training on airspace structure and navigation • Availability of up to date data • Airmanship • Reporting culture • Conspicuity • Pre-flight briefing facilities and tools

They are already included in the existing actions covered by the BIS Airborne Collision

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SIA Report – Table of content 1 Safety Issue Assessment ........................................................................................................................... 20

1.1 Introduction and purpose ............................................................................................................... 20 1.2 Definition of the Safety Issue .......................................................................................................... 20 1.3 Who is affected? ............................................................................................................................. 21 1.4 Assessment methodology ............................................................................................................... 21 1.5 Risk assessment approach............................................................................................................... 22 1.6 The total number of airspace infringements .................................................................................. 22 1.7 The Locations of Airspace Infringements ........................................................................................ 24 1.8 Airspace Users Infringing Controlled Airspace ................................................................................ 26 1.9 Causal Factors of the Infringements ............................................................................................... 28 1.10 Existing Actions................................................................................................................................ 30

1.10.1 ANSP Actions ...................................................................................................................... 30 1.10.2 Airspace Users (civil and military) Actions ......................................................................... 30 1.10.3 EPAS Actions ....................................................................................................................... 31

1.11 Results of the Safety Issue Assessment........................................................................................... 32 2 Baseline scenario-– What would happen if there is no additional action? .............................................. 34 3 Intervention objectives ............................................................................................................................. 34 4 List of proposed actions and assessment of their integration in the BIS Airborne Collision .................... 34

4.1 List of proposed actions and assessment ........................................................................................ 34 4.2 Detailed definition of proposed actions .......................................................................................... 39

5 Conclusion ................................................................................................................................................. 40 6 Appendices ................................................................................................................................................ 41

6.1 SIA Team composition ..................................................................................................................... 41 6.2 Occurrence Reporting Data ............................................................................................................. 41 6.3 Existing Bow Tie Models .................................................................................................................. 42 6.4 Documents Reviewed ...................................................................................................................... 42 6.5 European Action Plan for Airspace Infringement Risk Reduction ................................................... 42 6.6 EAPPAIR recommendations ............................................................................................................ 43 6.7 Historic data on contributional factors ........................................................................................... 60 6.8 UK CAA Bow-Tie Analysis ................................................................................................................ 63

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1 Safety Issue Assessment

1.1 Introduction and purpose

The EASA Safety Risk Management process aims at managing aviation safety risks, their conditions in an integrated manner, with the objectives of:

1. Prioritising safety actions which are most efficient in reducing risk levels 2. Ensuring adequate internal and external coordination on both key aspects of the Safety Risk

Management, which are: • The identification and assessment of safety issues, • Identifying existing mitigating actions, and • The programming of safety or mitigating actions

3. Providing transparency on why the Agency takes certain actions

In order to achieve these objectives, the Agency has established structured links between safety intelligence processes (safety analysis and performance) and safety action related processes (such as integrated programming, rulemaking, certification, organisations oversight, standardisation, safety promotion, corrective action in reaction to a safety problem/operational directives). These links foresee the need for an assessment of both the risks levels associated to certain safety issues, and the efficiency of the intended safety actions, in order to enable prioritisation of the safety issues. The scope is here limited to global or systemic safety issues that may affect European aviation products, services, or European passengers.

The Safety Risk Portfolio is the domain specific, common repository for recording and documenting the outputs of the above-mentioned tasks. Within the Safety Risk Portfolio for Air Traffic Management / Air Navigation Services (ATM/ANS), the safety issue “Airspace Infringement” has been raised and assessed to be of high priority by the CAG.

This paper documents the safety issue assessment carried out by the Assessment Team. It provides data and expert judgement, in addition to making specific recommendations regarding how best to manage this safety issue. This supports the governing bodies of the SRM process in their evaluation of the need for safety actions.

1.2 Definition of the Safety Issue

The term ‘airspace infringement’ refers to the unauthorised entry into controlled, prohibited, or restricted airspace, or an active Danger Area (where clearance to enter is required), by an aircraft. It occurs when aircraft fly into notified airspace without previously requesting and obtaining approval from the controlling authority of that airspace.

The four potential major consequences which may result from airspace infringements are:

Airborne collision: The worst-case scenario. Only the collaboration of all aviation actors can reduce the chance of this consequence to as low as practical (ALARP).

Loss of separation: An infringement leading to loss of prescribed standard separation (also known as Separation Minima Infringement) or close proximity of aircraft (where separation minima are not prescribed

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between aircraft) could have a number of consequences, e.g. loss of control due to wake vortex encounter, violent avoiding manoeuvres, and injuries to passengers or crew as a result.

Disruption to flight operations: Especially in congested airspace, there is potential for a significant increase in controller and pilot workload due to the need to break off an approach, change aircraft sequence for landing, or implement other contingency measures, as well as the resulting radiotelephony (R/T) congestion.

Adverse environmental and economic impact: This is a consequence of the disruption to flight operations, which can lead to delays. That in turn results in increased fuel burn by aircraft both in the air and on the ground. Such delays cause disruption to operating schedules and considerable inconvenience to passengers. While seemingly not directly safety-related, these factors increase the overall production pressures on the ATM (Air Traffic Management) system, thus indirectly creating potential safety risk.

1.3 Who is affected?

Affected are all airspace users, GA as well as CAT aeroplanes, civil as well as military airspace users and air traffic service providers.

1.4 Assessment methodology

This safety assessment was conducted by the Safety Issue Assessment (SIA) working group taking different sources of information into account:

• The expert judgement of the experts in the SIA team, • occurrence data and the European Action Plan for Airspace Infringement Reduction (EAPAIR) and • the data that were used for its production.

The scope of the assessment was as follows:

Criteria Scope

Time Period (Years) 2016-2021 for ECR data, qualitative data analysis based on data till 2021

Data Sources Primary: ECR

Other sources: Eurocontrol, literature review (see appendix 7.2(

Geographic Scope ECAC

Aircraft Information

CAT, GA powered, glider, hang- gliders, paragliders, Military Aircraft

Operation Type CAT, OAT, GA

Occurrence Class All

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Key Risk Area Airborne Collision

The SIA team(Appendix 6.19.1) analysed the data available in the European Central Repository (ECR). Occurrences were assessed with regard to the number of events that occurred, their locations and airspace classifications and the typical severity of the event outcomes.

A team of experts from CANSO Civil Air Navigation Service Organisation) ANSPs and Eurocontrol provided data and relevant analysis from across Europe. Over several months, the experts examined the available data from a number of ANSPs (collected via its Annual Safety Template), and conducted a literature review from these and other sources (Appendix 6.29.2) This examination sought to identify the common trends in:

• infringement location. • airspace classification. • flight rules under which the aircraft was operated. • event types.

The team then reviewed the actions taken by a number of ANSPs and studied the effect of these actions on safety performance before drawing conclusions for further action. Actions included in the EPAS dealing with airspace infringements were also reviewed.

1.5 Risk assessment approach

The assessment of this safety issue started in 2019 and was paused during the COVID pandemic as the SIA participants did undergo resource relocation during this time within their companies. The data was updated with the latest figures from the ECR in July 2022. Furthermore the SIA team referred to data on contributory factors from 2006 to 2011 ( Appendix 6.7 ) ere used and analysed by the ANSPs in working groups. The team reviewed all the available data to obtain a deeper understanding of the airspace infringements problem and to seek to identify trends.

1.6 The total number of airspace infringements

The query in ECR for airspace infringements in Europe and North Atlantic revealed 22003 occurrences for the year 2016-2021.

For Figure 1 only EASA MS were considered to be able to correlate the data with the exposure data (IFR flights in EASA MS). This query revealed 17617 occurrences for the years 2016-2021.

ECR data indicate that airspace infringement occurrences increased from around 1900 to almost 3700 until 2019 and dropped since then. However looking at the occurrence rate, airspace infringement occurrences plateaued till 2020, where they increased and decreased since then again.

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Figure 1 Airspace infringement rate in EASA MS, ECR 2017-2021

The following figures outline the number of airspace infringements from 2016- 2021 per month using the entire data sample of Europe and North Atlantic as state of occurrence.

Figure 2 Total number of airspace infringements, source: ECR,

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Figure 2 depicts the number of airspace infringement over the month of a year and it is visible that airspace infringement peak over the summer period.,

Analysing the occurrence class (Figure 3), 35% of the occurrences are rated as incidents followed by significant incidents (34%). 6 accidents with 2 fatalities occurred. It has to be clarified that the airspace infringement per se was not the cause of the accident with fatalities. It was an aerobatic aircraft that infringed controlled airspace and experienced during the aerobatic manoeuvre loss of control of the aircraft resulting in 2 fatalities. The other accidents involved ultra-light aircraft and paragliders. Occurrence class definitions are in line with ECCAIRS/ECR occurrence classes [Ref. ECCAIRS 2 Central Hub | Taxonomy Browser (aviationreporting.eu)].

Figure 3 Number of Airspace Infringement per occurrence class 2016-2021, source: ECR

1.7 The Locations of Airspace Infringements

Airspace Infringements can happen anywhere. However, they are most commonly reported in a limited number of location types. The most commonly infringed airspace structures are TMAs (terminal control area) and aerodrome CTRs (control zones) and CTAs (control areas).

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Figure 4 Location of Airspace Infringement 2016-2021, source ECR

The majority of infringements occur under circumstances where the infringing aircraft is in en route rather than departing or on approach.

Figure 5 Airspace infringement per flight phase 2016-2021- Source: ECR

7119 7003

3770

1104 1092 601 353 303 125 83 63 44 30 28 13 15 12 12 3 3 1

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1.8 Airspace Users Infringing Controlled Airspace

While all airspace users are clearly vulnerable to the risk of unintentionally infringing controlled airspace, reporting data shows that around 50% of Airspace Infringement events are reported as to involve aircraft flying under visual flight rules, while 17% are reported as being flown under instrument flight rules. It has to be mentioned that in the reporting system flight rules is not a mandatory field, therefore there are occurrences without any reference to the flight rules.

Figure 6 Airspace infringement per flight rule 2016-2021, source: ECR

Table 1 Airspace Infringement occurrences per type of operations and flight rule

Table 4 indicates that around 33% of the occurrences are reported as being non-commercial operations.

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In line with the flight rule data are also the data indicating the location of an airspace infringement in terms of airspace class. c)

Figure 7 Airspace infringement per airspace class source ECR, states: Europe and North Atlantic

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A B C D E G

Airspace Infringement per airspace class

Flight rule

Type of operations Controlled VFR

IFR Special VFR

VFR VFR Night

Unknown None/ Other

Grand Total

Non-Commercial Operations

20 464 12 6346 26 405 18 7158

Commercial Air Transport

0 2275 2 1156 8 453

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2 287 3 412 1 112 36 829

Specialised Operations (Aerial Work)

1 13 1 297 0 23 1 317

Others 0 0 3 1 10 8 22

Unknown 11 720 6 2272 3 575 27 3502

Grand Total 33 3699 24 11955 39 1500 90

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1.9 Causal Factors of the Infringements

For the following analysis the occurrences where IFR, VFR or both flight rules IFR and VFR in one occurrence were reported were considered. For simplicity and because of the minor numbers the specific categories night VFR, controlled VFR and special VFR flights were not considered.

All event types that were filed for more than 100 occurrences can be found in Figure 8. The top 3 event types for VFR flights are ATM Regulation Deviation, Personnel Attention and Vigilance Events and Flight Planning and Preparation.

Figure 8 event types for VFR flights if more than 100 occurrences were filed for one event type. Source ECR 2016-2021

Figure 9 depict the analyses of IFR flights and their associated reported event types.

All event types that were filed for more than 100 occurrences can be found in Figure 9.

The top 3 event types for IFR only flights are ATM Staff Clearance Deviations, ATM Regulation Deviation and Flight Crew ATM Procedure Deviation

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1000 1200 1400 1600 1800 2000

Event types for VFR flights

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Figure 9 Event types for IFR flights if more than 100 occurrences were filed for one event type; Source ECR 2016-2021

0 100 200 300 400 500 600 700 800 900

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Event types for IFR flights

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1.10 Existing Actions

As stated by the EAPAIRR Working Group, for an ATCO an airspace infringement is can be a startling, risky, difficult, and stressful events to deal with. It is explained by the fact that the ATCO often has limited ability to resolve the event because the infringing party is usually not in contact with the controller meaning that the flying intentions of the infringing party are unknown.

1.10.1 ANSP Actions

ANSPs have been in action for almost 20 years in order to tackle the risks associated with airspace infringements. Those involved in compiling this paper have taken many actions, including the following:

• Publication of a separate VFR guide (collections of parts of the AIP relevant for VFR) • Publication of conspicuity SSR codes • Introducing TMZs (100% success in reducing infringers in some areas) • Introduction of airspace Infringement Alerting Tools for ATCOs (e.g. Area Proximity Warning: APW) • Publication of mandatory or recommended transit corridors • Implementation of EAPPAIR actions in the (limited) field of ANSPs • Creation of GPS navigation ‘satnav’ mapping with controlled airspace alerts for GA pilots • Conducting GA flying (local VFR) clubs liaison visits – education & awareness presentations • Delivering education and awareness for training pilots, flying schools, aerial works companies,

federation representatives, etc. • Creating GA awareness websites • Holding annual meetings/ conferences with airspace users, e.g. GA flying associations • Establishing infringing pilot questionnaire programme • Publishing articles in widely-read VFR magazines • Changing lower boundary of TMA to altitude rather than 1000ft AGL • Including the above actions in ANSP safety plans

1.10.2 Airspace Users (civil and military) Actions

Also, airspace users have worked on their part to raise awareness and apply procedures where applicable. For an Airspace User it is suggested to:

• Contact Flight Information Services (FIS) when it’s available • Update regularly the database of the GPS system used as navigation support • Implement EAPPAIR actions in the field of Airspace Users (civil and military) • Improve the pre-flight preparation of pilots through briefing including aeronautical and

meteorological information • Use of refresher training to achieve and maintain an adequate level of navigation and

communications skills for GA pilots • Use of knowledge exchange programs between ATCOs, FISOs and Airspace Users • Enhance pilot proficiency checks beyond simple aircraft handling to include navigation and R/T

communication skills check carried out in the form of learning exercises

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• Improve pilot awareness of airspace infringement risk via safety promotion activities such as safety seminars, events, Internet fora, publications

• Improve the pre-flight preparation of pilots thru the capabilities of briefing facilities at the various GA locations

• Offer training courses to incentivise training for GA pilots • Encouraged pilots to be aware of their own training • Deliver additional training opportunities for “low-hours” pilots. • Designing of refresher training to achieve and maintain an adequate level of navigation and

communications skills • Implementing of knowledge exchange program

1.10.3 EPAS Actions

The latest version of EPAS 2022-2026 contains a group of actions addressing the risk of airspace infringement:

• MST.0024: ‘Due regard’ for the safety of civil traffic over high sea

• MST.0038: Airspace complexity and traffic congestion Member States should consider ‘airspace complexity’ and ‘traffic congestion' as safety-relevant factors in airspace changes affecting uncontrolled traffic, including the changes along international borders.

• RES.0021: SESAR 2020 research projects aiming to prevent mid-air collision risks (on hold)

• RES.0022: SESAR 2020 research projects aiming to safely integrate drones in the airspace The following research activities are being addressed under the SESAR 2020 programme: surface operations by UAS (PJ.03a-09); IFR UAS Integration (PJ. 10-05).

• RES.0023: SESAR exploratory projects on U-space SESAR JU has launched the U-space exploratory research as a step towards realising the EC U-space vision for ensuring safe and secure access to airspace for drones.

• RES.0031 Interoperability of different ¡Conspicuity devices/systems EASA, with the support of technical partners, should demonstrate and validate the feasibility of achieving interoperability of different ¡Conspicuity devices/systems through network of stations while respecting data privacy requirements.

• RMT.0727: Alignment of Part 21 with Regulation (EU) 2018/1139 (including simple and proportionate rules for General Aviation) Subtask 3: In a third phase, EASA will address all the other amendments required, including on the certification of non-installed equipment.

• RMT.0729, and RMT.0730: Regular update of Regulation 2019/947 and AMC/GM (drones in the open and specific category)

• RMT.0729: Dependencies to SI-2014 Integration of RPAS/drones

• RMT.0230 Introduction of a regulatory framework for the operation of drones Includes all the actions that are relevant to ensure the safe integration of UAS and eVTOL operated

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in the 'certified' and 'specific' (high-risk) category, including manned eVTOL aircraft operated in the 'certified' category into the aviation system.

• RMT.0690 Regular update of CS-STAN: The objective of this RMT is to regularly address miscellaneous issues of non-controversial nature, in order to ensure that the CS are fit for purpose, cost-effective, can be implemented in practice.

• RMT.0519 Regular update of CS-ACNS The objective of this RMT is to regularly address miscellaneous issues of non-controversial nature, in order to ensure that the CS are fit for purpose, cost-effective, can be implemented in practice, and are in line with the latest ICAO SARPs. In particular, a regular update is used to incorporate SCs, certification memoranda and other material supporting the application and interpretation of existing CS as established by EASA during previous certification projects, and to address non-complex and non-controversial issues raised by

• SPT.0091: European safety promotion on civil drones Coordinate European activities to promote safe operation of drones to the general public.

• SPT.120: Promoting Good Practises in Airspace Design Promote good practices in airspace design that reduce ‘airspace complexity’ and ‘traffic congestion’ with the aim of reducing the risk of airborne collisions involving uncontrolled traffic.

• SPT.0119: Promoting ¡Conspicuity

Facilitate installation of ¡Conspicuity devices in all aircraft holding an EASA TC and promote their use by airspace users at an affordable cost for them.

Support initiatives enhancing interoperability of ¡Conspicuity devices/systems

Note:

• RES.0032 was not initiated at the time of the SIA, therefore not considered in the SIA. The result of this task expected to be completed in 2026 will drive further the recommendations from the SIA.

1.11 Results of the Safety Issue Assessment

The continuous increase of airspace infringements indicated that this is an pertinent safety issue.

European Central Repository (ECR) data shows that during 2016-2021 there were over 22,000 reported infringements in the geographic scope of Europe and North Atlantic. Many of these resulted in losses of separation with other aircraft. This continues a trend that has been ongoing for nearly twenty years.

Analysis of the data available from a number of different sources shows some clear trends. The majority of infringement events occur in terminal control areas (TMAs), controlled traffic regions, (CTRs) and control areas (CTAs) they involve general aviation (GA) pilots flying under VFR and occur due to navigation errors,

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poor pre-flight planning, airspace complexity, distraction in the cockpit, and/or difficulty dealing with unexpected or unfamiliar weather conditions.

The proposed actions are:

• Reduce airspace complexity • Training on airspace structure and navigation • Availability of up to date data • Airmanship • Reporting culture • Conspicuity • Pre-flight briefing facilities and tools

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2 Baseline scenario-– What would happen if there is no additional action?

Figure 10 Airspace infringement and occurrence rate per million flights

Figure 10 indicates that airspace infringements have in increased with time and therefore. Without mitigation measures, the safety risks will remain.

The data and analysis presented in this paper demonstrate the airspace infringements poses still a risk to airspace users. Given the limited control that ATCOs and other pilots have over each situation, there is an increased risk of airborne collision caused by airspace infringements.

There is an increasing incidence of airspace infringement by unmanned aerial vehicles (UAVs), commonly referred to as drones. However, the risk posed by drones infringing CAS is, as yet, not clearly quantifiable and is, therefore, considered outside the scope of this SIA.

3 Intervention objectives

The objective of this safety issue assessment is to formulate actions than can prevent airspace infirngments and with that mid-air collisions.

4 List of proposed actions and assessment of their integration in the BIS Airborne Collision

4.1 List of proposed actions and assessment

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SIA “Airspace Infringement” recommendations for actions BIS/IA assessment

Action number

Action title Issue Objective Action type (RMT, SPT, RES, MST)

Scenario number

1 Reduce airspace complexity

Airspace complexity is a contributing factor to airspace infringments.

To reduce the risk of airspace infringements caused by airspace complexity in European Airspace and to avoid segregation of airspace for exclusive or restricted use as much as possible. EASA to support the MST and to review the EAPAIRR actions (see appendix 6.6), facilitating their incorporation into EPAS and/or SSPs, where appropriate.

MST

na This is already covered in MST.0038 and SPT.0120, which are extended to 2026-2028.

2 Training on airspace structure and navigation

Pilot navigation skills appear to play a role in airspace infringments.

To improve pilot training on airspace structure, navigation and use of navigation aids e.g. GPS

SPT, MST Pre-flight planning, Training

Navigation is one of the key skills tranined during initial training of pilots and is regularly checked.

GNSS spoofing and jamming to be considered.

Design of airspace along topographical features is considered in MST.0038

SPT.120 covers airspace complexity part. Therefore, the recommendation “Training on

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SIA “Airspace Infringement” recommendations for actions BIS/IA assessment

Action number

Action title Issue Objective Action type (RMT, SPT, RES, MST)

Scenario number

airspace structure and navigation “ does not need to be reflected as a separate action.

3 Availability of up to date data

If pilots have incorrect and unprecise data available for their flight planning the risk of an airspace infringement increases

To promote via GA roadmap that GA pilots have up to date information available

EASA, States, ANSPs and private flying associations to facilitate public access to airspace information in commonly used digital formats that are typically used by pilots

SPT

Pre-flight planning, Flight planning sources

This is already covered by SPT.0119 and SPT.0120.

4 Airmanship If transponders are not used correctly or pilots are not aware of the airspace they are flying in it increases the airspace infringement risks.

Continue safety promotion campaigns regarding the use of transponder , flight at proximity of controlled airspace, distraction)

EASA, states, ANSPs, and private flying associations continue to raise awareness among flying schools, instructors, clubs, and

SPT,MST

Escalating factor in UK bow tie (Appendix 6.8)

This is already covered by MST.0038, SPT.0119 and SPT.0120.

No MST need.

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SIA “Airspace Infringement” recommendations for actions BIS/IA assessment

Action number

Action title Issue Objective Action type (RMT, SPT, RES, MST)

Scenario number

individual pilots of the impact of airmanship on the ATM system.

5 Reporting culture

Reporting of airspace infringement should not lead immidiatly to a penalty.

Improve reporting culture and recognise just culture for GA pilots

MST

na MST.0027 is already in place (continuous). ¡Conspicuity Declaration was published in 2025.

6 Conspicuity If aircraft are not visible for all involved actors the risk of airspace infringement increases.

To improve conspicuity across the European region.

SPT

(RES.0031,RES .0032, SPT.0119)

na SPT.0119 Extension to 2026-2028

7 Pre-flight briefing facilities and tools

If the planning of the flight is not facilitated appropriately and therefore not carried out properly the risk

To facilitate access to pre-flight briefing facilities and tools.

SPT,MST

Pre-flight planning, Flight planning sources

This is already covered by MST.0038, and SPT.0120.

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SIA “Airspace Infringement” recommendations for actions BIS/IA assessment

Action number

Action title Issue Objective Action type (RMT, SPT, RES, MST)

Scenario number

of airspace infringement increases.

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4.2 Detailed definition of proposed actions

Action 1 Airspace complexity:

Complex airspace with multiple CTAs or differing levels and complex shapes are inherent airspace infringement hot spots. For example the numerous boundary level changes of TMAs and CTRs that can contribute to vertical navigation error.

The design should consider adjacent controlled airspaces to avoid creating narrow corridors that increase funnelling and risk of airspace infringement and airborne collision.

The action proposes for states to perform an assessment of the impact of airspace complexity on the workload for all affected airspace users and publish the results of an agreed objective measurement either for each airspace change or at regular intervals. Further more it proposes EASA to support the MST and to review the EAPAIRR actions (see appendix 6.6), facilitating their incorporation into EPAS and/or SSPs, where appropriate. Action 2 Training on airspace structure and navigation

Pilot navigation skills and appear to play a role in airspace infringments. Therefore continuous skill development and pilot training on airspace structure, navigation and use of navigation aids e.g. GPS shall be ensured.

EASA, States, and private flying associations to act to create a framework for assisting flying schools, instructors, clubs, and individual pilots to actively seek to maintain and/or increase pilot competence through continuous skills development. (see appendix 6.6)

Action 3 Availability of up to date data

Pilots can only use the navigation aids appropriately if they have up to date information at their hand. Therefore EASA, States, ANSPs and private flying associations 39ecogn facilitate public access to airspace information in commonly used digital formats that are typically used by pilots. This should be promoted via the GA roadmap.

Action 4 Airmanship

In the UK bow (Appendix 6.8) tie for airborne conflict in class A airspace with the threat “Unauthorisised penetration of UK class airspace by sport/ recreation or military flight the lack of secondary radar conspicuity due to non transponding traffic” is an escalating factor.

It is proposed to continue safety promotion campaigns regarding the use of transponder and flight at proximity of controlled airspace.

The action proposes for EASA, states, ANSPs, and private flying associations continue to raise awareness among flying schools, instructors, clubs, and individual pilots of the impact of airmanship on the ATM system.

Action 5 Reporting culture

Improve reporting culture and 39ecognize just culture for GA pilots. The action proposed for authority to consider just culture when GA pilots report a self-made error.

Action 6 Conspicuity

To improve conspicuity across the European region. The UK CAA’s bow tie analysis of the risk posed by airspace infringement (Appendix 6.8) identifies two major threats which are present: aircraft conspicuity and crew proficiency. The CAA’s analysis identifies a number of conspicuity issues, such as aircraft types with poor

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radar cross-section and a lack of SSR and ACAS conspicuity due to non-transponding aircraft, which is a violation of the rules of the air.

The action proposed for EASA and states to accelerate and promote equipage of ADS-B technology or alternative electronic conspicuity devices to broadcast information to ground, where ANSPs should use this information for surveillance purposes.

Action 7 Pre-flight planning facilties and tools

This action goes hand in hand with action 3. It proposed for EASA, states, schools, and clubs to support the way briefing is carried out and to identify appropriate facilities and tools to improve flight preparation effectiveness. This should facilitate access to pre-flight briefing facilities and tools. (see appendix 6.6)

5 Conclusion

The proposed SIA recommendations were reviewed. As a result, no new actions are necessary, all proposals are in the scope of existing actions reflected in the BIS Airborne Collision.

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6 Appendices

6.1 SIA Team composition

The assessment team was drawn from 7 organisations and comprised 7 contributors. The areas of expertise covered by the team were:

Role Organisation

Senior Expert Safety Intelligence DFS

Senior Safety Performance Expert ATC DSNA

Head of Operational and Consulting Services Dept. (former Safety Post Holder)

ENAV

Safety Manager IAA

Principal Safety Specialist NATS (UK)

Safety and Security Manager PANSA

Strategy Development Officer EASA

Table 2: Assessment Team Composition

6.2 Occurrence Reporting Data

i. European Central Repository (ECR) database. The European Coordination Centre for Accident and Incident Reporting Systems (ECCAIRS) provides the European Central Repository (ECR) for accident and incident reports in aviation.

ii. EUROCONTROL Airspace Infringement Initiative FIS Survey and Analysis parts 1-3. EUROCONTROL, 2008. Surveys and analysis of Airspace Infringement data within Europe, covering the time period of 2002-2008

iii. FABEC Airspace Infringement Analysis. Data analysis of Airspace Infringements within the FABEC area of responsibility of (ANA Lux, Belgocontrol, DFS, DSNA, LVNL, MUAC, Skyguide), covering the time period of 2013-2016.

iv. NATS (UK) Airspace Infringement Analysis Data analysis of Airspace Infringement reports in UK airspace, covering the time period of 2012-2015.

v. IAA Airspace Infringements Analysis Data analysis of Airspace Infringement reports in Irish airspace, covering the time period of 2012-2016.

vi. ENAV Airspace Infringements ENAV case study of Airspace Infringements within the Milano CTA-TMA, covering the time period of 2013-2016.

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6.3 Existing Bow Tie Models

• UK CAA Bow-tie analysis of Airspace Infringement Risk, 2012 (Appendix 6.8A) • SESAR AIM Mid-Air Collision Risk Model (en route and TMA operations), 2016 (Appendix B)

6.4 Documents Reviewed

• European Plan for Aviation Safety (EPAS) 2022-2026 EASA, 2022

• Safety Issue Assessment: Deconfliction with IFR/VFR traffic EASA, 20189 Note: this SIA was then integrated in the BIS Airborne Collision consultated with the Advisory Bodies in 2020

• European Action Plan for Airspace Infringement Risk Reduction (EAPAIRR), Version 2.0, EUROCONTROL, CANSO, 2022 https://www.eurocontrol.int/sites/default/files/2022-03/eurocontrol-airspace- infringement-action-plan-v2-0.pdf

• PRB Monitoring Report. Safety Volume, years 2015, 2016, 2017 Performance Review Body of the Single European Sky, European Union

• Airspace Infringement: Guidance for GA Pilots EUROCONTROL, 2009

• Communication Guide for General Aviation VFR Flights EUROCONTROL, 2009 https://www.easa.europa.eu/en/document-library/general- publications/egast-radiotelephony-guide-vfr-pilots

• Top Ten Tips for GA Pilots Eurocontrol, 2010 https://skybrary.aero/airspace-infringement-poster-top-ten-tips-ga-pilots

• Airspace Infringement Prevention Toolkit EUROCONTROL, based on a collection of best practises from all over Europe. https://skybrary.aero/tutorials/airspace-infringement-prevention-toolkit

• Decision Making for General Aviation Pilots EASA, European General Aviation Safety Team (EGAST), 2011 https://www.easa.europa.eu/sites/default/files/dfu/EGAST_Brochure_Decision- making_low_110404.pdf General Aviation Safety Sense Leaflets from UK CAA, 2003-2016

• CAP1535 – The Skyway Code UK CAA, 2021 https://publicapps.caa.co.uk/docs/33/CAP1404%20Edition%205%20(August%202021).pdf

• Avoiding Airspace Infringements Videos Campaign by:

EASA, UK CAA, Finnish CAA, Belgian CAA, Swiss CAA, Norwegian CAA https://www.easa.europa.eu/airspace-infringement

6.5 European Action Plan for Airspace Infringement Risk Reduction

In 2019 EUROCONTROL and CANSO jointly undertook a round of stakeholder engagement with ANSPs, national authorities, and European General Aviation associations. The stakeholder engagement resulted in the formation of a EAPAIRR Working Group consisting of representatives from a number of ANSPs, state

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regulators, and General Aviation representatives as well as EASA representation. The Working Group met for the first time in September 2019 and continued to meet throughout the COVID-19 pandemic. They realised its aim of publishing a renewed EAPAIRR V2.0 in April 2022. The purpose of the new EAPAIRR is to reduce risk and support airspace users, civil and military service providers, and national authorities in implementing the recommended safety improvement measures for the timeframe 2022-2030. EAPAIRR contains recommendations and best practice examples which can be partly or wholly incorporated in the EPAS and/or the SSPs.

6.6 EAPPAIR recommendations

European Airspace Infringement Action Plan | SKYbrary Aviation Safety

EAPAIRR v2.0 Recommendations (European Action plan for Airspace Infringement Risk Reduction, EAPAIRR version 2.0; CANSO, Eurocontrol, March 2022)

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6.7 Historic data on contributional factors

Individual ANSPs, the States, Eurocontrol, and EASA all hold a variety of data sets derived from their reporting systems, but also from other initiatives such as questionnaires which have been returned by those infringing pilots who have been identified. These data sources give the possibility to further analyse the data in a qualitative way. The following figures depict data from 2006-2011 as an analysis considering this timeframe was executed by the safety partners. Even if the data are “historic” data their validity is still assumed.

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Figure 11 Airspace Infringements – Causal Factors, 2006-2011 - Source: Eurocontrol

The main causal facture for airspace infringement revealed in the data review was navigation failure, followed by non-adherence to procedures, inadequate communication and inadequate aircraft control. These data broken down further revealed that the navigation failure is impacted by the inadequate knowledge of the airspace structure and procedures as can be seen in Figure 10.

Figure 12 Airspace Infringements – Causal Factors (for Navigation Failure), 2006-2011 - Source: Eurocontrol

The complexity of airspace is cited by GA pilots particularly, as a major problem which can cause a loss of or recurring gaps in situational awareness, and even loss of orientation. Complex airspace can contribute to misidentification of ground features. EUROCONTROL’s Airspace Infringement Risk Analysis (2007) revealed a strong consensus of opinion among pilots that the considerable number of restricted zones and areas

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(including temporary segregated areas) and their dynamic management (activation/deactivation by NOTAMs) cannot easily be followed by GA. It may also result in pilots deciding to take shortcuts.

The UK CAA’s bow tie analysis of the risk posed by airspace infringement (Appendix A) identifies two major threats which are present: aircraft conspicuity and crew proficiency. The CAA’s analysis identifies a number of conspicuity issues, such as aircraft types with poor radar cross-section and a lack of SSR and ACAS conspicuity due to non-transponding aircraft, which in CAS is a violation of the rules of the air. Crew proficiency includes airmanship and the knowledge and/or ability to properly use navigation and transponder equipment.

Further follow-up action and analysis by the ANSPs involved in this study (Eurocontrol, 2007) show more detail behind the headline causes. Investigation and questionnaires across a number of the states involved provide the following granularity:

• Poor/inadequate pre-flight planning occurred • Pilots were unaware of airspace classification • Airspace complexity was contributory • Limited use of technology during pilot training was a factor • Limited availability of technology in cockpit of GA aircraft was a factor • Limited use (or non-availability) of transponders had a role • Diminishing skills of “low-hours” pilots was significant • Pilots not being aware of crossing vertical boundary of airspace. • Pilots were climbing according to FPL without clearance from ATC • Lack of experience/confidence when encountering bad weather contributed • Mis-identification of terrain features was a factor • Pilot distraction/complacency was present • Lack of pilot refresher training (for non-CAT pilots) aggravated the situation • Lack of commonality in procedures for GA pilots flying across multiple European airspace

boundaries is a factor • Reluctance or fear of contacting air traffic controllers • Aeronautical Information timely acquisitions

The data from ANSPs and Eurocontrol supports the view that in the majority of cases involving GA pilots, the principal reasons for the infringement occurring were navigation errors and distraction in the cockpit whilst airborne. Weather, and the need to unexpectedly avoid it, also played a significant part in creating the chance for infringements to occur. Furthermore, although not identifiable within the data, the occasions where pilots fly within 500ft of the base of controlled airspace gives rise to an anomaly, whereby no Airspace Infringement has occurred; nor has there been any ‘loss of separation’; but separation minima have been infringed as a result of the positions of the aircraft inside/outside controlled airspace. It may be worth considering the extent to which this situation increases the likelihood of airspace infringement and whether it has a significant impact on controller workload.

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6.8 UK CAA Bow-Tie Analysis

Risk of mid-air collision due to Airspace Infringement

EPAS preparation – 10 December 2025 Best Intervention Strategy BIS15 “Aircrew Fatigue (SI-0039)”

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Note on bundling the Safety Issues related to fatigue: SI-3005 addresses fatigue across all aviation personnel other than flight and cabin crew. By contrast, SI-0039 focuses exclusively on flight and cabin crew within the FTL/FRM regulatory framework. The two SIs are complementary and intentionally form a total system approach: SI-0039 concentrates on aircrew specific rules and oversight, while SI-3005 targets cross domain culture, technology, scientific evidence and implementation support for non-crew roles. To avoid duplication of activities, this BIS report includes one action on the quality improvement of safety data related to non-aircrew staff.

Executive Summary

1. Why intervene?

This document updates the previous version of the Best Intervention Strategy (BIS) for Aircrew Fatigue (version year 2019). The BIS assumes that the responsibility to manage fatigue risks is shared principally between operators and crew members but also national competent authorities. This is an aspect that has shaped all regulatory interventions, and a crucial point mentioned during all safety promotion tasks.

The safety analysis (Appended to BIS) studied data collected in the European Central Repository of occurrences from 2019 to 2023. While there have been no aircrew fatigue related occurrences confirmed to be a serious incident or accident in CAT scheduled and charter aeroplane operations in this period, there was a significant increase for both absolute numbers and rates of reported fatigue related occurrences observed in 2023. The rate of reported fatigue related occurrences in 2023 is 21 per one million flights.

However, the analysis of the content of fatigue reports does not allow us to draw clear qualitative or quantitative conclusions.

2. Proposed actions in the Best Intervention Strategy “Aircrew Fatigue”

This Bis analyses a combination of new actions and actions from the previous BIS that are still relevant.

When performing the analysis, EASA relied primarily on information from its standardisation and oversight activities. However, it is recognised that a more accurate picture of the issues related to fatigue and FTL/FRM would only be possible when considering implementation and oversight information that is currently available only to the NCAs and operators.

The actions proposed in this BIS should be also addressed and coordinated through the Advisory Bodies (namely the Air Ops TeB and FTL/FRM Expert Groups).

The principles enshrined in the strategy can be summarised as follows –

• Ensure that FTL regulations and their effectiveness continues to be evaluated • Shared responsibility concept is re-enforced by all stakeholders • Strengthen the standardisation activities related to FTL/FRM oversight • Strengthen effectiveness of FTL/FRM oversight by the NCAs • Promote and improve quality level of fatigue reporting, including occurrences

The actions have remained fairly stable since the last version of the BIS (2019), however the expected deliverables of some of the actions have been updated to reflect new realities of the industry.

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# Action title Action type

Benefit* EASA resources 2025 2026 2027 2028

1 Event dedicated to FTL/FRM.

SPT.0116 Medium Mission budget: 1mission x 1000 euro x 5 experts = 5 000 euros

Conference - Q1

Conference – Q1

Conference - TBD

2

RMT.0492 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS) RMT.0493 Update and harmonisation of the FTL rules for CAT by aeroplanes for air taxi And single-pilot operations.

RMT. 0492

RMT.0493

High 2025-2027: 0,1 FTE/year

1. Opinion

2. EDD

1. Workshop with AB

3 Further actions following study of the effectiveness of FTL - Phase 2 of the research.

New Others

Medium EASA 0.2 FTE/year TBD

4 EASA Standardisation - focus on FTL/FRM during OPS standardisation inspections.

STD Medium Refer to STD budgets.

Ongoing

5 Provide better guidance on issues related to fatigue reporting

NEW SPT Medium 2026-2028: 0.1 FTE/year

Safety Promotion /

Guidance Documents

6 ECCAIRS Taxonomy Update

NEW Others

Medium 2026-2027: 0.2 FTE/year [More resources to be considered for the full review by the NoA, not limited to EASA resources]

Review by Network of

Aviation Safety

Analysts (NoA) and FTL/FRM

expert groups

Update of Taxonomy

[provisional timeline – subject to

overall taxonomy updating process]

7 Data collection and analysis related to handling of fatigue reports, and results of FTL/FRM oversight.

New MST Medium 2028: 0.2 FTE Survey to MS

Apart these aircrew actions, and as introduced in the top grey box above the Executive Summary, the annex B “SIA SI-3005 Fatigue in non-aircrew personnel” recommended to work on taxonomy refinements (linked to action 6 above) and clearer guidance for those coding fatigue occurrences for non-aircrew personnel. It is proposed to use the current Member States Tasks for these purposes:

o MST.0002 Promotion of SMS o MST.0043 Improvement of data quality in occurrence reporting

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BIS Report – Table of content 1 Issue analysis ............................................................................................................................................... 6

1.1 General description ........................................................................................................................... 6 1.1.1 Flight Time Limitations (FTL) regulations and their effectiveness ....................................... 6 1.1.2 Shared Responsibility ........................................................................................................... 6 1.1.3 Standardisation activities and oversight effectiveness ........................................................ 7 1.1.4 Results of the Safety Analysis ............................................................................................... 7

1.2 Who is affected? ............................................................................................................................... 9 1.3 Past and existing actions ................................................................................................................... 9

1.3.1 Past Actions .......................................................................................................................... 9 1.3.2 Existing Actions .................................................................................................................. 11

1.4 List of proposed actions .................................................................................................................. 12 1.4.1 Baseline scenario – What would happen if there were no additional actions? ................ 12 1.4.2 Objectives ........................................................................................................................... 12 1.4.3 List of proposed actions ..................................................................................................... 12

Assessment of the revised and new actions ................................................................................................... 13 1.5 ACTION #1. - Events dedicated to FRM (SPT.0116) ......................................................................... 13

1.5.1 What is the action? ............................................................................................................ 13 1.5.2 What will the action achieve? ............................................................................................ 14 1.5.3 What is the technical content of the action? ..................................................................... 14 1.5.4 Interfaces to be considered ............................................................................................... 14 1.5.5 How will the action be monitored? .................................................................................... 14

1.6 ACTION # 2: RMT.0492 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS) and RMT.0493 FTL rules for CAT by aeroplane for air taxi operations and single-pilot operations taking into account operational experience and recent scientific evidence ........................................................................................................................... 14 1.6.1 What is the action? ............................................................................................................ 14 1.6.2 What will the action achieve? ............................................................................................ 15 1.6.3 What is the technical content of the action? ..................................................................... 15 1.6.4 Impact analysis ................................................................................................................... 15 1.6.5 Time implementation ......................................................................................................... 15

1.7 ACTION # 3. Further actions following results of the research study of the effectiveness of FTL - Phase 2 (RES.0006). ......................................................................................................................... 15 1.7.1 What is the action? ............................................................................................................ 15 1.7.2 What will the action achieve? ............................................................................................ 17 1.7.3 Description of the activity on controlled rest .................................................................... 17 1.7.4 Time implementation ......................................................................................................... 17 1.7.5 Implementation cost .......................................................................................................... 17

1.8 ACTION # 4. Standardisation on FTL/FRM ....................................................................................... 17 1.8.1 What is the action? ............................................................................................................ 17 1.8.2 What will the action achieve? ............................................................................................ 18 1.8.3 What is the technical content of the action? ..................................................................... 18 1.8.4 Impact Analysis .................................................................................................................. 18 1.8.5 Time implementation ......................................................................................................... 18 1.8.6 Implementation cost .......................................................................................................... 18

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1.9 ACTION #5 Provide better guidance to crew, operators and NCA’s on issues related to fatigue reporting. (NEW - SPT-TBA) ............................................................................................................. 18 1.9.1 What is the action? ............................................................................................................ 18 1.9.2 What will the action achieve? ............................................................................................ 18 1.9.3 What is the technical content of the action? ..................................................................... 19 1.9.4 Impact Analysis .................................................................................................................. 19 1.9.5 Time Implementation ......................................................................................................... 19 1.9.6 Implementation cost .......................................................................................................... 19

1.10 ACTION #6 Update the ECCAIRS taxonomy for fatigue reporting – NEW – NOT AN EPAS ACTION19 1.10.1 What is the action? ............................................................................................................ 19 1.10.2 What will the action achieve? ............................................................................................ 19 1.10.3 What is the technical content of the action? ..................................................................... 20 1.10.4 Impact Analysis .................................................................................................................. 20 1.10.5 Time implementation ......................................................................................................... 20 1.10.6 Implementation cost .......................................................................................................... 20

1.11 ACTION #7 Data collection and analysis related to fatigue reports and FTL/FRM oversight. (NEW - MST.TBA) ......................................................................................................................................... 20 1.11.1 What is the action? ............................................................................................................ 20 1.11.2 What will the action achieve? ............................................................................................ 20 1.11.3 What is the technical content of the action? ..................................................................... 21 1.11.4 Impact Analysis .................................................................................................................. 21 1.11.5 Time Implementation ......................................................................................................... 21 1.11.6 Implementation cost .......................................................................................................... 21

1.12 Postponed or Discarded actions ..................................................................................................... 22 Analysis of impacts of proposed actions ................................................................................................... 23 1.13 Analysis of impacts .......................................................................................................................... 23

Best Intervention Strategy ............................................................................................................................... 24

APPENDIX A – SAFETY ANALYSIS REPORT ........................................................................................................ 26

1 Executive summary ................................................................................................................................... 31

2 Introduction .............................................................................................................................................. 32

3 The problem statement ............................................................................................................................ 33

4 Analysis ..................................................................................................................................................... 33 4.1 Setting the scene – macro view ...................................................................................................... 33

4.1.1 Fatigue related occurrences overview – all aviation domains and personnel ................... 33 4.1.2 Fatigue related occurrences involving CAT Aeroplanes, all aviation personnel ................ 34 4.1.3 Fatigue related CAT Rotorcraft occurrences ..................................................................... 35

4.2 Fatigue related CAT aircrew occurrences leading to operational events ....................................... 36 4.2.1 Event type analysis ............................................................................................................. 37 4.2.1.1 Consequential events analysis ........................................................................................... 40 4.2.2 Occurrence class ................................................................................................................ 41 4.2.3 Occurrence categories ....................................................................................................... 42 4.2.4 European risk classification scheme .................................................................................. 42 4.2.5 Per State of operator.......................................................................................................... 43 4.2.6 2023 occurrence with operational events – narrative review ........................................... 44

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4.3 Focus areas review .......................................................................................................................... 48 4.3.1 Commander’s discretion .................................................................................................... 48 4.3.2 Duty time extension ........................................................................................................... 50 4.3.3 Stand by duty ..................................................................................................................... 51 4.3.4 Rest time less than required .............................................................................................. 52 4.3.5 Tired ................................................................................................................................... 52 4.3.6 Acclimatisation ................................................................................................................... 53 4.3.7 Multiple sector ................................................................................................................... 54 4.3.8 Awake ................................................................................................................................. 55 4.3.9 Long night duty .................................................................................................................. 55 4.3.10 Controlled rest ................................................................................................................... 56

4.4 Conclusions after the occurrence narrative review. ....................................................................... 56 4.5 Proposed actions ............................................................................................................................. 57

4.5.1 To explore other data sources for aircrew fatigue assessment [STD, MST] ...................... 57 4.5.2 To provide guidance for operators and Member State authorities on fatigue related

occurrence processing and ERCS application [MST, SPT.0057] ......................................... 57 4.5.3 Remind and maintain the focus on fatigue, its prevention, and consequences [SPT.0116,

SPT.0117 and SPT.0118] ..................................................................................................... 58 4.5.4 To update the ECCAIRS taxonomy [NoA action] ................................................................ 58

5 Conclusions ............................................................................................................................................... 59

Attachment A: Acronyms and Definitions (Optional – if required) ................................................................. 62

APPENDIX B – SAFETY ISSUE ANALYSIS “SI-3005 Fatigue in non-aircrew personnel” ..................................... 63

1. Executive Summary ................................................................................................................................... 63

2 Safety Issue Assessment ........................................................................................................................... 65 2.1 Introduction and purpose ............................................................................................................... 65 2.2 Definition of the Safety Issue .......................................................................................................... 65 2.3 Who is affected? ............................................................................................................................. 66

2.3.1 Global analysis .................................................................................................................... 67 2.3.2 In-depth analysis ................................................................................................................ 67

2.4 Assessment methodology ............................................................................................................... 70 2.5 Risk assessment of the scenarios .................................................................................................... 71 2.6 Existing Actions................................................................................................................................ 72

3 Baseline scenario-– What would happen if there is no additional action? .............................................. 73

4 Intervention objectives ............................................................................................................................. 73

5 Proposed actions ....................................................................................................................................... 74 5.1 List of proposed actions .................................................................................................................. 74 5.2 Detailed definition of proposed actions .......................................................................................... 75

6 Conclusion ................................................................................................................................................. 77

SIA Appendix 1 ................................................................................................................................................. 78

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1 Issue analysis

1.1 General description

Addressing aircrew fatigue is crucial for ensuring the safety and well-being of flight personnel. Effective intervention strategies for managing aircrew fatigue involve a combination of regulatory, operational, organisational, and individual approaches.

Economic, social and regulatory factors all have a contributing role to the issue of aircrew fatigue. Aircrew fatigue may be a controversial subject due to the inherent challenges in balancing safety requirements with operational efficiency, the subjective nature of fatigue, social and economic considerations, and resistance to change within the industry. Finding common ground and implementing effective fatigue management strategies require ongoing collaboration and a nuanced understanding of the multifaceted nature of the issue.

The Safety Issue Assessment in Appendix A has been used for the issue analysis. This analysis of fatigue data was performed to identify safety risks to update the previous BIS version 2019. It is important that all stakeholders understand their responsibilities and consequences of reporting, including quality of reports which would directly impact an effective fatigue risk analysis.

1.1.1 Flight Time Limitations (FTL) regulations and their effectiveness Fatigue can negatively affect aircrew performance in the aircraft and pose a hazard to flight safety. In commercial air transport, aircrew rosters are traditionally developed based on prescriptive duty time limits, flight time limits, minimum rest requirements and other constraints, such as minimum notification times and prohibition to combine certain duties, to name a few. These limits and requirements, referred to as flight time limitations (FTL), are presumed to be adequate for maintaining aircrew fatigue at levels that will not put at risk the safety of flight operations.

Prescriptive limitations have been designed to discipline operators’ crew scheduling practices, but they often become ineffective on the day of operation. In day-to-day operations, where roster changes, long delays, maintenance problems, commercial pressure and circadian disruption are frequent occurrences, the effectiveness of prescriptive limits is in fact undermined. The risks arising from crew members’ fatigue in real operations can only be mitigated when the prescriptive FTL are being supported by an effective fatigue risk management process.

Two approaches are today referred to as best industry practices that may complement prescriptive FTL: an appropriate fatigue risk management (appropriate FRM) within the operator’s safety management system (SMS) and a robust fatigue risk management system (FRMS). Action#3 relates to this issue.

1.1.2 Shared Responsibility The prevention of fatigue is one of the key responsibilities of an operator’s executive management (e.g. Accountable Managers and nominated persons), its crew rostering and crew dispatch personnel, and, last but not least, the crew members themselves.

National competent authorities are also directly involved, as they are responsible for the approval and oversight of operator’s FTL schemes and management systems where fatigue risk management could be a key component.

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Therefore, the concept of shared responsibility underpins this BIS and will be re-enforced. Actions #1, 3 and 4 relate to this issue.

1.1.3 Standardisation activities and oversight effectiveness FTL/FRM topics are still part of the OPS standardisation visits in Member States. Around 20% of the total undertaking non-compliances (UNC) raised during standardisation visits in 2022 and 2023 are related to FTL/FRM topics. This shows that more action is needed to ensure a uniform implementation of the rules and to ensure that the competent authorities discharge their oversight obligations effectively.

The main non-compliances identified through standardisation are:

• Lack of operational robustness (ORO.FTL.110) of operators’ rosters;

• Fatigue risk management is not effectively implemented;

• Individual Flight time specification schemes (IFTSS) are not customised by the operator;

• Procedures for assignment of an FDP following standby preventing a more than 18 hours awake time are not correctly set up or implemented;

• Times related to pre-flight and post-flight duties do not reflect the type of operation;

• NCAs’ procedures for approval of IFTSS do not ensure that operators’ IFTSS are customised for the operation.

This shows that competent authority’s oversight and uniform implementation of the FTL/FRM rules, together with an assessment of the inspector’s competence, still requires attention and efforts. Action#4 is linked to this issue.

1.1.4 Results of the Safety Analysis

1.1.4.1 Fatigue Reporting0F

1 Fatigue may be difficult to predict or diagnose. In some cases, there could be wrong subjective self- assessment, most likely due to insufficient experience or inadequate training. Any management system, however, cannot be effective without sufficient objective and subjective data. This also applies to fatigue risk management. Aircrew fatigue reports are a substantial part of the subjective data gathering that feeds the operator’s fatigue risk management processes.

There are also other objective and subjective reasons why fatigue remains not adequately captured or unreported, such as poor safety culture in the operator’s organisation, fear of dismissal or demotion, etc.

1 Fatigue is a reportable occurrence under Regulation (EU) 2015/1018.

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1.1.4.2 Commander’s Discretion The safety analysis looked at occurrence reports with a particular focus on issues typically linked to fatigue. One of the most common issues reported by operators, crew representatives and national competent authorities is Commander’s Discretion (CMD). The Agency also receives a considerable amount of Confidential Safety Reports (CSRs) linked to this provision. As shown in the safety analysis (4.3.1), the use of commander’s discretion has increased in recent years. There is a need for competent authorities to review and operators to be aware of the adequate use of ‘commander’s discretion’ – so it is not already foreseen in the roster planning and scheduling but is really used for unforeseen circumstances.

1.1.4.3 States reporting occurrences Around 50% of all occurrences are stemming from operators of 4 states. This could imply that reporting culture as well as practices to integrate fatigue related occurrences within the ECR are widely differing among the EASA member states (some states are integrating all fatigue related occurrences, some partially, some not at all). The majority of all fatigue related occurrences in the analysis involved Spanish operators (26%) and Sweden (13%) followed by Belgium, Germany, and Switzerland that would cover more than half of all occurrences.

1.1.4.4 Other Areas The safety analysis, included a review of occurrences through keywords which could be associated with crew fatigue related to:

- acclimatisation, - duty time extension, - standby duty, - long night duty, - reduced rest period, - rest time less than required, - duty time, - Awake time, or - controlled rest.

1.1.4.5 Limitations of the analysis The analysis of the fatigue reports in the European Central Repository (ECR) shows that there is no homogenous approach for integration of the fatigue related occurrences in the repository by all competent authorities. Some Member States integrate all occurrences, some integrate parts, some do not integrate at all.

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Also, the information available in the occurrence records is lacking the required level of detail to allow an understanding of the outcomes of the investigation and analysis of those occurrences, which does not allow to validate whether present FTL and FRM provisions are sufficient to address this contributing safety issue.

Follow-up information is also not always available in the records. As indicated in the Safety Analysis, out of the 100% of occurrences analysed (311 events), due to data quality issues, the analysis is limited to 49% of the occurrences, while 39% are in an unclear state (unable to derive conclusions), which however could be related to fatigue issues.

All this limits the possibility to derive final conclusions on this topic and requires additional sources of information to be reviewed, such as outcomes of oversight activities in the area of FTL/FRM. Actions # 5,6 and 7 are linked with these issues.

1.2 Who is affected?

The actions proposed by this BIS will affect European operators and their flight and cabin crew members. The proposed actions will also affect activities and resources of MS’s competent authorities and EASA.

1.3 Past and existing actions

1.3.1 Past Actions Flexibility provisions and support material

To support the implementation of FTL requirements, EASA held multiple FTL workshops throughout the FTL rollout phase and provided on-site support to a number of MS. A webinar on fatigue risk management in Cargo and On-Demand operations was held on 15 March 2021. This interactive online workshop provided examples on implementation of FRM in cargo and on-demand operations. An exchange on the technological support of FRM was also provided. Other workshops on FRM for fixed wing operators were held in January 2024 in Vienna and in February 2025 in Madrid. These were co-hosted with AustroControl and AESA respectively, with participation of competent authorities, industry and social partners.

EASA also undertook initiatives aimed at providing implementation support to competent authorities in need and is available for further assistance. EASA developed FTL/FRM Inspector’s checklists1F

2, which were first published in 2019, complemented in December 2022, and updated in 2024. A collection of good practices in the implementation of FTL requirements was made available to competent authorities in Q1 2025. This has completed remaining actions under SPT.0118.

2 https://www.easa.europa.eu/en/domains/air-operations/air-operations-general

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In addition, EASA partnered with FTL/FRM experts from MS and industry to solve ad hoc implementation issues and respond to everyday queries from interested individuals or organisations. As a result of this partnership, EASA has updated its FAQs2F

3 and updated the tools for evaluation of operator’s IFTSS.

Ad-hoc support measures were provided to all MS during the Covid-19 pandemic breakdown. After assessing the initial impact of the outbreak on all types of operations, and consulting the Advisory Bodies, EASA published guidelines to support FTL-related flexibility provisions under Article 71(1) of the BR.

The Guidelines were intended to help operators identify mitigation measures while performing risk assessments, and support MS in granting exemptions in the context of the pandemic. These flexibility provisions were essential to allow continuity of operations during challenging periods where crew members were not allowed to make use of proper rest facilities. A total of 184 exemptions issued by MS under Article 71(1) of the BR were notified to EASA.

Regulatory Tasks

During the adoption of EU Flight Time Limitation (FTL) requirements for scheduled and charter airline operations, the European Parliament and the Commission instructed EASA to perform a continuous review of the effectiveness of those requirements. The mandate included an assessment of the impact on aircrew alertness of the following Flight Duty Periods (FDPs):

1. Duties of more than 13 hours at the most favourable time of the day; 2. Duties of more than 10 hours at the least favourable time of the day; 3. Duties of more than 11 hours for crew members in an unknown state of acclimatisation; 4. Duties including a high level of sectors (more than 6); 5. On-call duties such as standby or reserve followed by flight duties; and 6. Disruptive schedules.

The review process started in 2017 with the commissioning of a scientific study. In view of the large scope of the task, it was decided to split the set of six FDPs into two groups (FTL#1 and FTL#2). The commissioned study started by ranking the six FDPs according to their potential to induce fatigue, identifying ‘duties of more than 10 hours at the least favourable time of the day’ and ‘disruptive schedules’ as the most fatiguing FDPs, leaving the remaining four FDPs for evaluation in a future study. The comprehensive report on the results of the FTL#1 study3F

4 directly related to the two top-ranking FDPs findings was published by EASA on 18 February 2019. The report points to increased levels of crew fatigue for all night duties as well as for disruptive duties, especially ‘late finishes’. Under RMT.0492, EASA amended the FTL requirements to address the recommendation of the FTL#1 study. An NPA4F

5 was submitted to focused consultation of the ABs in Q3 2023, and the final amendments were adopted in December 2023.5F

6

3 https://www.easa.europa.eu/faq/19202 4 https://www.easa.europa.eu/document-library/general-publications/effectiveness-flight-time-limitation-ftl-report 5 NPA 2023-103. 6 EASA ED Decision 2023/023/R

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In 2021/2022 EASA launched the second phase of the scientific research project (FTL#2), intended to study the effectiveness of the remaining four duties of interest in providing adequate protection from potential consequences of fatigue and, if necessary, make recommendations for improvement. A study of controlled rest in the cockpit was also included; FTL#2 specifically addressed the use of controlled rest and whether it should be promoted as a fatigue mitigation strategy. The results of the study have been published on the EASA website. More details on findings, can be found under action#3 in this document.

In 2023, EASA launched a comparative study to analyse the current national rules legislating FTL for helicopter operations. The study analysed the current rules in 9 EASA MS and 4 non-EASA states. Following this study, a task force was established to produce a concept paper on future shape and concepts for FTL rules for helicopter commercial operations. The concept paper was finalised in 2024; however, RMT.0494 has been put on hold a re-prioritisation of rulemaking activities.

1.3.2 Existing Actions Table 1 – List of current actions

Action number Type. Code

Owner Objective – Intended impacts

RMT .0492 FS.2 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS)

RMT .0493 FS.2 Update and harmonisation of the FTL rules for CAT by aeroplanes for air taxi and single-pilot operations

SPT .0116 FS.2 Supporting the

implementation of appropriate fatigue risk management (appropriate FRM) or a fatigue risk management system (FRMS) by operators and their oversight by competent authorities through the organisation of webinars/workshops/con ferences on specific topics to share information and best practices.

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1.4 List of proposed actions

Based on the SIA and the status of the existing actions, it is recommended to propose the following new actions. Table 2 – List of proposed actions

Action type Owner Objective – Intended impacts MST FS.2 Data collection and analysis related to handling of fatigue

reports, and results of FTL/FRM oversight. SPT FS.2 / SM.1 Provide better guidance to crew, operators and NCA’s on

issues related to fatigue reporting. RM activity FS.2 Improve the regulatory text surrounding controlled rest

in the cockpit. Others (non-EPAS action) NoA Update ECCAIRS taxonomy

1.4.1 Baseline scenario – What would happen if there were no additional actions?

Safety is typically measured by the number of occurrences and fatalities. Even when something goes wrong, accident investigators may find little evidence of fatigue events, except after a deep analysis of flight crew sleep history.

Today the risks arising from crew members fatigue in real operations are being mitigated when the prescriptive FTL is supported by an effective fatigue risk management process. EASA and the Members States’ competent authorities are increasingly looking for strategies to support operators under their oversight better manage aircrew fatigue in everyday operations, at organisational and personal level.

However, without new, or updated, safety actions addressing the safety risks identified in section 1, risks resulting from aircrew fatigue will remain.

1.4.2 Objectives The objectives are to manage and reduce the effects of aircrew fatigue. A simple objective assessment may conclude that the prevalence of aircrew fatigue will never be eliminated, however the principle of reducing safety risks as low as reasonably practicable should drive these actions.

1.4.3 List of proposed actions

While the specific objectives of the actions are detailed in the subsequent sections, the general objective is to develop the best intervention strategy to address the safety issues on aircrew fatigue with safe and efficient measures. Actions 1-5 are actions that have been updated from previous BIS version 2019, while Actions 5,6 and 7 are newly proposed actions.

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Action number #

Action title Action type Action status

1 Event dedicated to FTL/FRM. SPT.0116 Updated existing action

2

RMT.0492 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS) RMT.0493 Update and harmonisation of the FTL rules for CAT by aeroplanes for air taxi and single-pilot operations.

RMT. 0492

RMT.0493

Updated existing action

3 Further actions following study of the effectiveness of FTL - Phase 2 of the research.

NEW Others New proposed action

4 EASA Standardisation - focus on FTL/FRM during OPS standardisation inspections.

STD Updated existing action

5 Provide better guidance on issues related to fatigue reporting NEW SPT New proposed action

6 ECCAIRS Taxonomy Update NEW Others New proposed action

7 Data collection and analysis related to handling of fatigue reports, and results of FTL/FRM oversight.

New MST New proposed action

Assessment of the revised and new actions

1.5 ACTION #1. - Events dedicated to FRM (SPT.0116)

1.5.1 What is the action? Continuing from the success of the conferences held in Vienna in 2024 with the collaboration of Austro Control and in Madrid in 2025 with the collaboration of AESA, more events jointly organised by EASA and a volunteering NAA, will:

• Emphasise to NAAs, stakeholders and aircrew associations that aircrew fatigue is an aviation safety risk that needs to be mitigated to a level as low as reasonably practicable;

• Clarify the need to apply fatigue risk management in addition to prescriptive requirements through the operator’s safety risk management (SRM) process by applying appropriate fatigue risk management principles and tools (appropriate FRM) or through a fully-fledged fatigue risk management organisation structure, policy and procedures (aka FRMS);

• Emphasize the importance of fatigue (risk) management training, from two perspectives:

o aircrew training on their respective responsibilities for compliance with FTL requirements and on individual strategies for proper management of their highly fatiguing duties; and

o training of operators’ management and crew rostering personnel on the implementation of appropriate FRM or FRMS;

• Encourage safety culture, including fatigue reporting culture, and holding of regular surveys among aircrews at MS or operator’s level;

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• Collect feedback.

1.5.2 What will the action achieve?

This safety promotion task has an expected medium safety benefit. It is aimed at continuing to raise knowledge on fatigue risk management methods and tools and the need of dedicated FRM training, the shared responsibility principle, as well as to encourage fatigue reporting culture. As a result, it is expected that aircrew and operators would better understand and discharge their respective responsibilities and commit to an appropriate FRM or FRMS.

1.5.3 What is the technical content of the action? The technical content of the actions will be explanatory material in the form of presentations.

1.5.4 Interfaces to be considered This action requires coordination between EASA and the MS that will volunteer to host an event on their territory. The competent authority of a volunteering State will put in place organisational and logistic measures for the event, while EASA will promote it so that operators and authorities from other States be able to attend.

The hosting MS will be invited to contribute to EASA presentations with their own material or contributions from operators, scientific community and social partners. EASA’s experts will coordinate all presentation materials for the event and answer questions from the participants.

1.5.5 How will the action be monitored?

The effectiveness of the SPT will be monitored through surveys or questionnaires during the events.

1.6 ACTION # 2: RMT.0492 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS) and RMT.0493 FTL rules for CAT by aeroplane for air taxi operations and single-pilot operations taking into account operational experience and recent scientific evidence

1.6.1 What is the action?

RMT.0492 & RMT.0493 already delivered NPA 2017-176F

7, and a focused consultation (NPA 2024-106) in 2024. An Opinion is planned for 2025.

Within RMT.0492 a separate subtask was established to specifically address the recommendations from FTL#1 Study on effectiveness of EU FTL. This subtask was completed with the publication of ED Decision 2023/023/R.

7 https://www.easa.europa.eu/sites/default/files/dfu/NPA%202017-17.pdf

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1.6.2 What will the action achieve?

RMT.0492 & RMT.0493 aim to provide a level playing field across EU for on-demand emergency medical services (EMS) operators and air taxi operators of fixed wing aircraft, proposing a harmonised regulatory approach on the basis of state-of-the-art rules. So far, the regulatory framework in this domain has been patchy, consisting of Subpart Q of Annex III to Commission Regulation (EC) No 859/2008 in combination with various national requirements on FDPs, standby, inflight rest and split duty, which filled the gaps in Subpart Q.

1.6.3 What is the technical content of the action? RMT.0492 & RMT.0493 will produce an Opinion in 2025, which will consider the comments received following the consultations of NPA 2017-17 and NPA 2024-106.

1.6.4 Impact analysis

RMT.0492 & RMT.0493 are supported by an Impact Assessment (IA).

1.6.5 Time implementation Opinion – 2025; implementation 2027.

1.7 ACTION # 3. Further actions following results of the research study of the effectiveness of FTL - Phase 2 (RES.0006).

1.7.1 What is the action?

In 2021/2022 EASA launched the second phase of the scientific research project on the effectiveness of EU FTL (FTL#2) intended to study four duties of interest in providing adequate protection from potential consequences of fatigue and, if necessary, make recommendations for improvement. The research specifically examined four types of potentially fatigue-inducing flight duty periods (FDPs):

• Flight duties exceeding 13 hours, starting in the most favourable time of day;

• Duties longer than 11 hours when crew members’ acclimatization status is unknown;

• Duty periods that include a high number of flight sectors (more than six);

• On-call duties followed by flight operations, especially those not associated with airport standby.

Additionally, the study examined the use of controlled rest during flight duties and the conditions under which flight crew make use of it. Over 300 flight and cabin crew members across eight airlines provided detailed reports on their levels of alertness, fatigue, and sleep during actual duties, offering valuable insight into the human experience behind the regulations.

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1.7.1.1 Findings of the Study

The study highlighted several core findings, which are summarised below: • There is no objective universal measure of fatigue, but subjective assessment tools, while

imperfect, are appropriate for operational field research.

• The current FTL limits are largely effective in managing fatigue risk.

• Duty duration remains the strongest predictor of fatigue, alongside start time, prior sleep quantity, and time awake.

• Limiting either duty duration or number of sectors in isolation is not enough; both must be considered together for fatigue mitigation.

1.7.1.2 Proposals by the research team • Appropriate FRM should be applied for all flight duty periods (FDPs) lasting 10 hours or more, and

for FDPs of 9 hours or more when crew are not acclimatized.

• The existing 18-hour awake time cap should remain, but measures should be taken to ensure crew maximize sleep opportunities before long duties.

• Controlled rest should be used not only in response to unexpected fatigue but also proactively to manage predictable fatigue. A new Acceptable Means of Compliance (AMC) should support this.

• Future studies should address additional topics such as sleep before duty, the effect of combining FDPs, seasonal variations, and standby outside normal daytime hours.

1.7.1.3 Results from study

The results of this second research study, available publicly on the EASA website, have deepened the understanding of fatigue risks in commercial aviation and validated the current regulatory approach.

The study provided a data-driven basis for potential future evolution of the regulatory framework. Future research should examine controlled rest for cabin crew, which was not covered in this study.

While no immediate safety-critical issue has been identified, the insights gained will shape further research needs under Article 9b of Regulation (EU) 965/2012 and guide the next steps in ensuring safe, sustainable aircrew scheduling.

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1.7.2 What will the action achieve? The action will achieve more clarity in terms of controlled cockpit rest as highlighted in the next section.

1.7.3 Description of the activity on controlled rest

In 31% of night flights ≥ 10 hrs pilots used controlled rest in response to unexpected fatigue but also to proactively manage anticipated fatigue. The evolving use of controlled rest was recognized as a positive development, meriting further review and policy development. EASA is proposing to handle the findings of the research as follows - A) Further assessment to be done in the FTL/FRM expert group. If necessary further research could

be proposed on controlled rest, including expanding the scope to cabin crew which was not covered in previous studies, OR;

B) Development of support /regulatory material for controlled rest which may lead to issuance of

best practices, or guidelines for implementation etc. It could also lead to amendment of the current rules, if considered necessary.

1.7.4 Time implementation

Any actions will be taken in line with the established process. After consultation of the above proposal a more accurate timeline will be known.

1.7.5 Implementation cost Depending on the decision this could take up to 0.2 FTE per year over the course of the next years, with some involvement of the stakeholders in the FTL/FRM Expert Group.

Question for the Advisory Bodies

The Competent Authorities and the aviation industry are invited to comment these proposals and express support or otherwise on both actions.

1.8 ACTION # 4. Standardisation on FTL/FRM

1.8.1 What is the action?

EASA conducts standardisation inspections of the MS competent authorities in the air operations domain. Areas inspected usually include FTL/FRM requirements, i.e. already today EASA standardises FTL/FRM implementation. EASA will continue to include the review of FTL/FRM implementation during the programmed standardisation activities, using a risk-based approach. Standardisation results show a relatively high number of non-compliances related to FTL implementation.

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1.8.2 What will the action achieve? This action is intended to prevent incorrect and ineffective implementation of FTL/FRM requirements through focused standardisation and thus achieve a uniform level of implementation across EU.

1.8.3 What is the technical content of the action?

EASA will carry out standardisation inspections based on established plans. The inspections shall be carried out in accordance with Commission Implementing Regulation (EU) No 628/20137F

8, as well as with the approved methodology and tools.

1.8.4 Impact Analysis The impact of this action does not have any measurable qualitative measures. The results of the standardisation activities are considered for future rulemaking or support activities.

1.8.5 Time implementation • Ongoing

1.8.6 Implementation cost • No extra costs are foreseen for the specific action.

1.9 ACTION #5 Provide better guidance to crew, operators and NCA’s on issues related to fatigue reporting. (NEW - SPT-TBA)

1.9.1 What is the action?

This action intends to provide guidance to operators and NCA’s on the issue of fatigue reporting. This topic has been raised at various FTL/FRM Expert group meetings and the FRM conferences in Vienna and Madrid. This action will build on material used during the Covid-19 pandemic.8F

9

1.9.2 What will the action achieve?

This action could provide crew, operators and NCA’s better guidance on:

• Minimum information required by crew to ensure a reporting provides a complete context; • Standardised use of taxonomy to enable a more structured monitoring and analysis of these

in the future; • Risk assessment and processing of fatigue reports by operators;

9 https://www.easa.europa.eu/community/topics/fatigue-management

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• Risk assessment and use of ECRS of fatigue reports by NCA’s; • More homogenous approach to fatigue occurrences in ECCAIRS;

1.9.3 What is the technical content of the action?

The technical content of the action will be either in the form of a Guidance leaflet or other promotional material.

1.9.4 Impact Analysis

This action will increase awareness on the importance of fatigue reporting in a management system. This action will provide more clarity on the follow-up during oversight of the NCA’s.

1.9.5 Time Implementation

Q2 – 2028

1.9.6 Implementation cost

EASA 0.1 FTE for 2027/2028.

1.10 ACTION #6 Update the ECCAIRS taxonomy for fatigue reporting – NEW – NOT AN EPAS ACTION

1.10.1 What is the action? The analysis and monitoring by existing ECCAIRS taxonomy regarding fatigue is limited and does not optimally facilitate this task. Therefore, it is proposed that the existing ECCAIRS taxonomy for event types is amended to better capture fatigue related occurrences and enable a more structured monitoring and analysis of these in the future. Refer to Safety Analysis section 4.5.4 for details. To produce the guidance on the usage of newly proposed and updated taxonomy to facilitate proper implementation (coding). This action is necessary to complement the EPAS actions. EASA will work with the NoA to develop it.

1.10.2 What will the action achieve? Better capture of fatigue related occurrences and improved monitoring and analysis.

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1.10.3 What is the technical content of the action? Updated taxonomy in ECCAIRS system. NOTE – This action may be related to MST.0043 and potentially provide safety promotion inputs to promote good data quality in fatigue occurrence reporting.

1.10.4 Impact Analysis The updated taxonomy should provide better clarity on assessment of fatigue reports. It should also allow a better fatigue data analysis for the safety review. It will support better analysis by using the large language models as well.

1.10.5 Time implementation

The updated taxonomy is expected by Q4 2027.

1.10.6 Implementation cost EASA 0.2 FTE for 2026/2027/2028 plus resources provided by NoA members for this action.

1.11 ACTION #7 Data collection and analysis related to fatigue reports and FTL/FRM oversight. (NEW -MST.TBA)

1.11.1 What is the action?

Data collection through surveys with all the Member State NCA’s related to aircrew fatigue reports and FTL/FRM oversight.

1.11.2 What will the action achieve?

This action could provide the Agency and all stakeholders with information related to:

• NCA FTL/FRM audits and inspection results; • FTL/FRM oversight activities; • The approval/oversight of operator’s appropriate FRM and associated challenges; • The most common non-compliances (operators and NCAs);

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• Information related to prevalence of fatigue reporting in the member states; • Information related to quality and content of fatigue reports. • Standardise approach to ERCS use on fatigue reports (in collaboration with NoA dedicated

working group).

1.11.2.1 Standardised safety performance indicators and metrics on FTL. The action could also complement the work being performed by the Agency on standardisation of Safety Performance Indicators on operational robustness and metrics retrieved from the operators. Performance indicators for operational robustness of rosters should support the operator in the assessment of the stability of its rostering system, but also help the competent authorities in their oversight. The use of consistent standardised metrics could also help the better trending of indicators. It is proposed that a common broad framework and methodology of capturing such data could be used at European level.

1.11.3 What is the technical content of the action?

The technical content of the action will be a survey hosted by the Agency platform. NOTE – This action may be related to MST.0043 and potentially provide safety promotion inputs to promote good data quality in fatigue occurrence reporting.

1.11.4 Impact Analysis

This action is expected to provide quantitative data from NCAs. The survey results could provide an informed decision on future intervention strategy actions.

1.11.5 Time Implementation

Q4 – 2028.

1.11.6 Implementation cost

EASA 0.2 FTE for 2027. MS action is required but this is not quantifiable due to different oversight and data gathering systems.

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1.12 Postponed or Discarded actions

These actions that have been included in the previous BIS version have been either postponed or discarded.

Action title Objective Reason for postponing / discarding it

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Standardisation – Focused on FTL/FRM (Action#4 in previous BIS)

Increase focus of standardisation inspections of the MS.

This action will be embedded in the current action (EASA standardisation). Due to resource constraints no additional FTL/FRM standardisation activities are foreseen to be conducted. FTL/FRM will still be one of the main focus of the standard inspection programme.

Implementation support mechanism dedicated to FTL/FRM (Action#6 in previous BIS)

Provide a support mechanism to NAAs in developing competence of the inspectors in oversight of FTL/FRM.

Action removed as this is part of the strategic priority in EPAS Version 2024 3.1.6.1 where such deficiencies are identified through standardisation. Since the inception of the only one mission has been conducted in 2019 and since then no other NCA has requested such specific support from EASA. This means that SPT.0117 has been partially covered by the publishing of Inspectors Checklists under SPT.0118 and is partially covered by a new SPT under action#6, resulting in the removal of SPT.0117.

Implementation Support (A Workshop) (Action#2 in previous BIS)

Perform a workshop dedicated to NCAs FTL/FRM issues.

This specific action is removed. The support of implementation of appropriate FRM, and other key issues are included under SPT.0116.

RMT.0494 FTL rules for helicopter commercial operations

Action has been put on hold until further review due to prioritization exercise.

RMT.0495 FTL rules for aeroplane commercial operations other than CAT

Action has been put on hold until further review due to prioritization exercise.

Analysis of impacts of proposed actions

1.13 Analysis of impacts

The impact of each action is described within each descriptor in Section 5.

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Best Intervention Strategy

The update of the BIS is necessary to reflect the scenarios that the industry, and consequently all stakeholders, currently face. This is the first update following the recovery from Covid-19, thus some actions in the previous version have been completed or integrated into updated actions, while others have been discarded.

The three pillars (rulemaking, Member State tasks and safety promotion tasks) on which the previous BIS was based are still applicable. The intervention strategy is largely the same, however new actions should deliver a more robust and accurate picture of the issues surrounding aircrew fatigue. This will also promote the continued cooperation of all the affected stakeholders.

The proposed intervention strategy is aligned with the principle that everyone shares a responsibility when dealing with aircrew fatigue. This is fostered through the actions in the EPAS which are, rulemaking, standardisation, Member State actions and safety promotion. The input of the advisory bodies is necessary to ensure that the deliverables of each action are measured for effectiveness.

Addressing aircrew fatigue is crucial for ensuring the safety and well-being of flight personnel. Effective intervention strategies for managing aircrew fatigue involve a combination of operational, organisational, and individual approaches.

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Best Intervention Strategy BIS15 “Aircrew Fatigue (SI-0039)”

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# Action title Action type

Benefit* EASA resources 2025 2026 2027 2028

1 Event dedicated to FTL/FRM.

SPT.0116 Medium Mission budget: 1mission x 1000 euro x 5 experts = 5 000 euros

Conference - Q1

Conference – Q1

Conference - TBD

2

RMT.0492 Development of FTL rules for CAT operations of emergency medical services by aeroplanes (AEMS) RMT.0493 Update and harmonisation of the FTL rules for CAT by aeroplanes for air taxi And single-pilot operations.

RMT. 0492

RMT.0493

High 2025-2027: 0,1 FTE/year

1. Opinion

2. EDD

1. Workshop with AB

3 Further actions following study of the effectiveness of FTL - Phase 2 of the research.

New Others

Medium EASA 0.2 FTE/year TBD

4 EASA Standardisation - focus on FTL/FRM during OPS standardisation inspections.

STD Medium Refer to STD budgets.

Ongoing

5 Provide better guidance on issues related to fatigue reporting

NEW SPT Medium 2026-2028: 0.1 FTE/year

Safety Promotion /

Guidance Documents

6 ECCAIRS Taxonomy Update

NEW Others

Medium 2026-2027: 0.2 FTE/year [More resources to be considered for the full review by the NoA, not limited to EASA resources]

Review by Network of

Aviation Safety Analysts (NoA) and FTL/FRM expert groups

Update of Taxonomy

[provisional timeline – subject to

overall taxonomy updating process]

7 Data collection and analysis related to handling of fatigue reports, and results of FTL/FRM oversight.

New MST Medium 2028: 0.2 FTE Survey to MS

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Best Intervention Strategy BIS15 “Aircrew Fatigue (SI-0039)”

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APPENDIX A – SAFETY ANALYSIS REPORT

Strategy & Safety Management Directorate Safety Intelligence & Performance Department

Safety Analysis Report

Aircrew fatigue

Version 1

< “The information Contained in this report is intended for internal communication and documentation of work in progress. Such information is not necessarily definitive, has not been authorised for distribution outside the premises of EASA and consequently the Agency cannot be held responsible for any damage resulting from unauthorised use of this in formation. If you relay on this information for purposes other than its intended use, you assume all risk associated with such use.”

BIS Aircrew Fatigue (SI-0039) Safety analysis report

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Safety Analysis Report

Aircrew fatigue

Document ref. Status Date Aircrew fatigue (FTL) Version 1 17/12/2024 Contact name and address for enquiries: Aigars Krastins

[email protected] European Aviation Safety Agency Safety Intelligence & Performance Department Postfach 10 12 53 50452 Köln Germany

Information on EASA is available at: www.easa.europa.eu

Authorisation : Name Signature Date

Prepared A. Krastins 22/11/2024

Reviewed 1 C. Taliana 29/11/2024

Endorsed SIRB 17/12/2024

Report Distribution List:

1 SIRB members

2

3

4

5

BIS Aircrew Fatigue (SI-0039) Safety analysis report

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Table of Contents 1 Executive summary ................................................................................................................................... 31

2 Introduction .............................................................................................................................................. 32

3 The problem statement: ........................................................................................................................... 33

4 Analysis ..................................................................................................................................................... 33 4.1 Setting the scene – macro view ....................................................................................................... 33

4.1.1 Fatigue related occurrences overview – all aviation domains and personnel ................... 33 4.1.2 Fatigue related occurrences involving CAT Aeroplanes, all aviation personnel ................ 34 4.1.3 Fatigue related CAT Rotorcraft occurrences ..................................................................... 35

4.2 Fatigue related CAT aircrew occurrences leading to operational events ....................................... 36 4.2.1 Event type analysis ............................................................................................................. 37 4.2.2 Occurrence class ................................................................................................................ 41 4.2.3 Occurrence categories ....................................................................................................... 42 4.2.4 European risk classification scheme .................................................................................. 42 4.2.5 Per State of operator.......................................................................................................... 43 4.2.6 2023 occurrence with operational events – narrative review ........................................... 44

4.3 Focus areas review .......................................................................................................................... 48 4.3.1 Commander’s discretion .................................................................................................... 48 4.3.2 Duty time extension ........................................................................................................... 50 4.3.3 Stand by duty ..................................................................................................................... 51 4.3.4 Rest time less than required .............................................................................................. 52 4.3.5 Tired ................................................................................................................................... 52 4.3.6 Acclimatisation ................................................................................................................... 53 4.3.7 Multiple sector ................................................................................................................... 54 4.3.8 Awake ................................................................................................................................. 55 4.3.9 Long night duty .................................................................................................................. 55 4.3.10 Controlled rest ................................................................................................................... 56

4.4 Conclusions after the occurrence narrative review. ....................................................................... 56 4.5 Proposed actions ............................................................................................................................. 57

4.5.1 To explore other data sources for aircrew fatigue assessment [STD, MST] ...................... 57 4.5.2 To provide guidance for operators and Member State authorities on fatigue related

occurrence processing and ERCS application [MST, SPT.0057] ......................................... 57 4.5.3 Remind and maintain the focus on fatigue, its prevention, and consequences [SPT.0116,

SPT.0117 and SPT.0118] ..................................................................................................... 58 4.5.4 To update the ECCAIRS taxonomy [NoA action] ................................................................ 58

5 Conclusions ............................................................................................................................................... 59

Attachment A: Acronyms and Definitions (Optional – if required) ................................................................. 62

Table of Figures Figure 1: Distribution of fatigue related occurrences and rate per one million flights, all aviation domains, all personnel ......................................................................................................................................................... 34 Figure 2: Distribution of fatigue related occurrences year on year, all aviation domains, all personnel ....... 34

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Figure 3: Distribution of fatigue related occurrences and rate per one million flights involving CAT A operated aircraft, all personnel. ...................................................................................................................... 35 Figure 4: Distribution of fatigue related occurrences involving CAT A operated aircraft, all personnel, year on year. ............................................................................................................................................................ 35 Figure 5: Distribution of fatigue and operational related occurrences involving CAT A operated aircraft, aircrew . ........................................................................................................................................................... 36 Figure 6: Distribution of fatigue and operational related occurrences involving CAT A operated aircraft, aircrew. ............................................................................................................................................................ 37 Figure 10: Distribution of fatigue and operational events (2019-2023) related occurrences per operational event type (list curtailed) ................................................................................................................................ 37 Figure 11: Distribution of fatigue and operational events (2019-2023) related occurrences per operational event type (list curtailed) ................................................................................................................................ 38 Figure 12: Distribution of fatigue and operational events related occurrences per operational event type – unstable approach ........................................................................................................................................... 38 Figure 13: Distribution of fatigue and operational events related occurrences per operational event type – level bust ......................................................................................................................................................... 39 Figure 14: Distribution of fatigue and operational events related occurrences per operational event type – operation of cabin exit – arming/disarming .................................................................................................... 39 Figure 15: Distribution of fatigue and operational events related occurrences per operational event type – operation flight controls .................................................................................................................................. 40 Figure 16: Distribution of fatigue related occurrences and consequential events related occurrences (list curtailed) ......................................................................................................................................................... 40 Figure 17: Distribution of fatigue related occurrences and consequential events related occurrences (list curtailed) ......................................................................................................................................................... 41 Figure 7: Distribution of fatigue and operational events related occurrences involving commercial air transport aeroplanes and aggregated ERCS scores ......................................................................................... 42 Figure 8: Distribution of fatigue and operational events related occurrences involving commercial air transport aeroplanes and aggregated ERCS scores ......................................................................................... 43 Figure 9: Distribution of fatigue and operational events related occurrences per state of operator ............ 44 Figure 18: Operational event types per level 3 and 4. .................................................................................... 46 Figure 19: Key risk areas .................................................................................................................................. 47 Figure 20: Distribution of occurrences per month .......................................................................................... 47 Figure 21: Distribution of organisational events ............................................................................................. 48 Figure 22: Distribution of commander’s discretion keyword related occurrences and rate .......................... 49 Figure 23: Distribution of commander’s discretion keyword related occurrences and event types (list curtailed) ......................................................................................................................................................... 49 Figure 24: Distribution of commander’s discretion keyword and fatigue related occurrences and rate ....... 50 Figure 25: Distribution of commander’s discretion keyword and fatigue related occurrences and event types ......................................................................................................................................................................... 50 Figure 26: Distribution of commander’s discretion keyword and fatigue related occurrences and event types ......................................................................................................................................................................... 51 Figure 27: Distribution of duty time extension related occurrences (list curtailed) ....................................... 51 Figure 28: Distribution of rest time less than required related occurrences and event types ....................... 52 Figure 29: Distribution of rest time less than required related occurrences (list curtailed) ........................... 52 Figure 30: Distribution of tired keyword in headline occurrences .................................................................. 53 Figure 31: Distribution of acclimatisation related occurrences ...................................................................... 53 Figure 32: Distribution of acclimatisation related occurrences ...................................................................... 54 Figure 33: Distribution of multiple sectors keywords in narrative related occurrences ................................. 54 Figure 34: Distribution of awake keyword in narrative related occurrences .................................................. 55 Figure 35: Distribution of awake keyword in narrative related occurrences .................................................. 55 Figure 36: Distribution of controlled rest keyword in headline related occurrences ..................................... 56

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1 Executive summary

Fatigue can negatively affect aircrew performance in the aircraft and pose a hazard to flight safety. In commercial air transport, aircrew rosters are traditionally developed on the basis of prescriptive duty time limits, flight time limits, minimum rest requirements and other constraints such as minimum notification times and prohibition to combine certain duties, to name a few. These limits and requirements, referred to as flight time limitations (FTL), are presumed to be adequate to prevent aircrew from experiencing fatigue at levels that could put at risk the safety of flight operations. This safety issue is included in the CAT Aeroplanes safety risk portfolio under number SI-0039. According to the SIPI score this safety issue is in upper end of medium risk level and requires an assessment. Thus, it was moved from the Step 5 (Monitor) to Step 2 (Assess) as part of the EU Safety risk Management process. The statistics of fatigue related occurrences is reviewed, and analysis provided in this document to support an update of the existing BIS on Aircrew fatigue. Review of occurrences does not allow to assess the detailed elements related to fatigue risk management FRM. For the rostering element, a review at the operator level is needed, most probably as part of the oversight activity. All in all there have been significant number of occurrences reported, coded with fatigue event type value, over the review period from 2019-2023 for all aviation personnel with an increasing trend for the rate, occurrences per one million flights. There is insignificant number of fatigue related occurrences for CAT Rotorcraft operations, thus making impossible to analyse these and derive conclusions. When focusing on the aircrew related fatigue occurrences involving CAT fixed wing aeroplanes, overall a significant increase for both absolute numbers and rates are noticed for 2022 and 2023. From the occurrences identified as aircrew fatigue related over 2019-2023, none of them do classify as serious incident or accident according to the ICAO Annex 13 and R996/2010 in the dataset for CAT fixed wing operations. In terms of risk classification aggregated scores for 100 occurrences with ERCS scored, mainly for 2023 occurrences, the highest risk key risk areas are collision on runway (runway incursion by a vehicle – one occurrence high risk), aircraft upset and airborne collision. There are four states of operator, where more than half of occurrences are stemming from. There could be different reasons for that, good reporting culture being one of them. Unstable approaches has been one of the most common event type, however in terms of ERCS aggregated score, runway incursion by a vehicle, separation minima infringement and configuration warning related are the highest risk ones. Flight delay has been the most common outcome event in terms of number of occurrences, however as per ERCS score, go arounds have been with the highest risk. It is important to note that go-arounds even being risky in their execution are safety nets that allow to repeat an approach for safe landings. Likewise performing a go-around in a state of fatigue could also lead to serious consequences.

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The narrative review of occurrences with fatigue and other operational events (effect on flight safety) in 2023, allowed to confirm some operational consequences or effects on operations, however, out of 316 occurrences, only 155 were confirmed that there was as contribution from fatigue. This makes 21 occurrences per one Million flights. For comparison, the rate for GNSS outages and alterations occurrences in 2023 was 1 700 occurrences per one Million flights. The rate of turbulence encounters with injuries – 97 occurrences per one million flights. At the same time data shows that reporting is differing from one member state to another. For full assessment, information from member states’ oversight activities are needed. For the focus areas, the following can be concluded:

• Commander’s discretion reports have significantly increased for 2022 and 2023 in both absolute numbers and rate. Associated events per numbers and aggregated ERCS score are duty time exceedance and extension.

• Vast majority of Duty time extension related occurrences have been experienced in 2020 during the pandemic.

• Even if the number of occurrences is low, there is a steady increase in occurrences where the term ‘tired’ is mentioned in the headline.

• Long night duty related occurrences, even with low number, have increased when compared with 2019, especially for 2020, 2022 and 2023.

Fatigue does contribute negatively on aviation safety; however, it cannot be taken in isolation. Final conclusions cannot be made, based solely on the European Central Repository data, additional sources of information need to be explored, such as information from authority oversight of the FTL and FRM. The activity of assessment should be repeated once all occurrences since 2023 onwards are ERCS scored by authorities as per regulation.

2 Introduction

This safety analysis report is developed to support EASA review of the BIS for the SI-0039 Aircrew fatigue. This safety issue is included in the CAT Aeroplanes safety risk portfolio. According to the SIPI score this safety issue is in upper end of medium and requires a review as part of the EU Safety risk Management process. Fatigue can negatively affect aircrew performance in the aircraft and pose a hazard to flight safety. In commercial air transport, aircrew rosters are traditionally developed on the basis of prescriptive duty time limits, flight time limits, minimum rest requirements and other constraints such as minimum notification times and prohibition to combine certain duties, to name a few. These limits and requirements, referred to as flight time limitations (FTL), are presumed to be adequate for maintaining aircrew fatigue at levels that will not put at risk the safety of flight operations. Also FRM plays a significant role in containing this contributing issue. The goal of this safety analysis paper is to review aircrew fatigue related occurrences to determine if the FTL and FRM schemes are fit for purpose and adequately contain this contributing issue. To do that, present fatigue related occurrence statistics, trends in the last past years and derive the categories of occurrences presenting a significant safety risk. This includes in particular occurrences contributed by fatigue, caused by commander’s discretion (due to various reasons), acclimatisation, duty time extension, standby duty, long night duty, reduced rest period, rest time less than required, duty time, or related with having flown multiple sectors, getting tired, and controlled rest.

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In this report a distinction between fatigue (accrued over period of time due to lack of sufficient or adequate rest) and tiredness (getting tired by the long day of duty, or a day with many ‘unexpected’ events) is made.

3 The problem statement

Data source: ECR data, extracted on 20.03.2024 Scope: All / CAT fixed wing aircrew related, EASA MS operators Timeframe: 2019-2023 The methods used: Event type factoring and narrative search. Tools used: Power BI. Exposure data used for rates: source Eurocontrol, CAT A internal in, departure from, arrival flights to EASA MS, Excludes Iceland. Not limited to the EU operators. Data quality: contains duplicates, subject to the coding of event type in the occurrence records. Analyse aircrew fatigue related occurrences in the ECR to detect undesirable trends, safety risks and, to extent possible, determine the adequacy of FTL and FRM to contain this contributing issue.

4 Analysis

4.1 Setting the scene – macro view

4.1.1 Fatigue related occurrences overview – all aviation domains and personnel

As shown in the Figure 1 below, in the timeframe from 2019 till end 2023 there have been more than 32 510 fatigue related occurrences registered in the European Central Repository (ECR) across all aviation domains and personnel. After the drop of such occurrences in absolute numbers during years affected by COVID-19 pandemic and associated low activity there has been a statistically significant increase during the recovery periods in 2022 and 2023. In absolute numbers, 2022 the pre-Covid 19 level was almost reached even the activity was lower than in 2019. In 2023 the highest number within the 2019-2023 period of almost 11 000 occurrences was reached. In terms of rate, the peak was also in 2023 (1 526).

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Figure 1: Distribution of fatigue related occurrences and rate per one million flights, all aviation domains, all personnel

The Figure 2 displays the year on year evolution of the fatigue related occurrences. In 2023 almost for all months the absolute numbers of fatigue related occurrences have been higher than in previous periods. In 2023 the peak has been over the summer months.

Figure 2: Distribution of fatigue related occurrences year on year, all aviation domains, all personnel

4.1.2 Fatigue related occurrences involving CAT Aeroplanes, all aviation personnel

There are around 26 170 fatigue related occurrences, involving CAT Aeroplanes operations, all aviation personnel. As shown in Figure 3, both the absolute numbers of occurrences and rate have increased and exceeding the 2019 level since 2022. Also the rate has been elevated since 2021 onwards with the peak in 2023 with 1 300 occurrences per one million flights.

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Figure 3: Distribution of fatigue related occurrences and rate per one million flights involving CAT A operated aircraft, all personnel.

In Figure 4 year on year situation is reflected. Also for CAT fixed wing fatigue related occurrences in absolute numbers have significantly exceeded the number of previous years. In 2023 also the increase during the summer months is more prominent than in previous years.

Figure 4: Distribution of fatigue related occurrences involving CAT A operated aircraft, all personnel, year on year.

4.1.3 Fatigue related CAT Rotorcraft occurrences

The ECR was reviewed also for aircrew fatigue related occurrences involving CAT Rotorcraft operations. However, there was insignificant number of four occurrences retrieved that does not allow further analysis of these occurrences.

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4.2 Fatigue related CAT aircrew occurrences leading to operational events

In this chapter we take a closer focus on the aircrew fatigue related occurrences, which could have influenced the safety of operations. For an example, there has been an unstabilised approach, level bust, flat/slat speed exceedance and others, contributed by fatigue. All in all there have been more than 800 occurrences in the data set, when fatigue event type was associated with another operational event type. Figure 5 reflects the distribution of fatigue and operational events related occurrences over years in absolute numbers and rate. Years 2022 and 2023 are elevated for both values in comparison with previous years. The rate for 2023 has almost doubled when compared with 2019.

Figure 5: Distribution of fatigue and operational related occurrences involving CAT A operated aircraft, aircrew .

Figure 6 displays the year on year statistics of fatigue and operational related events in the tome period. In 2023 there has been an increase of such occurrences during the spring. In other years most occurrences occurred during the summer months. The interruptions of the e.g. dark blue and orange lines show months without reported occurrences.

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Figure 6: Distribution of fatigue and operational related occurrences involving CAT A operated aircraft, aircrew.

4.2.1 Event type analysis

The majority of operational events potentially associated with fatigue related occurrences have been Unstabilised approaches, Flight level deviations – level busts, Cabin exit – Arming/Disarming, and operation of flight controls. In some cases the following events have occurred that should be highlighted: flat/slat speed exceedance, communication by flight crew with ATC, clearance deviations, configuration setting errors, speed control related, deep/hard landings, loss of separation, fuel management related, performance calculations related, stop bar crossing and others.

Figure 7: Distribution of fatigue and operational events (2019-2023) related occurrences (list curtailed)

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Figure 11 presents the event types associated with the highest risk occurrences as per aggregated ERCS score. The runway incursion by a vehicle (not relevant for the aircrew fatigue, however), separation minima infringement and configuration warning related are the highest risk ones.

Figure 8: Distribution of fatigue and operational events (2019-2023) related occurrences per aggregated ERCS score (list curtailed)

Figure 12 reflects the absolute numbers and rate for unstabilised approaches events. The highest rate was in 2022. In 2023 there is a slight decrease.

Figure 9: Distribution of fatigue and operational events related occurrences per operational event type – unstable approach

Figure 13 highlights the absolute number and rate for fatigue related level busts, there the increase for both absolute numbers and rate.

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Figure 10: Distribution of fatigue and operational events related occurrences per operational event type – level bust

Figure 14 highlights the increase of absolute numbers and rate for operation of cabin exit – arming/disarming cases.

Figure 11: Distribution of fatigue and operational events related occurrences per operational event type – operation of cabin exit – arming/disarming

Figure 15 shows also the increase for operation of flight controls issues.

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Figure 12: Distribution of fatigue and operational events related occurrences per operational event type – operation flight controls

Fatigue has contributed and may contribute to significant operational events.

4.2.1.1 Consequential events analysis

Now we take a closer look at the consequential events encountered in occurrences with fatigue contribution. As per Figure 16, in most cases there has been a flight delay. This consequence might have been also a reason for fatigue. Regarding the operational safety related outcomes in more than 50 cases there has been a landing executed after unstabilised approach. Also rejected landings and take- offs, delayed rotation, approaches below weather minima, and others. Medical incapacitation of a cabin crew has occurred in 32 cases.

Figure 13: Distribution of fatigue related occurrences and consequential events related occurrences (list curtailed)

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However as per Figure 17, in terms of aggregated ERCS score, for the scored occurrences, the highest risk consequential event type has been go-around, followed equally by flight crew impairment – and requiring a mayday call. It is important to note that go-around even risky in its execution is a safety barrier that allows to repeat an approach for a safe landing.

Figure 14: Distribution of fatigue related occurrences and consequential events related occurrences per ERCS aggregated score

(list curtailed)

4.2.2 Occurrence class9F

10

Almost all fatigue related occurrences, with effects on operations, have been classified as incidents in the European Central Repository (ECR) in the timeframe of 2019-2023. In the ECR, there have been 4 occurrences classified by EASA Member State authorities as serious incidents in the timeframe 2019-2023 in the dataset for CAT fixed wing operations. However, after review, none of these 4 could be confirmed as serious incidents as per ICAO Annex 13 and R996/2010. This is a data quality issue in the ECR. There is one serious incident that occurred in early 2024 and the investigation is ongoing. Fatigue elements are normally included in the final reports of the safety investigation authorities. Based on preliminary information, this serious incident was an air proximity occurrence with TCAS Resolution Advisory triggered. ATCO fatigue had contributed to it (the night before he slept about 3 hours, that the quality of his sleep was low, that he had been sleeping for about 1 month with reduced hours of sleep compared to what is usual for him and with low quality, due to personal situation, the shift was morning shift and his chronotype is morning), no information about the flight crew fatigue. Thus this serious incident is outside the scope of this safety issue assessment.

10 The classification of the occurrence in relation to its severity.

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4.2.3 Occurrence categories10F

11

Majority [560] occurrences are categorised as Other occurrence category that is used to categorise an occurrence that does not fall in any other occurrence category. It is followed by Navigation error [133] occurrence category and then by Cabin safety events related. Around 20 occurrences have had occurrence categories Abnormal runway contact, Airprox/ACAS alert/loss of separation and around 13 Loss of control inflight.

4.2.4 European risk classification scheme

Now we will look at occurrence distribution per aggregated ERCS – European Risk Classifications Scheme numeric values, to see the risk levels of occurrences within the period covered. It is worth mentioning that ERCS scoring became applicable as of January 1, 2023 according to COMMISSION IMPLEMENTING REGULATION (EU) 2021/2082. It is premature to make a full analysis based on the ERCS aggregated scores, as this was becoming applicable as of Jan 2023, but nevertheless the information is included there. This exercise can be repeated in the next years. 709 occurrences (88%) out of 809 do not have ERCS score assigned. Thus ERCS is not expected to be completed for occurrence records prior this date. Figure 7 shows the absolute numbers of occurrences per year versus the aggregated ERCS scores for occurrences having this value filled. The highest risk events occurred in 2023.

Figure 15: Distribution of fatigue and operational events related occurrences involving commercial air transport aeroplanes and aggregated ERCS scores

11 The occurrence categories as developed by CAST/ICAO Common Taxonomy Team (CICTT). Commercial Aviation Safety Team [CAST] and International Civil Aviation Organization" [ICAO]. Each category has a unique name and identifier to permit common coding in accident/incident systems, a text definition, and usage notes to further clarify the category and aid in coding occurrences. An important element of the occurrence category design is that it permits the association of multiple categories with an occurrence. Multiple coding supports the primary focus of CICTT- accident PREVENTION, in which every pertinent element should be investigated, recorded, and analysed. Based on version October 2013 (4.6)

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Figure 8 displays the distribution of fatigue and operational events related occurrences per key risk area and aggregated risk score, when this value is present in the database. Here we can see that the highest key risk area per aggregated ERCS score is Collision on runway to which fatigue has or may have had contributed to. This is the result of one occurrence of runway incursion by a gardening vehicle. The second is aircraft upset stemming from 39 occurrences (flap/slat speed exceedances, unstabilised approaches, control of manual flight path, deviation form airspeed). The 3rd is airborne with aggregation from 12 occurrences (separation minima infringements, level busts, flight crew deviations from SID, data entry, operation with wrong altimeter setting).

Figure 16: Distribution of fatigue and operational events related occurrences involving commercial air transport aeroplanes and aggregated ERCS scores

4.2.5 Per State of operator

The Figure 9 shows the distribution of occurrences per state of operator involved in these occurrences. The majority of all fatigue related occurrences in the analysis involved Spanish operators (26%) and Sweden (13%) followed by Belgium, Germany, and Switzerland that would cover more than half of all occurrences. Around 50% of all occurrences are stemming from 4 states of operator. This could imply that reporting culture as well as practices to integrate fatigue related occurrences within the ECR are widely differing among the EASA member states (some states are integrating all fatigue related occurrences, some partially, some not at all).

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Figure 17: Distribution of fatigue and operational events related occurrences per state of operator

4.2.6 2023 occurrence with operational events – narrative review

A close review of occurrence narratives that occurred in 2023 was done, to get in immersive picture of how many of all the occurrences are confirmed to be contributed by ‘fatigue’ and which have an operational consequence. In 2023 there were 316 occurrences (without duplicates), with operational events coded in the ECR. However, only 155 (or 49%) occurrences could be clearly attributed to the ‘fatigue’ event. That makes the rate of 21 occurrences per one Million flights. For comparison, the rate for GNSS outages and alterations occurrences in 2023 was 1700 occurrences per one Million flights. The rate of turbulence encounters with injuries – 97 occurrences per one million flights. In 124 (or 39%) occurrences, ‘fatigue’ could not be directly not confirmed by the narrative text. These include cases, where crew reported to be tired or mentioned fatigue as a side factor (not a direct contributor), and others. This confirms the complexity of analysing fatigue reports based solely on text that may not provide a complete picture. Fatigue reporting is in the end a personal issue. The narrative text could only provide a narrow picture of the event leading to an occurrence or the person choosing to submit a report. Furthermore, the comparison above represents a simple but not inter-related comparison to other current major events affecting aviation safety. GNSS outages and turbulence encounters are events that are not susceptible to subjective assessments.

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The Table 1 shows the distribution of the 155 occurrences per event type level 1. Note that one occurrence may be assigned with more than one event type. The total shows the number of occurrences, not the number of assigned event types.

Table 3: Occurrences per event type level 1.

Figure 18 lists presents the operational events per levels 3 and 4 that provide the right level of granularity to assess the event types. The occurrences contributed by fatigue that had resulted in aircraft handling issues (control of both automated and manual flight path, high rate of climb/descent, landing deep, etc.), Flight crew operation of equipment aspects (operation with incorrect altimeter setting, operation of flight controls, radio frequency error, operation of engine controls, fuel management, data entry error, configuration setting error), flight crew ATC clearance deviation (flight level/altitude deviation – level bust, hold short clearance deviation, landing clearance deviation). Regarding the flight crew/ATC communication – there have been occurrences of prolonged loss of communication. Various issues with preflight planning. Several parameter exceedances, such as flap/slat exceedance, landing gear down airspeed exceedance, or airspeed exceedance. Also deviations from intended airspeed. Apron/ramp incursion, airborne conflicts (loss of separation). For cabin crew – cabin safety related aspects contributed by fatigue have been cabin exit arming/disarming related, cabin/cockpit communication.

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Figure 18: Operational event types per level 3 and 4.

In Figure 21 the distribution of occurrences per key risk areas are presented. Majority of occurrences, namely 80% do not have key risk area assigned by competent authorities of the member states. For the 31 (20%) occurrences with key risk area assigned, majority is leading towards runway excursions, aircraft upset and other injuries.

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Figure 19: Key risk areas

Figure 20 shows the distribution of occurrences per month. There had been three peeks in March, January and July.

Figure 20: Distribution of occurrences per month

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Figure 21 displays the distribution of events for 2023 fatigue related occurrences with effects on operations. In 16 occurrences issues related with flight crew staffing and scheduling, including cabin crew as reported.

Figure 21: Distribution of organisational events

4.3 Focus areas review

In here the following focus areas will be reviewed: Commander’s discretion, Duty time extension, Stand by duty, Rest time less than required, Tired, Acclimatisation, Multiple sector, Awake, Long night duty, and Controlled rest. These are stemming from the EASA SIB on traffic disruptions during summer, standardisation feedback, and identified factors from occurrences and discussions from subject forums.

4.3.1 Commander’s discretion

To analyse the occurrences for the fatigue related occurrences having the commander’s discretion component, the headline search for commander’s discretion keywords was applied. The query returned close to 500 such occurrences for the review period. Figure 22 shows a step for 2022 and retaining it in 2023 for both absolute numbers and the rate.

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Figure 22: Distribution of commander’s discretion keyword related occurrences and rate per one Million CAT IFR flights.

Figure 23 lists the event types associated with commanders discretion related occurrences. Majority of events have been Organisational events like duty time extension, duty time exceedance, crew below regulatory required minimum, or rest time less than required. Also in terms of ERCS, two highest are duty time extension, duty time exceedance event related scored occurrences. Most of consequences have been flight delays. Personnel related events mainly are fatigue related. Operational events that may have triggered the commander’s discretion, have been unexpected weather encounter, passenger boarding, closure of the aerodrome, performance calculations and windshear/microburst encounters related. Majority of these occurrences have been reported by Swedish, German and Irish operators.

Figure 23: Distribution of commander’s discretion keyword related occurrences and event types (list curtailed)

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Taking a closer look at commanders discretion occurrences [29] with fatigue element in Figure 22, we can see that there has been an increase in 2023, when compared with previous years.

Figure 24: Distribution of commander’s discretion keyword and fatigue related occurrences and rate

Figure 25 provides the distribution of event types for commander’s discretion and fatigue related occurrences. There again the majority are Duty time extension related. Also Flight crew staffing and scheduling is appearing.

Figure 25: Distribution of commander’s discretion keyword and fatigue related occurrences and event types

There is a need for competent authorities to review and operators to be aware of the adequate use of ‘commander’s discretion’ – so it is not already foreseen in the roster planning and scheduling but is really used for unforeseen circumstances.

4.3.2 Duty time extension

If we look at the duty time extension related occurrences that cover the authorised or unauthorised extension of a person`s duty time, there have been more than 4100 such occurrences. Figure 26 reflects that there have been a significant step during the COVID-19 period of 2020. All the other years are comparable.

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Figure 26: Distribution of commander’s discretion keyword and fatigue related occurrences and event types

Figure 27 shows the event types encountered along the duty time extension. These have been mostly fatigue related. But also flight delay and flight crew staffing and scheduling related have occurred.

Figure 27: Distribution of duty time extension related occurrences (list curtailed)

Even there is a significant number of these occurrences, occurrences with operational consequences have been very limited.

4.3.3 Stand by duty

To retrieve standby duty related occurrences, headline search by relevant keyword was performed. There has been an insignificant number of such occurrences of 3 over the review period. In terms of events, these were flight crew staffing and scheduling related.

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4.3.4 Rest time less than required

The rest time less than required by regulations occurrences amounting to 184 records has been distributed almost homogenously over the review period.

Figure 28: Distribution of rest time less than required related occurrences and event types

Figure 29 highlights the associated events of the rest time less than required related occurrences. The majority has been fatigue related coming from flight crew staffing and scheduling, duty time exceedance, and duty time extension.

Figure 29: Distribution of rest time less than required related occurrences (list curtailed)

4.3.5 Tired

In this report a distinction between fatigue (accrued over period of time due to lack of sufficient or adequate rest) and tiredness (getting tired by the long day of duty, or a day with many ‘unexpected’ events) is made. In 92 occurrences tired has been mentioned in the headline. In 2022 the levels of 2019 were reached. However, 2023 has had a step to more than double of such occurrences when compared with 2019.

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Figure 30: Distribution of tired keyword in headline occurrences

4.3.6 Acclimatisation

Acclimatisation involves occurrences involving crossings of multiple time zones. For the review period close to 70 occurrences were retrieved from the ECR that have been related with acclimatisation. According to Figure 31 majority of events occurred in 2019.

Figure 31: Distribution of acclimatisation related occurrences

In terms of events, as per Figure 32, majority are fatigue flight crew staffing and scheduling and circadian disruption related.

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Figure 32: Distribution of acclimatisation related occurrences

It is worth noting that majority of these occurrences occurred in Japan and US in outstations, as well in Spain and Denmark.

4.3.7 Multiple sector

The dataset was also filtered by multiple sector keywords in the narrative. There have been a low number of 32 occurrences meeting this criterion. Figure 33 shows that this phenomenon has been more prominent in 2019, prior the COVID-19 pandemic. Multiple sector situations can mostly lead to being tired than fatigued (provided that all the sectors flown do not exceed FTL). In the latest years this type of occurrences have occurred 6 to 5 times in 2022 and 2023 respectively.

Figure 33: Distribution of multiple sectors keywords in narrative related occurrences

The associated event types for these occurrences were mainly fatigue related, caused by several technical failures, and consequentially resulting in diversions, aircraft return etc.

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4.3.8 Awake

The dataset for the review period returned more than 1000 occurrences where awake keyword was found in the narrative. For both in terms of absolute numbers and rate the 2022 and 2023 are below 2019 levels.

Figure 34: Distribution of awake keyword in narrative related occurrences

Majority of occurrences have been fatigue related. Then followed by organisational ones that are duty time extension and flight crew staffing and scheduling related.

4.3.9 Long night duty

The data set returns low number of 30 occurrences that are having the long night duty keywords in the headline. As it is shown in Figure 35, in terms of rate, it is elevated when compared with 2019 however well below the rate experienced in 2020.

Figure 35: Distribution of awake keyword in narrative related occurrences

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4.3.10 Controlled rest

For controlled rest keyword in the headline 25 occurrences were retrieved.

Figure 36: Distribution of controlled rest keyword in headline related occurrences

Here the majority of events were fatigue related. In one case there has been a prolonged loss of communication. From the narrative: CM1 feeling very tired and experiencing micro sleeps so implemented OMA 8.3.10.3.3 procedure for controlled rest for 30 mins. At end of controlled rest CM1 took a physiological break, stretched in the galley and used a hot towel to assist in combatting sleep emerita. CM1 returned to the flight deck, settled in and declared ready for duty and resumed PM duties. On handover, CM2 took the opportunity while SCCM was in the flight deck to also take a physiological break. CM1 was fully alert during this period, wearing headset but had not re-activated the VHF1 comm output. After approximately 4 mins, due to apparent quietness, CM1 requested radio check from Maastricht with no response, the VHF1 selector was found to be in the wrong position, normal communications were resumed following a second radio check with the switch in the correct position. CM2 returned shortly afterwards, during the re-brief, an ACARS message printed asking us to contact Maastricht. His had already been accomplished and frequency changed to Copenhagen control. It may be prudent to supplement the OMA with a checklist of ergonomic and anthropometric items that will be in non-standard positions during controlled rest, for example seating position for approach, comms setup, and display settings. A formal brief on position, changes, local traffic and changes in Meteorology at destination and alternate may also assist in resumption of situational awareness.

4.4 Conclusions after the occurrence narrative review.

First of all there is an apparent issue with the way occurrence reports are being handled by the states, as the practices of whether to include these occurrences in the ECR or not varies from one Member State to

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another. Data is not always clear and make it challenging to understand the underlying factors or causes for the fatigue from information available in the European Central Repository. This implies that from this data analysis it is not possible to determine if existing scheduling practices, FRM processes or and FTL requirements are fit for purpose and are averting the situation that aircrews are taking up duties while being fatigued, additional information is needed, such as information from the authority oversight activities. Furthermore, it is evident that from the content of submitted fatigue reports is not possible to clearly deduce the contributing factors. Also, reporting culture and openness for aircrews to report ‘fatigued’ needs to be assessed in a wider context within an operator – is this tolerated or there are possible direct or indirect repercussions.

4.5 Proposed actions

The following mitigating actions or recommendations are proposed as an outcome of this assessment.

4.5.1 To explore other data sources for aircrew fatigue assessment [STD, MST]

4.5.2 To provide guidance for operators and Member State authorities on fatigue related occurrence processing and ERCS application [MST, SPT.0057]

There is a lack of more homogenous approach for integration of the fatigue related occurrences in the European Central Repository by all competent authorities. Some Member States integrate all occurrences, some integrate parts, some do not integrate at all. Also the information available in the occurrence records is lacking the required level of detail to understand the outcomes of the investigation and analysis of those occurrences that do not allow to validate if present FTL and FRM provisions are sufficient to address this contributing safety issue. Follow up information is also not always available in the records. The ECR records are also subject to the level of data quality that is ensured by the MS authorities, namely the event types coded, and narratives updated, lack of European Risk Classification Scheme being applied. All this, limits the possibilities to derive final conclusions on this topic and require additional sources of information to be reviewed, such as outcomes of the oversight activities in the area for FTL and FRM, with an especial focus on scheduled rosters versus the executed ones, in order to spot systemic issues at the rostering level, such as multiple sectors with little or no margin for delays, long night duties, consideration of trainings and other preceding duties, etc. The use of EASA FTL/FRM INSPECTOR’S CHECKLIST, SUPPORTING MATERIAL FOR NAAs INSPECTORS, 2024 could be of use to collect such an information. The guidelines should also include the review if ‘commander’s discretion’ is being properly applied – so that it is not already foreseen in the roster planning and scheduling but is really used for unforeseen circumstances. See also: ORO.FTL | EASA

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4.5.3 Remind and maintain the focus on fatigue, its prevention, and consequences [SPT.0116, SPT.0117 and SPT.0118]

To remind the aviation community about the fatigue risk, necessity to comply with the FTL rules, not to schedule to the maximum, promote open reporting of fatigue, ensure that aircrews are involved in operations only when they are fit for duty (not fatigued). Difference between being fatigued and being tired after a long day, needs to be educated to the aviation community.

4.5.4 To update the ECCAIRS taxonomy [NoA action]

The analysis and monitoring by existing ECAIRS taxonomy regarding fatigue is limited and does not optimally facilitate this task. Therefore, in this chapter the existing ECCAIRS taxonomy for event types is listed and new/modifications are proposed to better capture the fatigue related occurrences and enable a more structured monitoring, analysis of these in the future. This will facilitate a better monitoring of fatigue related occurrences and analyse them in the future. This is an initial proposed list that needs a review in a wider FRM/FTL experts group. The present value ‘Fatigue - Events involving an individual or a crew/team collectively being affected by fatigue’ needs to be improved towards: Personnel  Physiological Events  Personnel Alertness and Fatigue Events: Existing in the taxonomy:

• Fatigue [proposal to deactivate] New (proposed):

• Fatigue – flight crew member • Fatigue – cabin crew member • Fatigue – air traffic control officer (ATCO) • Fatigue – technician or mechanic • Fatigue – ground handling employee • Fatigue – other aviation personnel • Fatigue affecting performance – flight crew member • Fatigue affecting performance – cabin crew member • Fatigue affecting performance – air traffic control officer (ATCO) • Fatigue affecting performance – technician or mechanic • Fatigue affecting performance – ground handling employee • Fatigue affecting performance – other aviation personnel • Tired – flight crew member • Tired – cabin crew member • Tired – air traffic control officer (ATCO) • Tired – technician or mechanic • Tired – ground handling employee • Tired – other aviation personnel • Tired, performance affected – flight crew member • Tired, performance affected – cabin crew member • Tired, performance affected – air traffic control officer (ATCO) • Tired, performance affected – technician or mechanic • Tired, performance affected – ground handling employee • Tired, performance affected – other aviation personnel • Tired due to multiple sectors flown • Fell asleep, micro nap, microsleep (related)

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Organisational  Regulatory  Personnel Regulatory Events: Existing in the taxonomy:

• Duty Time Exceeded • Duty Time Extension • Rest Time Less than Required

New (proposed): • Stand by duty related aspects: Stand by duty not counted in the FTL, retrospective change of stand

by duty, stand by duty swapped to split duty, last minute change from late to early stand by duty, conflicting stand by duty, etc.

• Commander’s discretion – pressure to apply: Pressure to apply Commander’s discretion, or Commander’s discretion already included in the roster planning.

• Commander’s discretion – proper application • Controlled rest applied or used – Controlled rest procedure is a countermeasure to manage

unexpected fatigue, and it is organised by the commander, if workload permits. • Controlled rest misused – improper application of controlled rest. Controlled rest procedure is a

countermeasure to manage unexpected fatigue, and it is organised by the commander, if workload permits.

• Disturbance outside stand by duty times: Operational control contacting the crewmembers outside the rostered stand by duty times.

Organisational  Organisational Management Flight Operational Management: Existing in the taxonomy:

• Flight Crew Staffing and Scheduling (An event related to the planning and scheduling of flight crew (includes cabin crew))

Amend (proposed): • Flight Aircrew Staffing and Scheduling and Rostering (An event related to the planning, scheduling,

and rostering of flight crew (includes cabin crew)) New (proposed):

• Aircrew rostering – multiple sectors scheduled: Multiple sectors scheduled with no or limited margin for delays or unforeseen circumstances.

• Aircrew rostering – long night duty scheduled: Long night duty scheduled that may contribute to the fatigue or tiredness.

5 Conclusions

There have been no aircrew fatigue related occurrence confirmed to be a serious incident or accident (2019- 2023) according to the ICAO Annex 13 and R996/2010 in the dataset for CAT fixed wing operations. When focusing on the aircrew related fatigue occurrences involving operations with CAT fixed wing aeroplanes, overall a significant increase for both absolute numbers and rates are noticed for 2022 and 2023. There is insignificant number of fatigue related occurrences for CAT Rotorcraft operations, thus making impossible to analyse and derive conclusions. Considering that the number of safe flights taking off, and a rate of 21 confirmed fatigue related occurrences for aircrew per one million flights in 2023, the situation in general could be perceived to be under control. But this may be a misleading conclusion as it is subject to reporting culture and data quality of the records in the ECR. To conclude, the rostering and its execution (planned vs executed) review at the operator level is needed, as part of the oversight activity by competent authorities.

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All in all there has been a significant number of occurrences, reported over the review period from 2019- 2023 and coded with ‘fatigue’ event type, with an increasing trend for the rate, occurrences per million flights for aviation personnel covering all domains. In terms of risk classification aggregated scores for 100 occurrences with ERCS scored, mainly for 2023 occurrences11F

12, the highest risk key risk areas are collision on runway (runway incursion by a vehicle – one occurrence high risk), aircraft upset and airborne collision. This shows that fatigue have negative effects upon actors’ abilities and vigilance and normally exacerbates the situation or contributes to errors and lapses. Unstable approaches have been one of the most common event type, however in terms of ERCS aggregated score, runway incursion by a vehicle, separation minima infringement and configuration warning related are the highest risk ones. Flight delay has been the most common outcome event in terms of number of occurrences, however as per ERCS score, go arounds have been with the highest risk. It is important to note that go-around even risky in its execution is a safety net that allows to repeat an approach for a safe landing. There are four states of operator, where the more than half of occurrences are stemming from. What about others? There could be different reasons for that, good reporting culture being one of them. The occurrence narrative review for 2023 occurrences with operational events, shows that there have been 21 occurrences per one Million flights, where fatigue played a role to the safety of operations, that in comparison to the GNSS outages and alterations that were around 1700 occurrences per one Million flight in the same period. The full-scale analysis of the European Risk Classification is not possible yet, as only 20% of these occurrences have the ERCS score. For the focus areas, the following can be concluded:

• Commander’s discretion reports have significantly increased for 2022 and 2023 in both absolute numbers and rate. Associated events per numbers and aggregated ERCS score are duty time exceedance and extension.

• Vast majority of Duty time extension related occurrences have been experienced in 2020 during the pandemic.

• Even as the number of occurrences is low, there is a steady increase in occurrences where the term ‘tired’ is mentioned in the headline.

• Long night duty related occurrences, even with low number, have increased when compared with 2019, especially for 2020, 2022 and 2023.

All in all, it can be concluded that fatigue is a factor that does contribute negatively on aviation safety. It cannot be taken in isolation, as fatigue facilitates errors introduced by aircrews. However, the quality level of information in occurrence records in the European Central repository is rather poor, follow-up information missing, and underlying factors for the causes of the fatigue are challenging or even impossible to be derived. This implies that for a complete assessment, additional information is needed, such as information from the oversight activities on FTL/FRM. Refer to the action in 4.4.1.

12 The requirement to apply the ERCS classification on all occurrences in the ECR is applicable since Jan 1, 2023.

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It is also recommended to remind and maintain focus on fatigue, its prevention, and consequences, see chapter 4.4.2. To facilitate the better analysis of fatigue related occurrences, ECCAIRS taxonomy needs to be updated with relevant values that are proposed in chapter 4.4.3. The activity of assessment should be repeated once all occurrences since 2023 onwards are ERCS scored by authorities as per regulation, as well as using fused data in the D4S.

European Union Aviation Safety Agency – EPAS 2023 – 2025

Best Intervention Strategy “Aircrew Fatigue”

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Attachment A: Acronyms and Definitions (Optional – if required)

ECR – European Central repository of occurrences

EPAS preparation – 10/12/2025

Safety Issue Assessment “Fatigue in non-aircrew personnel (SI-3005)”

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APPENDIX B – SAFETY ISSUE ANALYSIS “SI-3005 Fatigue in non-aircrew personnel”

1. Executive Summary

Note on bundling the Safety Issues related to fatigue:

SI-3005 addresses fatigue across all aviation personnel other than flight and cabin crew. By contrast, SI-0039 focuses exclusively on flight and cabin crew within the FTL/FRM regulatory framework. The two SIs are complementary and intentionally form a total system approach: SI-0039 concentrates on aircrew specific rules and oversight, while SI-3005 targets cross domain culture, technology, scientific evidence and implementation support for non-crew roles. Activities should be coordinated to avoid duplication.

Summary of the Safety Issue Assessment 1 Problem Problem 1: Apart flight and cabin crew having currently dedicated rules, and

to a lower extent ATCOs, there is no policy to support the other aviation domains to address the fatigue safety risks. Problem 2: This can be reflected by the fact that >58 000 ECCAIRS occurrences linked to fatigue were reported between 2019 and 2025, where about 52 000 do not have sufficient information on fatigue. There is a problem of data reliability to face if we want to manage the safety risks appropriately. Indeed, Regulation (EU) No 376/2014 requires reporting of any occurrence that may represent a significant risk. Problem 3: For non-aircrew personnel, this number of occurrences might be the sign of a problem for which its criticality cannot be yet addressed adequately.

2 Stakeholders Non-aircrew personnel, for instance: Aerodrome operators; ATM/ANS providers; ATSEP; CAW entities Part-145, Part- CAMO and Part-CAO; ATO/DTO; FSTD operators; ground handling organisations; Apron management service providers ; flight operations officers/dispatch.

3 ESC Decision It was decided that problem 2 (lack of data reliability for non-aircrew safety event) is the most prominent issue to tacle in priority. It was concluded to work on taxonomy refinements (linked to BIS15 “Aircrew Fatigue” action 6) and clearer guidance for those coding fatigue occurrences for non-aircrew personnel. It is proposed to use the current Member States Tasks for these purposes: o MST.0002 Promotion of SMS o MST.0043 Improvement of data quality in occurrence reporting

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Table of contents Executive Summary .................................................................................................................................... 63

1 Safety Issue Assessment ...................................................................................................................... 65

2 Baseline scenario-– What would happen if there is no additional action? ......................................... 73

3 Intervention objectives ........................................................................................................................ 73

4 Proposed actions .................................................................................................................................. 74

5 Conclusion ............................................................................................................................................ 77

6 SIA Appendix 1 ..................................................................................................................................... 78

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2 Safety Issue Assessment

2.1 Introduction and purpose

The EASA Safety Risk Management process aims to manage aviation safety risks in an integrated manner, with the objectives of:

1. Prioritising safety actions which are most efficient in reducing risk levels 2. Ensuring adequate internal and external coordination on both key aspects of the Safety Risk

Management, which are: • The identification and assessment of safety issues, • Identifying existing mitigating actions, and • The programming of safety or mitigating actions

3. Providing transparency on why the Agency takes certain actions

In order to achieve these objectives, the Agency has established structured links between safety intelligence processes (safety analysis and performance) and safety action related processes (integrated programming, rulemaking, certification, organisations oversight, standardisation, safety promotion, corrective action in reaction to a safety problem/operational directives). These links should foresee the need for an assessment of both the risks levels associated to certain safety issues, and an assessment of the efficiency of intended safety actions, in order to enable prioritization. The scope is here limited to global or systemic safety issues that may affect European aviation products, services, or European passengers. A safety risk portfolio is the domain specific, common repository for recording and documenting the outputs of the above mentioned tasks. Within the Human Factors Safety Risk Portfolio, the safety issue ‘fatigue and quality of sleep’ has been raised. This paper documents the safety issue assessment carried out by the Assessment Team. It provides data and expert judgement, in addition to making specific recommendations regarding how best to manage this safety issue. This supports the governing bodies of the SRM process in their evaluation of the need for safety actions.

2.2 Definition of the Safety Issue

Fatigue is defined by ICAO as ‘a physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase, and/ or workload (mental and/ or physical activity) that can impair a person’s alertness and ability to perform safety related operational duties.’12F

13 Sleep quality is defined by ICAO as the ‘capacity of sleep to restore waking function. Good quality sleep has minimal disruption to the non-REM13F

14/REM cycle. Fragmentation of the non-REM/REM cycle by waking up, or by brief arousals that move the brain to a lighter stage of sleep without actually waking up, decreases the resporative value of sleep.’ Fatigue is repeatedly identified as one of the most serious challenges within the industry. The signs of fatigue are subtle and will lower human performance. The aviation industry relies on competent, trained, rested people that are physically and mentally fit to perform their duties to ensure safety and efficiency. The nature and amount of work, the physical and emotional environment, opportunities to rest and the quantity and quality of sleep all affect fatigue levels. The management of fatigue levels requires that:

13 ICAO DOC 9966 Manual for the Oversight of Fatigue Management Approaches 14 Rapid eye movement

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• Organisations provide the conditions, facilities and guidance to support their employees to be fit for duty; and

• Individuals take responsibility for using their rest periods and other activities to be fit for duty and report to their organisation if they feel that they are, or will become, unfit for duty.

• This is enabled by the organisation having a positive safety culture

Amongst the conditions provided by organisations is the ability for employees to predict or plan ahead in terms of working time and free time, enabling individuals to plan their private life and manage their rest effectively. Although technologies are increasingly becoming available to assess fitness for duty, organisations and individuals need to use these with caution. Such measures must be validated, both scientifically and for the operational context in which they are being applied. Examples include performance vigilance tests, online cognitive testing, personal wrist worn activity monitors, mobile apps, physical assessments (wobble boards), task-load assessment, computer fatigue modelling software, as well as numerous other methods. It is often said that individuals are poor judges of their own physical and mental state, but if an individual is reporting unfit these tools should not be used to claim otherwise. Despite extensive regulations and guidance on fatigue, it remains one of the most commonly raised issues when discussing human performance. In addition, quality of sleep, wellbeing is less well regulated than the duration of a rest period, or duty time limits. Therefore, its contribution to fatigue and the means of ensuring quality of sleep should be considered. Social connectivity, family time and predictable work schedules are all important contributors to fatigue. Many, many reports have been written regarding fatigue and the status of fatigue regulations. However, while the science of fatigue is well-established and regulations are in place nationally and internationally, it is still being raised as a safety issue, not only by the HF CAG, but by the domain CAGs, not only within EASA but also within the industry as a whole. Why does fatigue remain an issue in domains where specific fatigue regulations are limited or absent? What are the obstacles to minimising fatigue as an issue for aviation professionals? Regulations are developed in collaboration with those they affect and those who will have to implement them. Organisations operate within practical, financial and safety constraints. These constraints and inputs to regulations create inevitable trade-offs with the scientific basis on which the regulations should be based. Equally, if the scope of fatigue regulations is expanded without an exploration of the effectiveness of the regulatory approach, then the same issues are replicated elsewhere. More broadly, continuing cost pressures, staffing constraints and operational volatility can create incentives - organisational and individual - that unintentionally normalise extended duty patterns or insufficient recovery. Trade-offs also exist in personal management of fatigue, and the absence of a means of monitoring this means that this can often be the area where blame for fatigue is placed. However, personal privacy, trust, safety culture and national culture are all difficult to overcome. Methods of objectively measuring fatigue and the ability to predict the impact of fatigue on human performance are improving, which may help to make fatigue management more effective. They may also help to demonstrate to people when they are fatigued, since individual perception is subjective, thus providing greater acceptance of what the science is telling us. What is now needed are some pan-professional recommendations, which can be embedded in safety management, on how to manage fatigue.

2.3 Who is affected?

Within EASA remit, the scope covers aerodrome operators under Regulation (EU) 139/2014 with explicit SMS obligations; ATM/ANS providers subject to Regulation (EU) 2017/373, which sets management system (SMS) requirements and ATSEP competence provisions; and CAW entities Part-145, Part-CAMO and Part-

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CAO where management system duties are embedded in the framework. It also includes training organisations (ATO/DTO) and FSTD operators, which operate under management/quality systems with safety elements (with FSTD governed by CS-FSTD), as well as ground handling organisations brought under the new EU rules (2025/20 and 2025/23) with competent authority oversight and the related Air Ops amendment (2025/24) aligning operator responsibilities. In addition, some functions are addressed through certified entities SMS and interfaces rather than direct certification: apron management service providers are covered via the aerodrome framework (procedures and SMS under Regulation (EU) 139/2014) and flight operations officers/dispatch are addressed through the air operator SMS (Part-ORO), including their interaction with ground handling as clarified by the 2025 Air Ops amendment.

2.3.1 Global analysis

ECCAIRS contains 58 205 occurrences from 2019 to 2025 where fatigue is coded. At the outset of the analysis, it was established that the representation of fatigue across operational domains could not be reliably assessed for datasets exceeding 52 000 records. Additional verification was performed to determine whether the Aviation Sector field could help clarify the operational context of the fatigue coded occurrences but the result came back with approximately 97 % of entries blank. The lack of detail highlights the limited availability of contextual information in occurrence data and reinforces the need to interpret fatigue through the event type coding structure rather than by sector.

Data as of 28/10/25 Filtered by Event_Type_L1 (is Personnel), Event_Type_L4 (is Fatigue), Year (is less than or equal to 2025), Year (is greater than or equal to 2019)

Given these limitations, the subsequent analysis further focuses via the event types (L1-4) on identifying how fatigue is represented across different operational domains.

2.3.2 In-depth analysis Analysis of ECR data for 2019–2025, filtered for all occurrences where fatigue was coded anywhere in the event chain, provides three key insights:

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Fatigue is almost exclusively recorded as a “Personnel” event only Among 58 205 fatigue coded occurrences ‘Personnel’ was the only consistently coded event type. An additional event type was present in 7-12% of the records, allowing partial inference of originator domain in those cases. For the remaining >52 000 records, no structured field permits originator attribution; proportions of flight vs non-flight reporters could possibly (if an indication is present) be derived by manual review or post-hoc recoding, which was not performed.

• This pattern reflects that most of the time reporters and analysts are capturing the observable fatigue symptom without linking it to its operational or organisational contributors.

• Capturing the observable fatigue symptom mostly without linking it to its operational or organisational contributors suggests that many fatigue entries originate from direct self initiated reports or front line observations, which are less likely to include contextual coding14F

15.

Data as of 27/10/25 Filtered by Year (is less than or equal to 2025), Year (is greater than or equal to 2019), _Fatigue (is not (Blank) or 0) Systemic and organisational signals are nevertheless visible across domains 4 376 occurrences in addition to Personnel, also include Organisational coding, mainly under Organisational Management (3 478) and Regulatory (982). Within Organisational Management, fatigue is associated with:

• Flight ops management (2 281) • ATM ops management (1 172) • Maintenance ops management (15) • Aerodrome ops management (7) • Production ops management (2) • Design ops management (1)

15 In safety analysis, “under-coding of contextual factors” is a known phenomenon. Literature on HF taxonomies (e.g. HFACS, Reason’s model) notes that analysts tend to document proximal human actions over latent organisational conditions unless guidance or training explicitly requires multi-level coding.

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Implication - data suggest that fatigue is recognised as part of broader organisational and oversight responsibilities across multiple domains, though analysts or reporters do not always apply the appropriate event types or cross links when entering fatigue related data. As a result, the data under represent how often fatigue is connected to organisational or operational causes, even though such links may exist in practice.

Data as of 27/10/25 Filtered by Year (is less than or equal to 2025), Year (is greater than or equal to 2019), _Fatigue (is not (Blank) or 0)

Operational level coding reinforces this cross-domain presence 2 166 occurrences, in addition to Personnel and Organisational, also include Operational coding and further connect fatigue to:

• Aircraft Flight Operations (1 876) • Air Navigation Services (298) • Aerodrome Operations (132) • Aircraft Maintenance (28) • Aircraft Design (25) • Aircraft Production (1)

Implication – besides flight operations, fatigue related risk appears in ANS, aerodrome and maintenance, design and production operational processes.

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Data as of 27/10/25 Filtered by Year (is less than or equal to 2025), Year (is greater than or equal to 2019), _Fatigue (is not (Blank) or 0)

Summary: Analysis of 58 205 fatigue-coded occurrences (2019–2025) shows that all contain a Personnel → Physiological → Fatigue entry, with about 88 % recorded only at this level and roughly 12 % cross-coded with Organisational, Operational or Consequential event types. This reflects a recognised reporting pattern in ECCAIRS 2, where front line or self initiated reported events do not include the appropriate event types or cross links when entering fatigue related data. As a result, the data underrepresent how often fatigue is connected to organisational or operational causes, even though such links may exist in practice. The pattern where majority of the records are coded only under Personnel, does not mean that fatigue occurs only at the individual level but it reflects the tendency to document the immediate human symptom without linking it to the broader organisational or operational context. The limited contextual data nonetheless reveal fatigue signals under Organisational and Operational categories across domains including ATM, aerodrome and maintenance. Overall, the evidence indicates that fatigue is documented mainly at the individual level and occurs across multiple domains.

2.4 Assessment methodology

The team spent several meetings identifying the main barriers to preventing fatigue in the operational environment, focusing on organisational culture and the potential for implementing new technology. In addition, in the Task Team safety issue assessment of fatigue in the context of the COVID-19 pandemic, a bow-tie model was developed. Many of the issues identified via the bowtie analysis (Annex 1) are still valid in the current operational context.

The principle data source for this issue was the European Central Repository. For >52 000 fatigue coded occurrences the operational domain cannot be reliably determined without manual narrative review or post-hoc recoding and even then may remain unknown if the reports do not state the role of the originator. The graph below therefore presents fatigue reports in aggregate across domains.

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SI- 3005 Data as of 29/9/25

Studies, reports and articles reviewed for this safety issue assessment are listed below:

• EASA report ‘Effectiveness of Flight Time Limitation’, published 28th February 2019

• Research project into the effectiveness of Flight Time Limitation (FTL), delivered on 1 April 2025. Details of this project can be found here.

• ‘Scheduled napping as a countermeasure to sleepiness in air traffic Controllers’, Signal, T.L., Gander, P.H., Anderson, H. and Brash, S. (2009), Journal of Sleep Research, 18:11-19.

• ‘Effects of pre-sleep simulated on-call instructions on subsequent sleep’, Wuyts, J., De Valck, E., Vandekerchove, M., Pattyn, N., Exadaktylos, V. Haex, B., Verbraecken, J. and Cluydts, R. (2012), Biological Psychology, 91:383-388.

• ‘Activity trackers: Can they really help you get fit?’ https://www.health.harvard.edu/blog/activity- trackers-help-you-get-fit-2017102312594

• ‘Fitness for duty: A 3 minute version of the Psychomotor Vigilance Test predicts fatigue related declines in luggage screening performance’ M. Basner, J. Rubinstein (2011) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3190077/

• ‘3-minute smartphone-based and tablet-based psychomotor vigilance tests for the assessment of reduced alertness due to sleep deprivation’ D. Grant, K. Honn, M. Layton, S. Riedy, H. Van (2016) Dongen https://link.springer.com/article/10.3758/s13428-016-0763-8

2.5 Risk assessment of the scenarios

The scenario posited for the safety issue assessment is that fatigue management is difficult to implement to a high standard. The reasons for this were identified via discussion in the group and via a review of occurrence reports, evidence was supplied for these reasons and solutions were proposed. In this sense, if the safety issue assessment were presented as a bow-tie model, the hazard would be poor fatigue management implementation, with the threats being the reasons identified and the proposed solutions as barriers.

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It should be noted that the fatigue task team established as a result of the COVID-19 safety risk portfolio developed a bow-tie model for fatigue in the context of operating in the pandemic. This bow-tie model and its accompanying recommendations remain valid 18 months later. The report prepared by the task team has been published on the EASA website and is available here. The bow-tie model is available in annex 1 to this SIA. List of problems Rules/ regulations can be interpreted differently by different actors Where fatigue related provisions are newer or less explicit, organisations can lawfully arrive at very different practices (e.g. compressing permissible duties into short periods versus distributing them more evenly to protect recovery), especially in highly seasonal roles. This variability is compounded by uneven occurrence reporting practice in ECCAIRS as fatigue contributors are often recorded under operational event types or left in narratives, so signals are missed when queries rely on narrow fields. To resolve this issue, existing regulations and responsibilities need to be better explained. Additional guidance on the intent and means to comply with what is required should be developed. Fatigue Management is a medium to long term investment Fatigue management requires data, monitoring and adjustment. The benefits are therefore not always immediate relative to the cost of the initial investment, which may include the cost of data collection and analysis, reduced working hours or constraints to rostering/ scheduling of staff and recruiting staff for fatigue management. Only after this investment will the gains of FRMS and increased business flexibility be realised. To resolve this issue, we should clarify the intent of applicable requirements and how they should be applied in non-crew contexts and issue concise compliance guidance with examples. Support organisations with reporting aids so fatigue factors are captured consistently under Regulation (EU) 376/2014 and the organisation management system to improve both oversight and comparability without creating new rules. All actors in the system are involved (or need to be involved) in fatigue management The notion of shared responsibility is central to fatigue management. Fatigue in the work place cannot be isolated from personal fatigue and personal responsibility, personal life has to go hand in hand with organisational decisions, rostering and human resources. Everyone need to understand the intrinsic dependabilities of professional decisions, organisation of work and personal decision personal choices. Lack of understanding of the technologies that are becoming available to objectively monitor fatigue Technologies that objectively monitor fatigue are starting to become available. In order for these to provide a positive effect on fatigue management, they need to be properly understood by users. It can be difficult for organisations and individuals to appreciate the capabilities and limitations of such tools, leading to the risk of inadvertent misuse or simply not using the tools to their full capability.

2.6 Existing Actions

The EU rules and actions relating to fatigue that have been published in the EPAS are limited so far to flight and cabin crew. The rulemaking tasks concerning the development or update of flight and duty time limitation (FTL) rules for flight crew are not considered here, as the recommendations in this Safety Issue Assessment (SIA) do not relate to the Aircrew domain. Ongoing activity and new proposed actions addressing flight crew fatigue are in BIS15 “Aircrew fatigue SI-0039”. Apart from the Regulation (EU) 2017/373 and the ATCO Fatigue Study which aims to assess the effects resulting from the implementation of the regulation (https://www.easa.europa.eu/en/domains/air-traffic- management/atmans-workforce-air-traffic-controller-%28ATCO%29-fatigue) there are no other ongoing EPAS actions or studies specifically addressing fatigue in other domains.

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3 Baseline scenario-– What would happen if there is no additional action?

It is not possible to forecast changing levels of fatigue and the future risks posed by fatigue without speculation. However, looking at the issues identified, if no additional action were to be taken then the following situations may evolve:

1. With current ECCAIRS fatigue related reporting practice, the understanding of fatigue risk will remain incomplete and largely limited to individual level data. The current practices capture the presence of fatigue but very rarely its operational or organisational context. We know that fatigue is present in occurrence data (58 205 records since 2019) but we do not know where in the system it originates or how it interacts with organisational and operational factors (>52 000 records lacking context). This limits the ability to detect emerging fatigue trends across domains and to prioritise effective mitigation actions.

2. Where fatigue management expectations are not explicit for non-crew domains, differing interpretations can emerge. Under commercial pressure some organisations may adopt minimal practices, creating an uneven playing field. The EU principle of a level playing field should guide consistent expectations and oversight for non-crew fatigue management within SMS. Without targeted support on what effective fatigue risk management looks like for non-crew roles, organisations tend to meet only a minimum standard. Ongoing guidance that translates the latest science into practical, role-specific measures is needed so that FRM within SMS is applied optimally and consistently across non-crew personnel. In the absence of information regarding the joint responsibilities of the employer and employee in managing fatigue, there will continue to be a disconnected and thus sub-optimal approach to managing fatigue.

3. There is a growing market for objective sleep monitoring tools, such as apps and smart watches. With no interventions, there will be a lack of guidance on the proper use of these tools, their capabilities and limitations. It is very likely that the use of these tools will bring benefits to individuals, but misuse of these tools also bears the risk that personnel could be fatigued without realising.

In a fundamental sense, if no action is taken, nothing in the system will change. The nature of the fatigue issue is that it is affected by social changes as well as aviation system change. As such, risks may increase outside of the control of the aviation regulatory framework.

4 Intervention objectives

The overall objective of the interventions are to reduce the risks posed by fatigue for non-aircrew personnel, through reducing both its prevalence, severity and the severity of the potential consequences of fatigue. Specifically, the proposed actions seek to:

• Ensure that individuals have a reliable, objective means of monitoring their personal fatigue;

• Ensure that organisations have the right organisational culture and management accountabilities, so that:

o fatigue risk management is a normal activity and is used to support safe, efficient and effective operations;

o individuals are able to report fatigue without fearing negative consequences;

o organisations know when and how to react to rising fatigue levels

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• Ensure that scientific advances in predicting and objectively identifying fatigue are able to be incorporated into organisations’ fatigue management programmes;

• Ensure that fatigue considerations are systematically embedded in existing requirements (e.g. occurrence reporting under Reg. (EU) 376/2014 and SMS obligations) by the authorities and organisations so application and oversight are thorough, consistent and evidence based.

5 Proposed actions

5.1 List of proposed actions

Action

number Action title Issue Objective Type of

action (RMT,

SPT, RES, MST)

Scenario number to which it is

linked (where applicable)

1 Guidance on fatigue monitoring apps and smart technology

Apps and ‘smart’ technology exists to warn individuals that they may be fatigued, but they have strengths and limitations that the user must be aware of and understand.

Ensure that individuals can benefit from the technology that exists, while guarding against over-reliance or misuse.

SPT 4

2 Promote and educate positive organisational culture and behaviour to senior managers

Organisational cultures that are negative prevent reporting of human performance related issues, such as fatigue.

Ensure that senior managers establish positive organisational cultures that are robust even in times of crisis and ensure occurrence coding with appropriate information to assess fatigue events.

SPT 3, 2

3 Develop material to support implementation of fatigue requirements in the Member States

Consistent and good quality application of fatigue management in organisations can be supported by regulatory oversight.

Ensure that good practices surrounding fatigue, including those not explicitly referencing duty time limitations or fatigue management (e.g. occurrence reporting and

SPT 1

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safety management) are applied and overseen in a thorough and consistent manner.

4 High quality, regular reviews of scientific advances in prediction and identification of fatigue.

Scientific advances in the prediction and identification of fatigue continue to be made, but it can be challenging for organisations to identify good quality and up to date material.

Ensure that scientific advances in predicting and objectively identifying fatigue are able to be incorporated into organisations’ fatigue management programmes, by publishing regular and high quality reviews of the available science.

RES (on the basis that this is a more in- depth and science led activity than an SPT).

2

5.2 Detailed definition of proposed actions

Guidance on fatigue monitoring apps and smart technology There is a proliferation of fatigue monitoring apps and smart technology, but users need to be aware of the strengths and limitations of this technology in order to use it safety and effectively. Keeping on top of the latest developments and ensuring that aviation professionals are using technology of a suitably high standard is not an easy task for individuals. As a result, it is recommended that an inventory of currently available technology, its strengths and limitations is developed, maintained and promoted to aviation professionals. This action should be comprised of four steps:

1. Development of criteria with which to assess fatigue monitoring technology 2. Assessment of currently available technology 3. Safety promotion of the technology 4. Regular update of the assessment and the safety promotion material

Promote and educate positive organisational culture and behaviour to senior managers By definition, organisational culture is slow to change. However, senior managers can lead changes to organisational culture and behaviours. Organisational culture training courses aimed at senior managers are already in development, therefore this safety promotion aims to promote the need for such senior management knowledge, skills and attitudes (competence) in the area of fatigue management. As such the SPT needs to outline that:

• fatigue risk management is a normal activity and is used to support safe, efficient and effective operations. Fatigue risk management systems are a medium to long term investment, requiring investment in both establishing and maintaining the FRMS, in equipment or software and personnel, in ensuring that the system is integrated in the overall safety management system and as such is updated in alignment with the SMS.

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• Because the determination of whether an individual is fatigued is subjective and rests solely with that individual, fatigue reporting is always a voluntary act. This is in spite of the fact that occurrence reports relating to fatigue are mandatory under Regulation 376/201415F

16. Therefore, if an organisation is to manage fatigue adequately, it must also ensure that individuals are able to report fatigue without experiencing negative consequences.

• Levels of fatigue in an organisation can change for a variety of reasons and these are not only related to the aviation working environment, but also external circumstances. Effective fatigue monitoring not only needs to establish whether levels have changed and define acceptable limits, but also identify circumstances where they should have changed but haven’t, and why. Accountabilities and decision-making processes should be clearly defined in advance, rather than waiting for the situation to arise and wondering what to do.

Develop safety promotion material to support implementation of fatigue requirements in the Member States Consistent and good quality application of fatigue management in organisations can be supported by regulatory oversight. Since fatigue management interfaces with other regulatory requirements, such as Management Systems and occurrence reporting, the full scope and meaning of fatigue management needs to be properly outlined. The safety promotion material should outline not only the scope and meaning of requirements relating to fatigue, but it should also show the relationships between different requirements. Information should also be included regarding fatigue management in different domains and how these might be applied in organisations that employ different types of aviation professional. Finally, the means of overseeing the application of fatigue related requirements and of viewing all the different explicit and implicit requirements as a whole should be outlined and then described in detail. Consideration should be given to auditing techniques and the assessment of organisational culture, since fatigue management may be nicely documented but poorly applied. High quality, regular reviews of scientific advances in prediction and identification of fatigue. Scientific advances in the prediction and identification of fatigue continue to be made, but it can be challenging for organisations to identify good quality and up to date material. Expert knowledge and ample time are resources that are simply out of reach for many organisations. In order to ensure that scientific advances in predicting and objectively identifying fatigue are able to be incorporated into organisations’ fatigue management programmes, EASA should initiate a research study to first establish a high quality review of the available science. This review should include:

• The current established understanding of fatigue identification and prediction

• The most recent advances in the field, along with a critique of the studies so that their conclusions, uncertainties, strengths and weaknesses are clear to the reader.

• A summary of what the new and old information means in combination, including what can and can’t be concluded. Guidance on how the information can be used.

This review should then be updated annually, such that it remains useful and relevant.

16 See Commission Implementing Regulation (EU) 2015/1018

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Best Intervention Strategy “Aircrew Fatigue”

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6 Conclusion

It was decided that lack of data reliability for non-aircrew safety event is the most prominent issue to tackle in priority, and then the scope of actions like safety promotion tasks may be assessed. It was concluded to work on taxonomy refinements (linked to BIS15 “Aircrew Fatigue” action 6) and clearer guidance for those coding fatigue occurrences for non-aircrew personnel. It is proposed to use the current Member States Tasks for these purposes:

• MST.0002 Promotion of SMS • MST.0043 Improvement of data quality in occurrence reporting

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Best Intervention Strategy “Aircrew Fatigue”

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SIA Appendix 1

TE.GEN.00101-005 An agency of the European Union

Postal address: Postfach 10 12 53

50452 Cologne, Germany

Visiting address: Konrad-Adenauer-Ufer 3

50668 Cologne, Germany

Tel.: +49 221 89990 5089

E-mail: [email protected]

Web: www.easa.europa.eu

ISO 9001 Certified Page 1 of 1

Christopher Holgate-Romanov Head of Department SM.2 Strategy and Safety Management Directorate

CHO/DPE/SM.2 Cologne, 12 December 2025

Subject: Consultation of draft Best Intervention Strategy reports

Dear Advisory Bodies’ Members, Alternates and Observers,

The Best Intervention Strategy (BIS) is a tool to support the prioritisation of new actions in the European Plan for Aviation Safety (EPAS) by analysing their potential benefits and costs.

Three BIS reports are attached to this letter:

• BIS06 Airborne Collision Risk: this report provides a brief update of the previous BIS and is shared for information.

• BIS15 Aircrew Fatigue Risks: this report updates the previous BIS and includes new proposed actions on which your comments are expected.

• BIS43 Inadequate Management of Repetitive Defects: this report informs on ongoing actions includes new proposed actions on which your comments are expected.

You are kindly invited to comment on the reports using in the attached templates by 27/03/2026. Please send your feedback to [email protected]. A dedicated template is provided for each BIS topic.

Disclaimer: BIS actions timelines are indicative. They could be amended depending on the priority assigned and the availability of resources.

We thank you for your contribution to the BIS and the EPAS programming exercise.

Yours faithfully,

Christopher Holgate-Romanov

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Summary of the Safety Issue Assessment 1 Problem The inadequate management of repetitive defects was identified as a contributing factor to a number

of fatal and non-fatal accidents of large aeroplanes in commercial air transport and classified as one of the upper-end medium priority safety issues of the airworthiness safety risk portfolio.

While deferred defects and carried forward defects are defined in the continuing airworthiness regulation, the current regulations do not clearly define repetitive defects. Repetitive defects (examples in Annex A chapter 7) can furthermore be difficult to identify and rectify, and root causes thereof have the potential to remain latent over long periods of time. They may eventually affect the safe operation of aircraft, particularly when combined with other defects, or when they occur on highly integrated systems, potentially impacting on automation and/or on flight crew workload.

2 Criticality SIPI 5.79 in 2024 Category: Mitigate/Define TST: No

3 Stakeholders Competent Authorities, Continuing Airworthiness Maintenance Organisation (CAMO), Maintenance Organisation

(MO), Combined Airworthiness Organisation (CAO), Aircraft Operators (Flight crew)

Summary of the Impact Assessment (Options and their impacts) 4 a. The option “No policy change” is not recommended due to the identified safety risks

b. Proposed actions

Indicative timeline

Years Up to end 2025 2026 2027 2028 2029

SPT SAFE 360 2024

Creation of EASA webpage

n/a (but SP material remain available)

SI monitoring to assess

improvement or new issues

MST n/a Start of oversight focus

Continuation and end of oversight focus

n/a

Feedack from CAs and stakeholders from SPT and MST

RMT (GM) Draft GM in NPA 2025-XX (Q4)

RMT.0735

Consultation (stakeholders

comments)

Final GM update (also based on MST

feedback) and EDD publication

GM implementation

Impact between -10 (very negative) and +10 (very positive)

RMT Comment MST Comment SPT Comment

Affected stakeholders

Primary target CAMOs, CAs CA inspectors CAMOs, MOs, pilots

Final outreach Maintenance licence staff CAMOs, MOs, CAOs Maintenance licence staff, NCA staff, airline pilots

Impact per criteria and overall impact per action

Safety impact 5

It will provide clarification on repetitive

defects, identification, and management

thereof (not limited to reliability programme

as it is today)

5

It will raise the focus of

competent authorities oversight

activities to ensure repetitive

defects are effectively managed.

This focus is expected for the next

oversight cycle.

3

It will enable to share good practices

from industry and regulatory

stakeholders on how repetitive

defects are identified, monitored,

resolved, and documented as a key

safety risk, as part of their SMS.

Medium postive Medium postive Low postive

Economic

impact -

overall

0

Extremely low resources impact at EASA level

and potential benefits to be materialised at a

later stage for CAMOs and MOs.

0 Oversight focus integrated in the

current oversight workload -0.5

Minor workload impact on EASA side,

neutral impact on stakeholders

EASA

resources

Negli

gible

1 to 2 weeks to develop the GM

requirements

Neglig

ible

Oversight focus integrated in the

current oversight workload

Very

low

EASA SPT team with few hours from

CAW experts contribution

Stakeholders

resources

Negli

gible

The GM may create very minor additional

work with its implementation in the CAMOs

and MOs. This will be compensated by

potential efficiency benefits (versus an

inefficient management of repetitive defect).

Neglig

ible

Oversight focus integrated in the

current oversight workload

Neutr

al

It is a safety promotion material to

be used when beneficial by the

stakeholders

Overall score 5 Medium positive impact 5 Medium positive impact 2.5 Low positive impact

Action #01 Action #02 Action #03

Guidance material for repetitive defects Oversight of CAMOs and AMOs on the

management of repetitive defects

Good practices on managing repetitive

defects

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Decisions 5 BIS team

proposal

Best Intervention Strategy: the 3 combined actions are proposed to mitigate the “repetitive defects” safety

risks. Action 2 and 3 would pave the way to the Action 1. Indeed the focused oversight and the best

practices promoted will be key enabler for the subsequent implementation of the necessary Guidance

Material providing the missing definition on management of repetitive defect (Action 1, rulemaking in

progress in 2025). The combination of these actions will maximise the impacts of the individual actions.

6 ESC before AB 5.1 BIS consultation for Advisory Bodies: Yes (ESC 7/11/2025)

5.2 ExCom to arbitrate on resources before BIS consultation: No

7 AB feedback Positive or negative feedback? Which BIS actions are amended?

8 ESC decision

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Table of contents Annex A: SIA SI-9001 Inadequate management of repetitive defects .............................................................. 4

1 Safety issue assessment ............................................................................................................................ 5

2 Baseline scenario – What would happen if there is no additional action? ............................................. 24

3 Intervention objectives ............................................................................................................................ 24

4 List of proposed actions........................................................................................................................... 25

5 Conclusion ............................................................................................................................................... 27

6 SIA APPENDIX A - Regulatory materials review ....................................................................................... 28

7 SIA APPENDIX B - Accidents and serious incidents investigation reports review ................................... 32

8 SIA APPENDIX C - Repetitive defects ECR dashboard (dated 20.09.2023) .............................................. 54

9 SIA APPENDIX D - Delphi study results .................................................................................................... 55

10 SIA APPENDIX E - SenseMaker engagement results ............................................................................ 59

11 SIA APPENDIX F - Bowtie diagram ....................................................................................................... 72

Annex B: Detailed definition of the proposed actions .................................................................................... 74

1 RM - Development of guidance material for repetitive defects ............................................................. 74

2 MST - Oversight of CAMOs and AMOs to ensure repetitive defects are effectively managed ............... 74

3 SPT - Promotion of good practices on managing repetitive defects ....................................................... 75

Annex C: Safety impacts assessment............................................................................................................... 76

1 General introduction for Attachements C and D..................................................................................... 76

2 Safety impact methodology .................................................................................................................... 76

3 Results of the safety impact assessment per subcriteria ........................................................................ 77

4 Subcriteria#1 - Direct expected Safety Impact ........................................................................................ 77

5 Subcriteria#2: Additional safety impacts on other Safety Issues ............................................................ 80

6 Subcriteria#3: Relevant Domain Outreach .............................................................................................. 81

7 Subcriteria#4: Enhancing Monitoring Capacity ....................................................................................... 82

Annex D: Economic impacts assessment ......................................................................................................... 83

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Annex A: SIA SI-9001 Inadequate management of repetitive defects

Executive Summary

1. Why intervene?

The inadequate management of repetitive defects was identified as a contributing factor to a number of fatal and non-fatal accidents of large aeroplanes in commercial air transport and classified as one of the top medium priority safety issues of the airworthiness safety risk portfolio. While deferred defects and carried forward defects are defined in the continuing airworthiness regulation, the current regulations do not clearly define repetitive defects. Repetitive defects can furthermore be difficult to identify and rectify, and root causes thereof have the potential to remain latent over long periods of time. They may eventually affect the safe operation of aircraft, particularly when combined with other defects, or when they occur on highly integrated systems, potentially impacting on automation and/ or on flight crew workload. The assessment of this safety issue was launched to review the current European regulation and industry practices regarding repetitive defects, with the overall aim at identifying actions to improve the management of repetitive defects at European level, thereby mitigating the associated risk. It is important to note that the scope of this safety issue specifically focuses on identification, monitoring and resolution of repetitive defects on a daily basis.

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1 Safety issue assessment

1.1 Introduction and purpose

The management of repetitive defects has been identified as one of the top medium priority safety issues of the airworthiness safety risk portfolio (safety issue transferred from the commercial air transport large aeroplanes safety risk portfolio in 2023). Investigation reports of fatal and non-fatal accidents of large aeroplanes in commercial air transport identified repetitive defects as contributing factors. While deferred defects and carried forward defects are defined in the continuing airworthiness regulation, the current regulations do not clearly define repetitive defects. Repetitive defects can furthermore be difficult to identify and rectify, and root causes thereof have the potential to remain latent over long periods of time. They may eventually affect the safe operation of aircraft, particularly when combined with other defects, or when they occur on highly integrated systems, potentially impacting on automation and/ or on flight crew workload. The management of repetitive defects involves multiple domains including continuing airworthiness management, aircraft maintenance, flight operations, and design. This translates into additional challenges, such as information sharing, communication, or interpretation issues, which can ultimately impact how well repetitive defects are managed and hence potentially threaten flight safety. The purpose of this safety issue assessment (SIA) was threefold:

− identifying and reviewing the current regulatory requirements, industry standards and any guidance material related to repetitive defects in the EU, as well as some of other ICAO member states around the world;

− capturing the experience of industry stakeholders to better understand if the current practices sufficiently mitigate the safety risks posed by the repetitive defects and management thereof;

− proposing mitigating actions derived from the assessment of plausible threats and consequences associated with repetitive defects impacting on flight safety.

1.2 Definition of the safety issue

The safety issue addresses repetitive defects of aircraft systems/ structure which may adversely affect aircraft operations and airworthiness if not managed properly. Managing repetitive defects requires a multi-dimensional and collaborative approach between all stakeholders in the airworthiness domain, including operators, design approval holders, continuing airworthiness management and maintenance organisations. Continuing Airworthiness Management Organisations (CAMO) hold the main responsibility in managing such defects. Their role, as prescribed by Regulation (EU) No 1321/2014, is to ensure the airworthiness of the aircraft and arrange the rectification of defects. Identification of repetitive defects is a challenge, as well as their technical assessment and resolution. The CAMO interfaces with all other involved organisations. Aircraft Maintenance Organisations (AMO) are tasked by the CAMOs to perform the necessary maintenance resulting from the Aircraft Maintenance Programme (AMP) or from defect identification. Reporting information from AMO to CAMO may be essential in the management of repetitive defects. Aircraft Operators and flight crews operate the aircraft and are exposed to defects. The flight crew is expected to report them through the aircraft technical log to inform the CAMO. On the other hand, the CAMO should ensure that the flight crew has all information necessary to perform the flight, which may include informing the flight crew of specific defects that could occur in a repetitive manner.

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Design Approval Holders (DAH) are responsible for the design of the aircraft. Once informed by the CAMO, they should support the investigation with a view to solve the issue and/ or propose mitigating actions (ref. section 8 on reporting among organisations of AMC 20-8A on occurrence reporting). The current EU regulatory materials identify the ‘rectification of any defect or damage affecting safe operation’ as one of the continuing airworthiness tasks, refer to Regulation (EU) No 1321/2014 Annex I (Part-M) Subpart C (continuing airworthiness) M.A.301 on continuing airworthiness tasks. Therefore, continuing airworthiness management organisations are expected to implement an effective defect control system to ensure that all defects affecting the safe operation of the aircraft are either rectified or deferred in accordance with minimum equipment list (MEL) or configuration deviation list (CDL). However, sometimes the rectification action taken may not necessarily resolve the defect in the first attempt and the same or similar defect may occur during the subsequent days and flights. In addition to the above requirement, the EU regulatory materials also require the CAMOs to implement a reliability programme to monitor the effectiveness of the aircraft maintenance programme. Such a reliability programme considers wide range of perspectives and the analysis of different types of data including the evaluation of repetitive defects, refer to Regulation (EU) No 1321/2014 Annex I (Part-M) Appendix I to AMC M.A.302 and AMC M.B.301(b) on the content of the maintenance programme. Some CAMOs have performance metrics related to repetitive defects as part of their reliability programme to demonstrate that repetitive defects are controlled and managed proactively, e.g., ‘last three-/ six-/ 12- month trend’, ‘top repetitive defects per ATA chapter’, ‘repetitive defects on critical systems’. Nevertheless, repetitive defects and potential consequences thereof on flight safety cannot be solely mitigated by relying on the reliability programme which requires taking corrective actions when adverse trends are identified. CAMOs must also identify and monitor repetitive defects on a daily basis so that they can be resolved without waiting for the next reliability report to be produced. It is important to note that the scope of this safety issue specifically focuses on identification, monitoring and resolution of repetitive defects on a daily basis.

1.3 Who is affected?

The key stakeholders affected by this safety issue are the operators, the continuing airworthiness management organisations, the approved maintenance organisations and the design approval holders.

1.4 Assessment methodology

A working group was established to conduct an in-depth assessment of this safety issue, consisting of EASA, International Federation of Airworthiness (IFA), Avioscribe, Airbus, EasyJet, Luxair, Wizz Air, Cargolux Airlines, Pegasus Airlines, KLM. The representatives contributed to the assessment by reviewing instrumental accident and serious incident reports, responding to a ‘Delphi Study’ about key questions on the management of repetitive defects, sharing their views during several online meetings, as well as reviewing the final draft of this document. The safety issue assessment was approached through the collection of safety intelligence (section 1.5), that combined multiple sources of data ranging from occurrence data to industry stakeholders’ practices and experience. The safety intelligence part of the assessment is reflected in the hereafter listed activities, from a) to c). The collected safety intelligence was then fed into the risk assessment part (section 1.6) to:

− define the most significant scenario to address inadequate management of repetitive defects,

− identify causes and contributing factors,

− assess the barriers (incl. existence and effectiveness), and

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− propose actions in accordance, to mitigate the risk.

This second part of the safety issue assessment is reflected in the hereafter listed activity d).

Type of activities Objective

a) Review of literature − Review of regulations to identify differences in some of the comparable ICAO member states (section 1.5.1 and APPENDIX A - Regulatory materials review).

− Review of accidents/ serious incidents investigation reports to better understand how repetitive defects played a contributing role (section 1.5.2 and SIA APPENDIX B - Accidents and serious incidents investigation reports review).

b) Analysis of European Central Repository data

− Review of relevant occurrences to identify any potential trends (section 1.5.3 and SIA APPENDIX C - Repetitive defects ECR dashboard (dated 20.09.2023)).

c) Collection of data from industry stakeholders

− Delphi Study limited to the working group members (section 1.5.4 and SIA APPENDIX D - Delphi study results) to capture their views and reach a consensus on four key questions about: 1. Whether there should be a clearer guidance on the definition

of repetitive defects in EU regulatory materials. 2. Whether repetitive defects should be subject to a risk

assessment collectively conducted by CAMOs and flight operations.

3. Whether the flight crews should be notified of repetitive defects before the flight.

4. Whether repetitive defects should be sometimes considered and recorded as deferred defects based on the risk assessment.

− SenseMaker Engagement to collect data from the wider industry about their lived experiences on how they dealt with repetitive defects (section 1.5.5 and SIA APPENDIX E - SenseMaker engagement results).

d) Bow-tie development − Identify all the existing threats and barriers as well as the escalation factors (i.e., regulatory requirements and industry practices) (section 1.6 and Error! Not a valid result for table.)

1.5 Safety intelligence

1.5.1 Review of regulatory status, incl. foreign authorities One of the key activities carried out was the brief review of the international standards developed by ICAO and IATA, as well as regulatory materials (incl. guidance materials) published related to repetitive defects by different ICAO member states. The results of the review are detailed in APPENDIX A - Regulatory materials review. They clearly highlighted the following observations:

− ICAO Annex 8 Airworthiness of Aircraft and ICAO Doc 9760 Airworthiness Manual: management of repetitive defects vaguely referred to in the ICAO Doc 9760 only.

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− IATA IOSA Standards and Recommended Practices (ISAPRs): Operators are required to have a defect recording and control including the management of repetitive defects. While the communication of repetitive defects to flight crew was required in previous versions of the IOSA standards manual (ISM), it was removed in the Edition 6 of the ISM published in 2012.

− TCCA maintenance related regulations: Regulatory requirements published by Transport Canada include the most prescriptive definition of recurring defects (i.e., three occurrences in 15 flights) and the most restrictive requirements about how they should be treated/ managed (i.e., removing the aircraft from service to investigate into the root cause of the defect)

− FAA maintenance related regulations: FAA website was searched to specifically focusing on Part 43 on maintenance, preventive maintenance, rebuilding, and alteration; Part 121 on operating requirements: domestic, flag, and supplemental operations; Part 145 on repair stations; any of the phrases such as ‘repetitive defects’, ‘recurring defects’, ‘repeating defects’ was however not found in any of the Federal Aviation Regulations. FAA AC 120-17B on reliability program methods/ standards for determining time limitations refers to the evaluation of repetitive defects as an example of analytical techniques and tools for root cause analysis of variations from performance standard.

− European continuing airworthiness regulation, reg. (EU) 1321/ 2014: While there are no published specific criteria in EU regulations or guidance material about what constitutes a ‘repetitive defect’, the regulation requires all operators to establish an effective defect control system including the management of repetitive defects.

1.5.2 Review of accidents and serious incidents investigation reports Accidents and serious incidents investigation reports, where repetitive defects and management thereof were identified as contributing factors, were selected for review by the working group members. The query in the European Central Repository of Safety Recommendations (SRIS2) did not provide any conclusive evidence, therefore the hereafter ten (10) accidents and serious incidents were collectively identified by the working group members based on their knowledge and sensitivity to the subject safety issue. The safety recommendations related to the management of repetitive defects are hereafter extracted from the investigation reports. Note however that the complete review of each investigation report is detailed in SIA APPENDIX B - Accidents and serious incidents investigation reports review, and records key elements in addition to the safety recommendations. For the fatal accidents, it was felt that safety recommendations fell short of addressing key issues related to the management of repetitive defects (e.g., Boeing 737-500, PK-CLC, PT Sriwijaya Air, Indonesia, 09 January 2021). For each accident/ serious incident, the following elements were documented in the appendix, when applicable:

− event summary,

− key elements of the report related to the management of repetitive defects,

− safety gap analysis towards the identification of repetitive defects, the notification/ communication of repetitive defects, the repetitive defects as hazards to flight safety, and the resolution of the repetitive defects,

− proposed mitigating actions for the identified safety gaps,

− already existing mitigating action that may need enhancement. Hereafter is the list of the accidents and serious incidents reviewed within the frame of this SIA, along with the safety recommendations related to repetitive defects. For a deeper understanding of the key elements of these accidents and serious incidents that contributed to the shaping of the risk assessment in section 1.6, the reader is strongly invited to refer to the SIA APPENDIX B - Accidents and serious incidents investigation reports review.

− Airbus A319, G-EZAC, easyJet, France, 15 November 2006

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Generator Control Units repeatedly rejected from service due to repetition of the same intermittent fault, serious incident, commercial air transport of passengers, no fatalities/ no injuries. Safety recommendation 2008-088: It is recommended that Hamilton Sundstrand modifies its repair and overhaul procedures as necessary, to ensure that a unit with an excessive service rejection rate or a recurrent fault is not repeatedly released back to service. Safety recommendation 2008-089: It is recommended that the EASA and the FAA review their measures for monitoring and approving component repair organisations to ensure they have systems in place to identify units with an excessive service rejection rate of recurrent faults.

− Boeing 737-800, TC-JGE, Turkish Airlines, Netherlands, 25 February 2009

Repetitive malfunctions of the radio altimeter, aircraft crashed during approach near Amsterdam Schiphol airport, Netherlands, commercial air transport of passengers, with 9 fatalities and 120 injuries. Safety recommendation 6: FAA, EASA and DGCA should make (renewed) efforts to make airlines aware of the importance of reporting and ensure that reporting procedures are adhered to. Safety recommendation 7: Boeing should make (renewed) efforts to ensure that all airlines operating Boeing aircraft are aware of the importance of reporting. Safety recommendation 8: Turkish Airlines should ensure that its pilots and maintenance technicians are aware of the importance of reporting.

− Airbus A320, PK-AXC, Indonesia Air Asia, Indonesia, 28 December 2014

Repetitive defects of the rudder travel limiter units, aircraft destroyed when it impacted the water of the Java Sea between Surabaya and Singapore, Indonesia, commercial air transport of passengers, with 162 fatalities. Safety recommendation 3: The KNKT recommends that the Directorate General Civil Aviation ensures that air operator maintenance system has the ability to detect and address all repetitive faults appropriately.

− Boeing 737-800, CN-ROJ, Royal Air Maroc, France, 30 December 2016

Repetitive malfunctions of the radio altimeter, serious incident, commercial air transport of passenger, no fatalities/ no injuries. Safety recommendation FRAN 2021-015: Systematic reporting of the faults and anomalies encountered by the flight crews is necessary for the maintenance personnel to correct the problems or in case of an intermittent fault, to monitor their evolution, as specified by the manufacturer’s procedures. Consequently, the BEA recommends that, whereas the non-systematic reporting of technical malfunctions by the crews does not facilitate the identification and processing of intermittent faults; Royal Air Maroc implement the necessary provisions in order that the technical malfunctions observed in flight are systematically reported in the documents provided for this purpose. Safety recommendation FRAN 2021-026: Boeing has asked operators to implement a policy for processing intermittent faults, with these faults being specifically monitored on several consecutive flights. It is possible to access the faults recorded by the main computers through the CDU, after a flight, even if they are no longer active on the ground. Consequently, the BEA recommends that, whereas Boeing lets the operator choose the strategy for resolving intermittent faults; whereas the persistence of intermittent faults which contributed to this serious incident; Royal Air Maroc reinforce its policy with respect to the processing of intermittent faults.

− Boeing 737-800, F-GZHO, Transavia, France, 08 February 2018

Repetitive defects of the AoA sensor, incidents on two consecutive flights (one ferry flight, followed by one commercial air transport with passengers), dysfunction of AoA sensor indicated by alerts during take-off, and additional turn-around for the occurrence in France.

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− Airbus A320, ES-SAN, Smartlynx Airlines, Estonia, 28 February 2018

Repeated faults of the ELAC computers, nine ELAC resets performed in flight, accident, training flight, no fatalities/ no injuries. As a result of this accident, Airbus decided to totally forbid ELAC reset following a F/CTL ELAC 1(2) PITCH FAULT ECAM alert in flight and to restrict the number of ELAC reset to one if this alert triggers on ground with additional actions to ensure that the reset has been successful.

− Boeing 737-8 (MAX), PK-LQP, PT. Lion Mentari Airlines, Indonesia, 29 October 2018

Repetitive defects of the AoA sensor, aircraft crashed into the sea shortly after take-off from Jakarta- Soekarno-Hatta International Airport, Indonesia, commercial air transport of passengers, with 189 fatalities. Safety recommendation 04.O-2018-35.8: The OMF [Onboard Maintenance Function] has the history page which contains record of the aircraft problems which can be utilized as a source for aircraft problem monitoring. The BAT [Batam Aero Technic] has not utilized the OMF information as the source of aircraft problem monitoring. Therefore, KNKT recommends that Batam Aero Technic establish policy and procedure of handling OMF. Safety recommendation 04.O-2018-35.10: After Xtra Aerospace repair of the accident AOA sensor in November of 2017, the sensor was installed on the PK-LQP aircraft on left side position during the maintenance activity in Denpasar on 28 October 2018. On the subsequent flight, a 21-degree difference between left and right AOA sensors was recorded on the DFDR, commencing shortly after the takeoff roll was initiated. This immediate 21- degree delta indicated that the AOA sensor was most likely improperly calibrated at Xtra. As noted, utilization of the Peak Model SRI-201B API by Xtra Aerospace for the test and calibration of the 0861FL1 AOA sensor should have required a written procedure to specify the proper position of the REL/ABS switch. Therefore, KNKT recommends emphasizing the implementation of a company manual including equivalency assessment, training and written procedure, to ensure component being repaired are properly maintained. Safety recommendation 04.R-2018-35.22: The absence of equivalency assessment required by Xtra Aerospace procedure and unavailability of procedure was not detected by the FAA. This indicated inadequacy of the FAA oversight. Therefore, KNKT recommends that the FAA improves the oversight to Approved Maintenance Organization (AMO) to ensure the processes within the AMO are conducted in accordance with the requirements.

− Airbus A319, N521NK, Spirit Airlines, United States, 15 February 2020

Repetitive defects of the engine integrated drive generator (IDG), ram air turbine (RAT) automatic extension upon dual loss of electrical power while on approach to the Sacramento International Airport, Sacramento, California, commercial air transport of passengers, no fatalities/ no injuries. As a result of this incident, Airbus has improved their troubleshooting manual (TSM) by incorporating steps to direct maintenance towards a direct extraction of the post flight report (PFR) and troubleshooting data (TSD) from the GCUs.

− Airbus A321, G-POWN, Titan Airways, United Kingdom, 26 February 2020

Repetitive malfunctions of the engines, incident, commercial air transport of passengers, no fatalities/ no injuries. The manufacturer’s recommended method of searching the troubleshooting manual was not used to find the engine stall applicable procedure. As a result of this serious incident, a safety and compliance notice was issued to disseminate the manufacturer’s training material on using the AirN@v TSM. This was also added to their Airbus engineer type training courses and equivalent material for airnavx.

− Boeing 737-500, PK-CLC, PT Sriwijaya Air, Indonesia, 09 January 2021

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Repetitive defects of the autothrottle, aircraft crashed into the sea, shortly after departure from Jakarta-Soekarno-Hatta International Airport, Indonesia, commercial air transport of passengers, with 62 fatalities. Safety recommendation 04.O-2021-01.05: The samples of the Sriwijaya Air hazard report in the period of 2020 showed that majority of the hazard were reported by ground personnel. Few hazards were reported by pilots and maintenance personnel and there was no hazard report by dispatchers. This unbalance composition of the hazard reporters indicated that hazard reporting program has not been emphasized to all employees which might result in hazards not being identified and mitigated. Therefore, KNKT recommends Sriwijaya Air to emphasize the hazard reporting program to all employees to encourage hazard reporting.

From the reports, the following key issues were identified:

− Components released back to service despite excessive rejection rate or recurrent faults (rogue1 units),

− Either lack of or poor reporting of defects in the aircraft technical logbook so that repetitive defects are not identified as such;

− Incorrect or incomplete troubleshooting, clearing the flight deck effects or aircraft symptoms but not solving the root cause;

− Normalisation of aircraft system resets, exacerbating the above items of concern; − Insufficient CAMO awareness and control of every aircraft repetitive defects; − Repetitive defects and management thereof mostly addressed as a component/ equipment

reliability issue only, with no hazard assessment on flight safety.

1.5.3 Review of occurrences from the European Central Repository

1.5.3.1 Aggregated overview

The European Central Repository (ECR) was queried on the 20th of September 2023. The initial dataset encompassed all occurrences (i.e., accidents, serious incidents, and incidents), for the period from 2017 onwards, where the value of the occurrence attribute ‘narrative text’ was containing the words ‘recurrent defect’ or ‘repetitive defect’ or ‘recurrent fault’ or ‘repetitive fault’ or ‘recurrent failure’ or ‘repetitive failure’. The dataset was further refined to remove duplicates, and occurrences found not applicable. The full aggregated overview is provided in SIA APPENDIX C - Repetitive defects ECR dashboard (dated 20.09.2023). During the period 2017-2023, 110 records of occurrences of repetitive defects were reported in the ECR. While 2023 is not complete, the yearly number of occurrence records of repetitive defects steadily increased over 2020-2023, with a higher number in 2022 (20) and 2023 (23) than in the pre-pandemic year 2019 (16). Note that Europe air traffic numbers in 2022 had returned to 83% of the 2019 traffic levels. By summer 2023, traffic had already rebounded to 93% of 2019 levels.

1 A rogue unit is a single serialized line replaceable unit (LRU) which has demonstrated a history of identical system faults which may or may not result in an exceedance of an operator’s defined number of repetitive unscheduled removals within an associated short service life (FAA AC 120-17B).

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Figure 1 - Number of occurrence reports per year

The main affected aircraft systems are flight control system, autoflight system, air conditioning and pressurisation system, fuel system, landing gear system, and navigation system.

Figure 2 - Number of occurrence reports per ATA chapter

Three out of five occurrence records of repetitive defects (70) are classed as ‘incident’. 17 occurrence records are classed as ‘occurrence without safety effect’, although four of them adversely affecting the flight control system.

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Figure 3 - Number of occurrence reports and distribution per occurrence class

1.5.3.2 Narrative text review

From the following five occurrence reports that are further detailed hereafter:

− three reports were selected from the refined dataset (2017 onwards), which aggregated overview is presented in the previous section;

− two were selected out of the refined dataset, they occurred in 2012 and 2016, but they are retained here because of the interest raised by their narrative.

These reports demonstrate not only potentially high-risk events as a result of repetitive defects, but also challenges faced by the flight deck and engineering crews during the identification, investigation and resolution of repetitive defects.

Report Summary of the investigation

01 OC-0000000002923694/ Incident/ GENOCC - RECURRENT PIREPS TCAS TRAFFIC NOT SHOWING CORRECTLY

Aircraft has experienced a recurrent pilot reports #TCAS TRAFFIC NOT SHOWING CORRECTLY#: As per technical logbook entries, it seems the TCAS does not detect traffic beyond 2700ft.

T/S as per TSM Task 34-72-00-810-832-A - Incorrect Location of the TCAS Intruders on the NDs carried out with following outcomes:

− 05 Nov. TCAS Bottom Antenna replaced − 01 Dec. TCAS replaced − 04 Dec. TCAS Top Antenna replaced − 09 Dec. On arrival from CCJ pilot reported ‘‘TCAS below scan is not showing even

with mode selector on below’

Short Term Action:

TCAS System test as per AMM34-72-00 reported ok. ATC/ TCAS control panel replaced due to recurrent defect. Post replacement Test ok.

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Report Summary of the investigation

02 OC-0000000001944520/ Incident/ Aileron control restriction fault isolation discrepancy

The aircraft had a repetitive defect related to control wheel restrictions. This commenced on the 27th of October 2019 and has occurred 4 further times, the most recent event being on the 11th of February 2020.

Following the most recent event TLP2, the aircraft was declared serviceable and offered for an Elective Check Flight, however before the Check Flight Paperwork was signed, the Technical Pilots contacted Reliability / Systems for further comment.

A timeline of troubleshooting and a review of troubleshooting was performed, and following review, it was believed that all possible troubleshooting had been performed, particularly in light of the most recent finding of water on the aileron input quadrant bearings. It was mutually agreed that it would be beneficial to have the recorded control wheel forces, to serve as a benchmark, and as such an LMWR3 was raised to perform an Aileron Control Wheel Test iaw AMM 27-11-00-700-805 and record the values. Note: FIM 27-11 Task 813 Step G, Para 4 includes Control Wheel Force Checks, which was cited as being completed on WO.

During the completion of LMWR (AMM 27-11-00-700-805) on WO, it was noted that several of the values exceeded the limits. As such the aircraft was declared AOG and further troubleshooting was performed which resulted in the A System Flight Control Module Package Assembly.

During review of previous maintenance actions carried out on the Captains Control Column, it could not be demonstrated that previous maintenance carried out on the captains control column was completed in accordance with appropriate maintenance data.

The captains control column and control wheel assembly was replaced and routed to MRO for further investigation and Overhaul.

03 OC-0000000001613443/ Incident/ Rejected take-off due red flag on P1 airspeed indicator (ASI) at 80kts

ASR/2182 07/01/2016:

During the take-off roll at 80 kts it was noticed the P1 ASI was displaying a red flag and the red ‘SPD’ warning was displayed on the EFIS screen. The Take off was rejected at 85kts with minimal braking. The aircraft was taxied off the runway where the fault self- cleared. Abnormal checklists and LMC were consulted and after Brake Cooling a second departure was carried out with no further incident.

ASR/2226 18/01/2016:

Take off rejected at approximately 70 kts due to speed flag on left pilot ASI and EADI. Aircraft back to stand and Techlog entry made.

ASR/2276 21/01/2016:

2 Technical Log Page (TLP) 3 Line Maintenance Work Request (LMWR)

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Report Summary of the investigation

High Speed RTO detected by FDM- No ASR filed by Commander but it is annotated in log that Ops and LMC were made aware and the reported issue was fluctuating airspeed.

On both the 18th January 2016 and the 21st January 2016 the fault reoccurred causing a further two rejected take-offs.

The warning could no longer be considered to be spurious and further engineering investigation was carried out. It was observed that all three faults happened on the first flight of the day. Following the second rejected take off on 18th January, the engineers suspected the indication was due to a problem with the pitot static tube. Water drains were checked and operational test were completed that day. As well as this a pitot static check was completed with the aircraft at speed 180kts. Engineers were unable to reproduce fault.

Fault diagnosis carried out by engineers and subsequently the decision was made to replace the P1 Air Speed Indicator (ASI). A fault with this system could have caused the indication described in both ASR/2182 and ASR/2226 as well as the fluctuating speed indication described in asr/2276 and in TLP 030445-4/02.

On the 21st of Jan 2016 the Air Speed Indicator (ASI) P1 was replaced. The ASI P1 removed in this case, P/N 622-6728-011, was fitted to A/C on the 01 Jun 2010. This component completed 7401 unit hours and 10080 landings. A Repetitive Defect Investigation was raised on the 21st of Jan 2016 in order to track this fault further and any future reoccurrence. Tech log monitored and there has been no further fault reoccurrence since the ASI replacement on the 21st of January.

04 OC-0000000002252963/ Incident/ Dual autopilot failure

FO was PF for departure phase and Capt. took control for the remainder of the flight. On swapping the autopilots from B to A, autopilot A did engage and then about 5 seconds later disengaged. All switches and CB's were checked and we completed QRH checklist for Autopilot failure. Autopilot B could not be engaged either. Informed ATC and stopped climb at FL270 and reviewed situation. Contacted Ops and Maintrol on VHF Box 2 and we all agreed that we could continue to Salzburg. Engineering cover met us in Salzburg. CWS was used to aid flight. Engineers could not fix problem and in fact further issues developed in that the FO's flight director was now inoperative and Mach Trim Fail and Speed Trim Fail were now operating single channel only. Capt. flew aircraft back to UK base for maintenance. No further faults developed.

Root Cause information is stored in the safety system however is restricted. Corrective actions: DFCS MCP replaced. Further testing to be carried out. Instruction sent to *** from tech services to monitor autopilot issue due to long history of defects. **** raised for land verify test to be c/o before next flight sector 24/02/18, test c/o satis Autopilot failure occurred 24/02/18, trouble shooting and wiring checks carried out, confirmed pressure switch fault, component replaced. As per safety request response received from Reliability, the troubleshooting found that the repetitive defect was linked to the Autopilot Elevator Pressure Switch. Since its replacement the aircraft has not suffered any further defects. The Flight Control Computer was confirmed to be NFF by *****. Company have a policy where PN: ***** Pressure switches are not repaired and replaced with new units only.

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Report Summary of the investigation

05 OC-0000000002725698/ Incident/ Spoiler elevator computer (SEC) failed on touchdown

On Tech Log review, it was discovered that SEC1 had failed at least nine times on preceding days, each time it had been reset on ground. Reporter is concerned that multiple resets have been allowed on critical flight control hardware.

NAA Closure: The unit had been installed on the 24 Nov as part of a scheduled modification program. A couple of days after installation this unit became faulty and post flight reports showed 'F/CTL SEC 1' faults with six defect entries leading up to the day of the event.

The investigation showed that although these defects had been reported, the incorrect ATA sub-chapter codes had been recorded in three of the events (27-96-00 & 27-00-00 instead of 27-94-00) thus rendering the defect outside the parameters of the repetitive defect monitoring system. On the 03 Dec the repeat resets were noticed by Engineering as part of their daily PIREP monitoring checks.

Technical Services were informed and carried out a history check of all recently installed SEC units and their investigation revealed that the SEC had a previous fault history. Therefore, as a precaution this unit was removed and sent to the vendor for investigation. The SEC units have a known reliability issue, and a modification programme is currently on-going. A Tech Log page defect review was carried out and this revealed a repetitive SEC 2 faults. After two successful resets this defect was captured on the third event and a defect raised for rectification. SEC 1 and SEC 3 interchanged and SEC 3 subsequently replaced. A Quality Notice was issued regarding the need for correct recording of ATA chapters and sub-chapters for maintenance entries.

1.5.4 Conclusions of the Delphi study Considering the findings and recommendations established by the accidents and serious incidents investigation bodies, and the results of the regulatory material review, four key questions were discussed by the working group members in a two-round Delphi Study4. These are:

− Q1. Do you think there should be a definition of repetitive defect in the regulations/ guidance material published by the regulators?

− Q2. Do you think repetitive defects should be subject to ‘risk assessment’ collectively conducted by flight operations and CAMO?

− Q3. Do you think the flight crews should be notified of repetitive defects before the flight so that they can consider the potential operational risks?

− Q4. Do you think repetitive defects should be recorded as ‘deferred defects’ based on the risk assessment conducted collectively by CAMO and flight ops teams?

4 Delphi is a scientific method to organize and structure an expert discussion aiming to generate insights on controversial topics with limited information. (Source: https://www.sciencedirect.com/science/article/pii/S2215016121001941)

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During the first round, working group members were asked to respond to the above ‘closed questions’ but they were also asked to clearly articulate their reasoning behind their choice. Unfortunately, consensus was not achieved in any of the questions. In the second round, the members were asked to review all the responses and then share their thoughts and views about the same questions. Unfortunately, not only the number of responses were lower than first round, but again no clear agreement on these key questions. Nevertheless, it would be fair to conclude the following key points.

− Most of the group members believe that some clarification should be included in the European guidance material about the identification of repetitive defects. A prescriptive definition using specific numbers (e.g., three occurrences in ten days or five occurrences in 20 flights) may however not always be helpful to capture all repetitive defects that need to be controlled to mitigate all associated flight safety risks.

− Although it may not be possible for all repetitive defects, the second-round responses recognised that collectively conducting risks assessments, particularly for those systems contributing to critical functions or adversely affecting handling qualities and performances, would be beneficial.

− The communication of repetitive defects to flight crew was the most controversial topic which group members expressed diverse views. While many argued that trying to notify all repetitive defects would overload the flight crew and potentially create unnecessary confusion, there was also reasonable agreement for the need to have certain repetitive defects to be visible to flight crew, when critically important for situational awareness.

− There was finally reasonable agreement that certain repetitive defects based on risk assessments could/ should be recorded as deferred defects so that they are visible to flight crew and for their potential impact on flight planning (e.g., fuel planning or ETOPS/ EDTO flights etc.)

The details of all the responses of both rounds can be found SIA APPENDIX D - Delphi study results.

1.5.5 Conclusions of the SenseMaker engagement In addition to the Delphi study, a SenseMaker5 engagement was designed to capture industry professionals’ ‘lived experiences’ about managing repetitive defects. The purpose of this survey was to better understand the specific scenarios how operators manage and control repetitive defects or perhaps also to capture scenarios that presented significant threat to flight safety. Even though this survey was promoted by the EASA Safety Promotion team and the working group members, the participation was very low and only 34 responses were received. Nevertheless, the responses provided some interesting cases where aircraft with repetitive defects impacting on flight safety were allowed to continue in revenue service. At the other end of the spectrum, some operators clearly treat repetitive defects as ‘deferred defects’. Two examples of shared scenarios are included in Figure 4; however, the entire dataset can be found in SIA APPENDIX E - SenseMaker engagement results.

5 SenseMaker® is an online platform and an original distributed ethnographic approach to sense-making which enables the participants to share their ‘lived experiences’ and

subsequently by answering unique questions, it enables self-signification – allowing respondents to give meaning to their own experiences. (Source:

https://thecynefin.co/about-sensemaker/)

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Figure 4 - Examples of shared scenarios on the management of repetitive defects considering competing goals

1.6 Risk assessment

2 Using the safety intelligence collected through the multiple activities described in section 1.5, a bowtie diagram was developed to support the assessment. The full diagram is to be found in

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SIA APPENDIX F - Bowtie diagram.

Figure 5 - Top event: Aircraft with a repetitive defect present

The diagram is organised around the top event ‘aircraft with a repetitive defect present’. The threats and prevention barriers mainly address the identification of repetitive defects, while the consequences and mitigation barriers are about controlling the risk associated with dispatching an aircraft with repetitive defects.

Figure 6 - Threat 1: Ineffective troubleshooting

Failure/ fault troubleshooting is one key element in the identification of repetitive defects. Ineffective troubleshooting addresses here incorrect or incomplete troubleshooting, as well as unsuccessful

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troubleshooting, e.g., where the fault is eventually not confirmed/ not found having exhausted the likely root causes. The safety intelligence collected, particularly within the review of the accidents and serious incidents reports, shows cases of incomplete or non-adherence to the aircraft manufacturer isolation/ troubleshooting manual procedures, mainly driven by the normalisation of failure/ fault clearance:

− aircraft systems are reset cycling circuit breakers to clear the fault messages instead of proper investigation of the root cause, or

− troubleshooting procedures are stopped after recurrent and successful BITE tests whereas the root remains unconfirmed.

A fault not confirmed/ not found may not mean that the aircraft is airworthy, it may just mean that the fault appears under specific conditions, especially if it had already happened. A proper system knowledge and understanding of the defect interpretation, together with a historical fault check, is therefore primordial. Airbus developed safety promotion materials on intermittent repetitive failures and the use of system reset (ref. section 2.1). Airbus materials may however not reach all European operators, particularly the ones not operating Airbus aeroplanes. Plus, the philosophy of system resets may be quite different from one product to the other, or from one manufacturer to the other. It is therefore recommended to develop additional safety promotion materials at European level, that would be product-/ manufacturer-agnostic. It should equally encourage aeroplane manufacturers to develop specific materials for their operators. Implementation of the management system is required per 145.A.200 ‘Management system’. The normalisation of fault/ failure clearance is therefore proposed to be identified in the hazard risk register of the line maintenance organisations. The fact that the fault is not present on ground does not mean that the failure code cannot be found by interrogating the aircraft systems/ units. When all troubleshooting is performed in accordance with the approved manuals and no root cause is identified, a maintenance check flight may be requested to further assist the fault isolation as described GM M.A.301(i)(b)(3). The maintenance check flight is performed here in accordance with the standard operating procedures. Finally reporting of occurrences among organisations (i.e., not only reporting to competent authorities) is paramount in the management of repetitive defects and should be improved. It is therefore recommended to stress out the consideration of reporting amongst organisations to address ineffective troubleshooting (e.g., misleading, incorrect, or insufficient applicable maintenance data or procedures)(ref. section 8 on reporting among organisations of AMC 20-8A on occurrence reporting, ORO.GEN.160 occurrence reporting, M.A.202 occurrence reporting, and 21.A.3A reporting system).

Figure 7 - Threat 2: Fault/ failure not reported or incompletely reported in the aircraft technical logbook

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An incomplete or lack of fault/ failure reporting in the aircraft technical logbook directly affects the identification of the repetitive defects. Like the previous threat focused on ineffective troubleshooting, the safety intelligence collected, particularly within the review of the accidents and serious incidents reports, shows cases of incomplete or non-adherence to the aircraft operating limitations and procedures, mainly driven by the normalisation of aircraft system resets by the flight crew on ground or in flight. The recommendation on the development of safety materials similar to the existing Airbus intermittent repetitive failures and use of system reset is therefore equally valid here. As described in the threat related to ineffective troubleshooting, resetting systems may only clear the indication, while the failure remains latent. The failure may degrade over time or may escalate to serious consequences when combined with other system failures during the next flights. Repetitive resets of systems may actually indicate repetitive failures and should therefore be recorded in the aircraft technical logbook. A couple of accidents and serious incidents investigation reports show that post flight reports and associated failure/ fault messages/ codes were not sufficiently considered, resulting in failures/ faults not reported, or incompletely reported so that the line maintenance engineer would entry the troubleshooting manual with incorrect input. When the technology for an aircraft health monitoring system exists and data are produced, these data are not quite used today. Experience outlines also that the pilot may not report all the flight deck effects or aircraft behaviours experienced during the flight. Automation or semi-automation in the reporting of failures and faults based on monitored systems and computers would improve the completeness and correctness of the aircraft technical logbook, and actively support the next steps of the troubleshooting.

Figure 8 - Threat 3: No fault/ failure found units released back to service

Components released back to service despite excessive rejection rate or recurrent faults is a threat identified in the investigation report of one incident only. Oversight of component repair organisation should ensure organisations have a system in place to identify units/ components with excessive rejection rate or recurrent faults. There is no additional recommendation driven by this safety issue assessment.

Figure 9 - Threat 4: Ineffective CAMO defect control system

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As per AMC M.A.301(b) Continuing airworthiness tasks, the management of repetitive defects is part of the CAMO defect control system. Managing repetitive defects is a function of both the reliability programme within CAMOs (i.e., monthly/ quarterly reliability reports/ meetings) and the ‘maintenance/ operations control centres’ which are responsible for monitoring repetitive defects on a daily basis. Regulatory requirements in some ICAO members states and some organisations in the industry use a clear definition of repetitive defects which includes a specific criterion (e.g., any defect occurring three times in 10 days or five times during 15 flights, etc.) However, use of such specific criteria may not always be helpful to identify and assess all the safety risks impacting on flight safety. Therefore, providing some guidance on which defects should be classified as repetitive but more importantly using engineering judgement is vital for the CAMOs to capture all repetitive defects which may potentially pose significant flight safety risks. Subsequently they can consider previous troubleshooting and rectification attempts and determine next actions to be taken, highlighting here the importance of communicating with the maintenance organisations to avoid duplication of unsuccessful attempts at rectification. Having no clear guidance in regulatory documents on which defects operators should classify as repetitive defects sometimes may result in organisations including a definition with specific criteria in their procedures. For operators dealing with large number of flights every day, some level of automation can be introduced based on an algorithm to capture the repetitive defects which only meets the criteria defined in the ground monitoring system; however, some other repetitive defects which can still pose flight safety risks, may be potentially excluded/ missed (e.g., defects not monitored by aircraft systems), and not dealt with as required. Therefore, applying both specific criteria-based approach and using engineering judgement is crucially important. Repetitive defects can be difficult to identify and rectify, and root causes thereof have the potential to remain latent over long periods of time. They may affect the safe operation of aircraft, particularly if combined with other defects, or when they occur on highly integrated systems, potentially impacting on automation and/ or on flight crew workload. While there is no intent to request for a strict definition of repetitive defects in the European continuing airworthiness regulation, it is recommended to provide guidance materials to the CAMOs, ensuring the repetitive defects and associated risks are well understood and addressed in their procedures. Implementation of the management system is required per CAMO.A.200 ‘Management system’. Repetitive defects are therefore proposed to be identified as a hazard in the risk register of the CAMOs. In addition, at the level of the European competent authorities, it is recommended to introduce the management of repetitive defects as an item of emphasis in the CAMO oversight inspection program. As highlighted in the previous threats, reporting among organisations is to be considered, here particularly the CAMO reporting to the aircraft manufacturer. Finally, as needed, the CAMO may request a maintenance check flight to verify successful defect rectification after maintenance as described GM M.A.301(i)(b)(2). The maintenance check flight is performed here in accordance with the standard operating procedures.

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Figure 10 - Consequences: Mitigations adapted to the risk classification when dispatching the aircraft with repetitive defects

Once identified, repetitive defects are mainly regarded as an equipment/ component technical issue with an adverse reliability trend, rather than a hazard to flight safety. As particularly highlighted by the Turkish Airlines fatal accident in 2009, there is a need for a holistic approach to risk management within an airline i.e., both CAMOs and flight operations collectively risk assessing repetitive defects, and triggering mitigating actions commensurate with the risk classification. CAMOs have to deal with repetitive defects every day, therefore, carrying out risk assessments for every single repetitive defect would not be possible for any organisation. Nevertheless, as clearly indicated by the reviewed accident investigation reports, considering repetitive defects only as a reliability trend and not viewing them through the lens of flight safety risks can potentially create huge challenges for the flight crew. A typical example was the reliability issues impacting on the autothrottle system resulting in the flight crew continuing reliance on automation during approach and unfortunately a controlled flight into terrain accident. Repetitive defects on essential or critical systems particularly impacting on automation not being visible to flight crew would limit their ability to deal with the consequences of such defects in high workload situations during flight (e.g., the unreliable radio altimeter reading, resulting in autothrottle to command retard during final approach and ultimately causing the aircraft to stall).

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Without proper risk assessment, a high-risk repetitive defect (e.g., a radio altimeter showing incorrect reading and feeding information to autothrottle) may not be seen as a threat to flight safety but just a reliability issue. Not recording such repetitive defects as ‘deferred defects’ enables the organisation to continue flying the aircraft in revenue service. Furthermore, it also makes such defects not clearly visible to the flight crew and limits their ability to be situationally aware when such defects reoccur during critical phases of the flight.

2.1 Existing actions

There are no specific actions related to inadequate management of repetitive defects included in the current EPAS 2023-2026. Safety promotion materials were published by Airbus and EASA in the past couple of years:

− Airbus safety first magazine, System reset: use with caution, July 2021

https://safetyfirst.airbus.com/system-reset-use-with-caution/

− Airbus FAST magazine, Intermittent repetitive failure (find it, fix it!), December 2022

https://aircraft.airbus.com/en/newsroom/stories/2022-12-intermittent-repetitive-failure

− Conversation aviation magazine, System reset: use with caution, March 2023, article developed by Airbus

3 Baseline scenario – What would happen if there is no additional action?

Without additional mitigations measures, the safety risks identified in the Chapter 1 will remain.

4 Intervention objectives

The overall objectives of the EASA system are defined in Article 2 of the Basic Regulation. This proposal will contribute to the achievement of the overall objectives by addressing the issues outlined in Chapters 1 and 2.

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5 List of proposed actions

5.1 List of proposed actions with identification of EPAS action type and link to bowtie

Action number

Action title Issue Objective Action type

Bowtie diagram

1 Development of guidance material on repetitive defects

Repetitive defects mainly considered as a reliability issue

Provide clarification on repetitive defects, identification, and management thereof, not limited to reliability programme

RMT Threat 4/ consequences

2 Oversight of CAMOs and AMOs on the management of repetitive defects

Ineffective defect control system

Focus competent authorities oversight activities to ensure repetitive defects are effectively managed

MST Threat 1/ threat 4

3 Promotion of good practices on managing repetitive defects

Sharing good practices from industry and regulatory stakeholders on how repetitive defects are identified, monitored, resolved, and documented as a key safety risk, as part of their SMS.

SPT Threat 1/ threat 2/ threat 4/ consequences

5.2 Detailed definition of proposed actions

5.2.1 Development of guidance material for repetitive defects The discussions within the working group and the results of the Delphi study clearly indicated that not necessarily a very prescriptive definition such as the statements in the TCCA regulations but a guidance on how CAMOs should consider repetitive defects would be beneficial for all stakeholders, incl. identification, coordination AMO, CAMO, and aircraft manufacturer, risk assessment collectively conducted by CAMO and flight operations, etc. The guidance should highlight that repetitive defects may present hazard to flight safety and should not be solely addressed by reliability programmes.

5.2.2 Oversight of CAMOs and AMOs to ensure repetitive defects are effectively managed

The competent authorities can and should give sufficient focus on this safety issue during their oversight activities.

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Considering the recently implemented Part CAMO regulations, the hazards and risks associated with repetitive defects which may impact on flight safety should be well documented as part of CAMOs SMS. Equally the hazards and risks associated with the normalisation of failure/ fault clearance should be documented as part of AMOs SMS. Coordination between CAMOs and AMOs is paramount, and coordination procedures should address repetitive defects. Reporting amongst organisations is to be stressed out, and implementation reviewed, when addressing repetitive defects.

5.2.3 Promotion of good practices on managing repetitive defects There are many organisations which implemented robust processes to manage repetitive defects effectively. Nevertheless, the discussions within the working group and the results of the Delphi study have revealed sometimes contrasting views and practices particularly about whether flight crews should be informed about some of the repetitive defects, whether some repetitive defects should be subject to a collective risk assessment and finally, whether sometimes repetitive defects should be treated as deferred defects or not. It can be argued that the differences in opinion on these topics was due to the context and the surrounding circumstances each organisation operates. Therefore, a safety promotion task which aims to explore these differences and share good and innovative ideas would be beneficial for all the other organisations. Example of practices:

− Communicating that a fault not confirmed/ not found does not mean that the aircraft is airworthy. A proper system knowledge and understanding of the defect interpretation, together with an historical fault check, is primordial.

− Using system resets with caution. − Recording each equipment/ system reset in the aircraft technical logbook, even when seemingly or

perceived as successful. − Reporting any defect observed by the flight crew, including those that self-clear. − Adopting common wording between flight crews and maintenance engineers when recording

failures/ faults or other events in the aircraft technical logbook. − Using not only the aircraft technical logbook but also aircraft data through digital tools to monitor

and identify repetitions. − Systematic recording of any troubleshooting manual step performed with results. − Introducing automation or semi-automation in the reporting of failures and faults based on

monitored systems and computers. − Developing and implementing risk-based approach and procedures to repetitive defects. − Developing procedures coordinating the different organisations contributing to the management of

repetitive defects. − Timely sharing of information related to aircraft defects, and coordination between the competent

authorities for the different domains, e.g., the CAMO competent authority, the Part 145 competent authority and the state of registry competent authority.

5.3 Discarded actions

No discarded actions.

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6 Conclusion

The global assessment of the proposed actions can be found in the first page of the BIS report and the details are in Annexes B, C and D of the BIS report.

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7 SIA APPENDIX A - Regulatory materials review

Review of international standards, regulatory requirements, and guidance material in some of the ICAO member states:

SOURCE DOCUMENT

REFERENCE REQUIREMENT/ GUIDANCE

ICAO Annex 8 Airworthiness of Aircraft

The entire document

No mention of any of the following words/ phrases:

‘recurrent defects’, ‘repetitive defects’, ‘repeating defects’

ICAO Doc 9760 Airworthiness Manual

Part III State of Registry, Attachment A to Chapter 10 (III- 10-A-3)

CONTENT OF A MAINTENANCE ORGANIZATION’S PROCEDURES MANUAL

Annex 8, Part II, 6.3, provides that the following information be included in the manual:

a.

b.

…

m.

Notwithstanding the above requirements, consideration should be given to including the following in the procedures manual:

a) Management

b) Maintenance procedures

c) Line maintenance procedures (when applicable)

i.

ii.

iii. line maintenance control of defects and repetitive defects;

European continuing airworthiness regulation

Regulation (EU) 1321/ 2014

There is no definition of ‘repetitive defect’ in the European continuing airworthiness regulation. The CAMO is basically expected to ensure that the repetitive defects are identified, analysed, and mitigated (e.g., adjustment of the maintenance programme, decision to implement a non-mandatory service bulletin, etc.)

AMC M.A.301(b) ‘continuing airworthiness tasks’ for addressing the rectification of defect and damage affecting safe operation recommends, in case of aircraft used by licensed air carriers and of complex motor-powered aircraft, the implementation of a system in order to assess the effectiveness of the CAMO defect control system in use. This system should provide for -amongst other- repetitive incidents and defects: monitor on a continuous basis defects

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SOURCE DOCUMENT

REFERENCE REQUIREMENT/ GUIDANCE

occurring in flight and defects found during maintenance and overhaul, highlighting any that are repetitive.

Appendix I to AMC M.A.302 and AMC M.B.301(b)

‘aircraft maintenance programme’ provides detailed information on the content of an approved maintenance programme (AMP). Aircraft maintenance programmes of complex motor-powered aircraft, based upon maintenance steering group (MSG) logic or those that include condition monitored components or that do not contain overhaul time periods for all significant system components, shall include a reliability programme. The purpose of a reliability programme is to ensure that the aircraft maintenance programme tasks are effective and their periodicity is adequate. As per this appendix section 6.5.6.2, the reliability programme should involve evaluation of repetitive defects.

Appendix II to AMC1 CAMO.A.125(d)(3)

‘terms of approval and privileges of the organisation’ addresses subcontracting of continuing airworthiness management tasks. The section 2.13 ‘defect control’ specifies that where the CAMO has subcontracted the day-to-day control of technical log deferred defects, this should be specified in the contract and should be adequately described in the appropriate procedures. These procedures should include the responsibilities and actions to be taken for repetitive defects.

AMC 145.A.70(a) ‘maintenance organisation exposition’ provides the information to be included in the maintenance organisation exposition of a part-145 organisation. The exposition should include a chapter L2.3 ‘Line maintenance control of defects and repetitive defects’.

FAA maintenance regulation

FAR 43

FAR 121

No mention of any of the following words/phrases:

‘recurrent defects’, ‘repetitive defects’, ‘repeating defects’

AC 120-17B Subject: Reliability Program Methods—Standards for Determining Time Limitations, Date: 19/12/2018

The chapter 5 on analysis and recommendation refers to the evaluation of repetitive defects as an example of analytical techniques and tools for root cause analysis of variations from performance standard.

Parag. 5.1.1 Techniques and Tools. Examples of analytical techniques and tools that may be used include:

[…] Evaluation of repetitive defects, including:

− No Fault Found (NFF). NFF occurs when a system is tested after a fault is reported but the fault is not replicated during the test.

− Rogue Units. A rogue unit is a single serialized line replaceable unit (LRU) which has demonstrated a

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history of identical system faults which may or may not result in an exceedance of an operator’s defined number of repetitive unscheduled removals within an associated short service life.

− Chronic Units. A chronic unit is a single serialized LRU which has demonstrated a history of different system faults resulting in an exceedance of an operator’s defined number of repetitive unscheduled removals within an associated short service life.

− Chronic Systems/Aircraft. A chronic system or aircraft is identified by a specific aircraft serial number which has demonstrated a history of repetitive unscheduled maintenance defects within the same system/subsystem during an operator-defined period of time. […]

TCCA maintenance regulation

CAR 706.05 ‘defect recording, rectification, and control procedures’, from subpart 6 ‘aircraft maintenance requirements for air operators’ of part VII ‘commercial air services’, requires an air operator to include in its maintenance control system the procedure referred to in the commercial air service standards for detecting defects that recur and identifying these defects as recurring defects. https://tc.canada.ca/en/corporate-services/acts-regulations/list- regulations/canadian-aviation-regulations-sor-96-433

STD 726.05 ‘defect recording and control’ describes that:

− the defect recording system has to include a method to highlight defects that recur, so that they are readily identifiable by flight crews and the maintenance organization at all bases where the aircraft is operated. The air operator is responsible for identifying defects as recurring defects to maintenance personnel in order to avoid the duplication of unsuccessful attempts at rectification.

− the defect control system has to ensure that the rectification of a defect identified as a recurring defect will take into account the methodology used in previous repair attempts.

− defects are recurring defects if a failure mode is repeated three times, on a particular aircraft, within 15 flight segments of a previous repair made in respect of that failure mode.

https://tc.canada.ca/en/corporate-services/acts-regulations/list- regulations/canadian-aviation-regulations-sor-96- 433/standards/standard-726-air-operator-maintenance- canadian-aviation-regulations-cars#726_05

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REFERENCE REQUIREMENT/ GUIDANCE

STD 726.08(1)(o) ‘maintenance control manual’ requires that the maintenance control manual of an air operator shall contain a description of the defect rectification and control procedures, including the methods used to detect and report recurring defects. https://tc.canada.ca/en/corporate-services/acts-regulations/list- regulations/canadian-aviation-regulations-sor-96- 433/standards/standard-726-air-operator-maintenance- canadian-aviation-regulations-cars#726_08

TP14408 ‘TCCA guidelines:

‘maintenance control manuals’ provides explanatory narrative in section 15 ‘defect control and rectification’, along with an example for handling recurring defects: ‘A recurring defect is one that reoccurs 3 times in 15 flight segments. Once a defect has been identified as a recurring defect the Maintenance Manager will remove the aircraft from service in order to conduct an investigation into the root cause of the defect. The aircraft will remain off-line until the Maintenance Manager is satisfied that the source of the defect has been permanently fixed. The Maintenance Manager will review the last 15 flight segments in the Journey Log for any signs of a recurring defect.’ https://tc.canada.ca/en/aviation/publications/transport-canada- civil-aviation-guidelines-maintenance-control-manuals-tp- 14408/tp-14408-transport-canada-civil-aviation-guidelines- maintenance-control-manuals-1

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8 SIA APPENDIX B - Accidents and serious incidents investigation reports review

8.1 Airbus A319, G-EZAC, easyJet, 15.09.2006

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

AAIB 4/2009 France 15.09.2006 Incident Airbus A319/ G-EZAC/ easyJet

Event summary/ Key elements

Event summary: − Previous flight -2:

• Elec gen1 fault twice during flight. GCU 1 replaced tested ok but tripped again during ground run, reset, A/C released for service. − Previous flight -1:

• After 20 min in flight ELEC GEN 1 fault, GEN 1 tripped off, ECAM proc: one attempt reset, failed. Selection OFF, APU ON. Mx contacted for a later MEL possibility. − Incident flight:

• MEL applied, GEN 1 off, APU to be active throughout the flight. Entry made in aircraft TLB. When changing over, the pilots shared about the Gen 1 issue.

• In cruise Cpt PFD, ND, upper ECAM, MCDU became inoperative, AP, A/THR disconnected. No radio communication. no Transponder, ALT law, ELEC AC ESS BUS FAULT => Procedures reported followed by capt but no reconfiguration of the electrical system. GEN 1 OFF/ON no change, back OFF.

• Aircraft could only be controlled manually, performed by the FO as his displays were ok but w/o flight director.

• Restart of the APU, by the capt, had no effect on the electrical system. Crew decided that the best course of action was to continue to Bristol.

• Emergency gear extension system used to extend the landing gear by gravity. Key elements of the report related to the management of repetitive defects:

MEL applied after 2 occurrences, but corrective actions applied after flight - 2, so could be considered as independent (i.e., not repetitive)

Safety gap analysis towards

Identification of repetitive defects: − Failures during previous flights -2 & -1 recorded in TLB, − Maintenance contacted for a later MEL possibility, − Crew aware of MEL applied, dispatch GEN 1 off, APU active. Uncertain if considered as “repetitive” − Fault addressed by application of MEL − Notification/ communication of repetitive defects: − When changing over, the pilots shared about the Gen 1 issue Repetitive defects as hazards to flight safety: − None − Significant effects of fault combined with reported unsuccessful transfer of AC ESS BUS via ALTN procedure caused by specific GCU failure. − GCU 1 replaced after flight -2, showed when investigated an history of similar fault (inexplicit Rogue unit) Resolution of the repetitive defects: n/a Other: n/a

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

AAIB 4/2009 France 15.09.2006 Incident Airbus A319/ G-EZAC/ easyJet

Proposed mitigating actions for the identified safety gaps

− Traceability of repetitive faults at component level “Rogue units”, response to SR 2008-089 does not appear to cover rogue units, it focuses on issues at airframe level. Was the SIB planned for 2016 released? As per the SRIS database, what started with a RMT (response June 2010) transposed into the issuance of a SIB (response April 2016) that was eventually replaced by a safety promotion action (response April 2021).

Already existing mitigating actions that may need enhancement

− For info in FCOM clearly defined reset procedure + record in log book. − No limitation of reset, but each reset to be recorded in logbook to allow identification of repetitive faults.

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8.2 Boeing 737-800, TC-JGE, Turkish Airlines, 25.02.2009

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

M2009LV0225_01 Netherlands 25.02.2009 Accident Boeing 737-800/ TC-JGE/ Turkish Airlines

Event summary/ Key elements

Event summary: − A Boeing 737-800 (flight TK1951) operated by Turkish Airlines was flying from Istanbul Atatürk Airport in Turkey to Amsterdam Schiphol Airport, on 25 February 2009. As this was a

‘Line Flight Under Supervision’, there were three crew members in the cockpit, namely the captain, who was also acting as instructor, the first officer who had to gain experience on the route of the flight and who was accordingly flying under supervision, and a safety pilot who was observing the flight.

− There were also four cabin crew members and 128 passengers on board. During the approach to runway 18 Right (18R) at Schiphol airport, the aircraft crashed into a field at a distance of about 1.5 kilometres from the threshold of the runway. This accident cost the lives of four crew members, including the three pilots, and five passengers, with a further three crew members and 117 passengers sustaining injuries.

− During the approach, and using the instrument landing system, it appeared that the left radio altimeter system suddenly indicated an erroneous height of -8 feet on the left primary flight display. In reality the height -8 cannot occur, however, the value itself is within the (design) height range of the radio altimeter system. As the erroneous radio height was lower than the required limit of 27 feet for the autothrottle to enter into the ‘retard flare’ mode and other conditions (described in paragraph 2.2.4) were being met, the autothrottle reduced the engine thrust to idle during the approach. This was in anticipation of the ‘touchdown’ (wheels on the runway), where the thrust levers are pulled fully aft by the autothrottle. This was possible because the left radio altimeter system had characterised the measured heights (including the -8 value) as ‘normal’ (usable). Under this condition the autothrottle, just like other systems on board, can use this height value. The ‘retard flare’ mode was indicated on the primary flight display as ‘RETARD’. At the same time the right-hand side autopilot (which used data from the right-hand side radio altimeter system) followed the glide slope signal. The aircraft was trimmed nose up in order to follow the glide slope and the airspeed decreased.

Key elements of the report related to the management of repetitive defects: − The maintenance documents of the aircraft did not contain any defects or technical complaints that still had to be resolved. (Crews’ awareness – Communication of repetitive

defects) − The only indication for a defect in the left radio altimeter system was the - 8 feet indication on the left primary flight display (Symptoms of the defect misleading crew) − The crews involved in previous flights had stated that these irregularities had proved not to be reproducible on the ground and/ or had not recurred during their return flights. For

this reason, the crews did not report the incident (The challenge about repetitive defects i.e., mainly/ purely relying on engineering to monitor unless crews are requested to report if a defect repeated or not)

− The radio altimeter system issues were discussed seven times during the six-weekly Operations meetings with pilots, fleet management and Engineering, Maintenance and Quality managers. These meetings did not result in informing pilots about the issues and the possible consequences of this for flight operations because the problems were not deemed to be a threat to safety. Turkish Technic Inc. representatives believed both radio altimeter systems were a backup for the other if either one failed. In their view there was a lack of information in the system documentation to comprehend the actual system autothrottle and radio altimeter system interaction. (Responses to repetitive defects short term i.e., MCC vs. long term i.e., reliability programme)

− Technical reliability issues were discussed during the Reliability Control Board Meeting chaired by the Turkish Airlines Technical management and also attended by the Turkish Airlines Flight Operations management. The Turkish Airlines Flight Safety and Quality Assurance department attended the meetings until October 2008. Between 16 February 2007 and 11 February 2009 the radio altimeter system issues were discussed four times, especially on TC-JGE, during these meetings. (Effectiveness of Reliability Programme i.e., taking corrective action such as planning downtime for troubleshooting or even grounding the aircraft or test flying before the defect is completely resolved)

− A complete overview of the regular maintenance performed on TC-JGE was available for the investigation. In accordance with the manufacturer specifications regular maintenance is not performed on radio altimeter systems. Maintenance will only be performed after a complaint from a crew member or when during maintenance it becomes evident that something is not working correctly. The aircraft underwent its last C-check on 20 October 2008 when all antennas were fitted with gaskets. The last A-check was carried out on 19 and 20 February 2009 just before the accident. Work was not performed on the radio altimeter system during these maintenance overhauls because complaints about the radio altimeter systems had not been written down in the maintenance documentation. (MSG-3 Should it consider developing tasks i.e., functional checks for those safety critical systems impacting on automation?)

− Several airlines, including Turkish Airlines, regarded the problems with radio altimeter systems as a technical problem rather than a hazard to flight safety. As a result, the pilots were not informed of this issue. (Risk assessment of repetitive defects)

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

M2009LV0225_01 Netherlands 25.02.2009 Accident Boeing 737-800/ TC-JGE/ Turkish Airlines

Safety gap analysis towards

Identification of repetitive defects: − The radio altimeter system issues were discussed seven times during the six-weekly Operations meetings with pilots, fleet management and Engineering, Maintenance and Quality

managers. These meetings did not result in informing pilots about the issues and the possible consequences of this for flight operations because the problems were not deemed to be a threat to safety. Turkish Technic Inc. representatives believed both radio altimeter systems were a backup for the other if either one failed. In their view there was a lack of information in the system documentation to comprehend the actual system autothrottle and radio altimeter system interaction. This demonstrates the need for repetitive defects to be robustly monitored on a daily basis without relying on the reliability programme.

− A complete overview of the regular maintenance performed on TC-JGE was available for the investigation. In accordance with the manufacturer specifications regular maintenance is not performed on radio altimeter systems. Maintenance will only be performed after a complaint from a crew member or when during maintenance it becomes evident that something is not working correctly. The aircraft underwent its last C-check106 on 20 October 2008 when all antennas were fitted with gaskets. The last A-check107 was carried out on 19 and 20 February 2009 just before the accident. Work was not performed on the radio altimeter system during these maintenance overhauls because complaints about the radio altimeter systems had not been written down in the maintenance documentation. (MSG-3 Should it consider developing tasks i.e., functional checks for those safety critical systems impacting on automation?)

Notification/ communication of repetitive defects:

− Since the maintenance documents of the aircraft did not contain any defects or technical complaints that still had to be resolved, the situational awareness of the flight deck crew was significantly reduced due to repetitive defects on a critical system not being visible to them.

Repetitive defects as hazards to flight safety:

− Several airlines, including Turkish Airlines, regarded the problems with radio altimeter systems as a technical problem rather than a hazard to flight safety. Clearly, Turkish Airlines was not the only airline treating such adverse reliability trends only as technical issues but not considering the associated flight safety risks. This demonstrates the need for a holistic approach to risk management within an airline i.e., both flight operations departments and CAMOs collectively risk assessing such repetitive defects and when they potentially impact on automation and crew workload, consider taking swift action including planning downtime or removing aircraft from service.

Resolution of the repetitive defects:

− Technical reliability issues were discussed during the Reliability Control Board Meeting chaired by the Turkish Airlines Technical management and also attended by the Turkish Airlines Flight Operations management. The Turkish Airlines Flight Safety and Quality Assurance department attended the meetings until October 2008. Between 16 February 2007 and 11 February 2009 the radio altimeter system issues were discussed four times, especially on TC-JGE, during these meetings. This clearly demonstrates the importance of taking corrective actions following the identification of adverse reliability trends to achieve an effective reliability programme.

Other: n/a

Proposed mitigating actions for the identified safety gaps

− TBC

Already existing mitigating actions that may need enhancement

− TBC

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8.3 Airbus A320, PK-AXC, Indonesia Air Asia, 28.12.2014

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.14.12.29.04 Indonesia 28.12.2014 Accident Airbus A320/ PK-AXC/ Indonesia Air Asia

Event summary/ Key elements

Event summary: Loss of control in flight. 4 occurrences of master caution “AUTO FLT RUD TRV LIM SYS”, ECAM procedure followed for the 3 first instances. Then after the 4th, pilot actions recorded show FAC CBs pulled off. Resulting in EW AUTO FLT FAC 1 FAULT & AUTO FLIGHT FAC 2 FAULT, consequently auto pilot and auto thrust disengaged and the flight control system reverts to Alternate law (protection lost). First officer actions led to Aircraft entering an upset condition, stall warning activating until end of recording Key elements of the report related to the management of repetitive defects: Failure to have a global view of the repetitive nature of the fault.

Safety gap analysis towards

Identification of repetitive defects: loss of RTLU, rudder travel limiter failures (either or both channels) occurred 23 times in the preceding year. Maintenance report 1 (tech log book) shows 5 pilot’s reports related to RTLU in November, and 9 in December. Maintenance report 2 (deferred defect log book) notes an RLTLU defect inserted on Dec 19th, then closed after scheduled flight, as PFR showed no fault recorded. ops test, no faults. Notification/ communication of repetitive defects: MR1 shows records of the instances of the failure condition but does not mention its “repetitive” nature. Repetitive defects as hazards to flight safety: Normalisation of resets be it on ground or in flight, on same system computers Resolution of the repetitive defects: n/a, treated as individual defect Other: n/a

Proposed mitigating actions for the identified safety gaps

Identification (and record as such) of the repetitive nature of the failure is key to trigger fault isolation as early as possible. This in order to reduce exposure time.

Already existing mitigating actions that may need enhancement

Clarification of allowable resets for flight crew vs. maintenance

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8.4 Boeing 737-800, CN-ROJ, Royal Air Maroc, 30.12.2016

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator BEA2017-0003 France 30.12.2016 Serious Incident Boeing 737-800/ CN-ROJ/ Royal Air Maroc

Event summary/ Key elements

Event summary: The aircraft was being vectored to the ILS of runway 06 at Paris-Orly (Val-de-Marne). The meteorological conditions required a category 3 instrument approach (CAT III ILS). After receiving the approach clearance, the crew twice tried to engage the second autopilot (A/P B). The non-reception of radio-altimeter (RA) 2 data by the flight control computer (FCC B) prevented the engagement of A/P B and caused the disengagement of A/P A. The crew re-engaged A/P A and the aircraft was diverted to Lyon-Saint Exupery airport, where conditions permitted a CAT I ILS approach, which could be carried out with only one A/P functioning. During the approach, an untimely right turn was commanded by the A/P due to the erroneous data from the IRS module of the left Air Data Inertial Reference Unit (ADIRU). The invalidity of the data supplied by the left ADIRU then led to the disengagement of A/P A. The captain then flew manually with the Flight Directors (F/D) displayed on the Primary Flight Display (PFD). The crew first tried to return to the path. As the deviation from the path compromised continuing the approach, they flew a missed approach and then engaged A/P B. The aeroplane had just been transferred to the Approach again when the L IRS FAULT warning was activated causing the disengagement of A/P B, and the disappearance of the pitch, roll and heading data along with the F/D bars from the left PFD. The captain again flew manually while carrying out from memory, one of the actions of the IRS FAULT checklist, namely, IRS Transfer Switch - BOTH ON R. The two FCC thus used the data supplied by the right ADIRU. The pitch, roll and heading were displayed again on the left PFD and the F/D bars reappeared. During the second approach and the interception with the localizer, and after re-engaging A/P B and transferring the controls to the co-pilot, the captain informed the controller that he had positioning problems. The controller continued the radar vectoring. On capturing the Glide, A/P B automatically disengaged due to FCC B not receiving data from RA 2. The F/D disappeared from both sides. The co-pilot then transferred the controls to the captain. The latter informed the Approach controller that he was continuing in manual flight. The flight was transferred to the Tower controller. The approach, in manual and without the F/D, was not stabilized with respect to either the path and slope or the aeroplane’s speed and configuration. Several EGPWS “SINK RATE”, “GLIDE SLOPE” and “TOO LOW TERRAIN” warnings were activated on final. Key elements of the report related to the management of repetitive defects:

− The investigation showed that the malfunctions linked to RA 2, observed during the incident flight, were intermittent faults and that they had existed on CN-ROJ for at least six months (as recorded by the non-volatile memories (BITE) of the FCC). In the six months up until the day before the occurrence, this fault linked to RA 2 was recorded 35 times, including 16 times since 9 December. During the occurrence flight, this same fault, RADIO ALT-2 (J1B-B04, A04) was recorded seven times in FCC B.

− The analysis of the QAR data and fault messages recorded in the FCC BITE brought to light that the RAM crews did not systematically report the technical malfunctions in the CN- ROJ TLB.

Safety gap analysis towards

Identification of repetitive defects:

− The RAM’s Operations Manual specifies that the captain must make a detailed entry in the TLB about any fault likely to affect airworthiness or operating safety, including the safety systems. This principle was not sufficiently complied with by the RAM pilots over the period analysed by the BEA. Disappearance of the F/D, the ADIRU malfunctions and the A/P automatically disconnecting were not systematically reported. Systematic reporting of the faults and anomalies encountered by the crew gives the maintenance department the possibility of correcting the problems or in the case of intermittent faults, of monitoring their evolution. It would have permitted the RAM maintenance department to be better prepared for resolving the problems encountered on this plane. In particular, it would have probably been able to identify the communication problem between RA 2 and FCC B sooner and to replace the left ADIRU more quickly.

− The tests carried out indicated that the fault associated with RA 2 was not confirmed on the ground and that as a consequence, it was an intermittent type fault. This fault could be systematically found by the maintenance personnel in the fault history of the Control Display Unit (CDU) (DFCS BITE procedure).

Notification/ communication of repetitive defects:

− The reading of the maintenance documents suggests that the RA 2/ FCC B fault did not reappear during the ground tests, thereby indicating, in accordance with the fault isolation manual, that either it was intermittent, or it only appeared in flight conditions. The Boeing procedure indicates that, in this case, the maintenance technicians must comply with the operator’s policy for processing intermittent faults, use their judgement and the operator’s maintenance history and specifically monitor the aeroplane in question.

Repetitive defects as hazards to flight safety:

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator BEA2017-0003 France 30.12.2016 Serious Incident Boeing 737-800/ CN-ROJ/ Royal Air Maroc

− Although it appeared on several occasions and its consequences were notified by the crews, the base maintenance centre was not able to solve this fault, resulting, on the day of the event, in a degraded aircraft, presenting automated system problems mainly in the approach phase.

− During the flight, the crew were confronted with various malfunctions either linked to technical failures or of an operational nature (left ADIRU and RA 2). Confronted with malfunctions which they could not explain, foresee, or interconnect, their confidence in the plane progressively decreased, their attention being particularly focused on the fuel level which they believed insufficient. Each instant delaying the landing risked seeing new faults appear. The crew had thus progressively passed from conventional management in normal mode, at the beginning of the flight, to “emergency” mode management with them wanting to land as quickly as possible.

Resolution of the repetitive defects:

− Following the crew’s report of a problem linked to RA 2 on 10 December 2016, RAM replaced it. However, the fault occurred again on 12 December 2016. The cause of the fault was therefore not removed. It then reoccurred on 25 December 2016 after 54 problem-free flights. FCC B was replaced three days after the occurrence, on 2 January 2017, without the problem disappearing. It was therefore highly likely that the malfunction was due to neither RA 2 nor FCC B, but due to the connection between the two systems.

Other: Other factors that contributed to the escalation to that serious incident besides the presence of repetitive defects:

− The concomitance of two independent failures within two separate systems where the cause of the failures, the absence of any link and the consequences were difficult for the crew to determine, without appropriate information in the operational documentation or sufficiently salient warnings emitted by the aircraft systems.

− The operating logic of the FCC which does not monitor the inertial data provided by the ADIRU, except for approaches with the two A/P engaged. The FCC was not designed to, nor was it required for certification, to monitor the ADIRU inputs.

− The ADIRU internal monitoring logic with respect to the validity of the inertial data transmitted to other systems. The activation criteria of the “Drift Angle” fault, which in turn activates the IRS FAULT warning, can cause the latter to appear at a late stage with respect to the start of the ADIRU IR module malfunction.

Proposed mitigating actions for the identified safety gaps

− The crew reports play an essential role in the maintenance actions that will be carried out on the aircraft a posteriori. If a fault which occurs in flight is not reported, it will not be the subject of a corrective maintenance action or specific monitoring by the department responsible for monitoring and managing faults. Systematic reporting of the faults and anomalies encountered by the crew is paramount. [related to safety recommendation FRAN 2021-015]

− Operators were asked to implement a policy for processing intermittent faults, with these faults being specifically monitored on several consecutive flights, reminding that it is possible to access the faults recorded by the main computers through the Cockpit Display Unit, after a flight, even if they are no longer active on the ground. [related safety recommendation FRAN 2021-016]

Already existing mitigating actions that may need enhancement

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8.5 Boeing 737-800, F-GZHO, Transavia, 08.02.2018

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator BEA2018-0071 France 08.02.2018 Incident Boeing 737-800/ F-GZHO/ Transavia France

Event summary/ Key elements

Event summary: On the first two flights after base maintenance event, IAS DISAGREE, ALT DISAGREE and AOA DISAGREE fault messages were triggered. First flight continued to destination with ALT and AOA disagree between left and fight PFD. On the second flight, after initial climb captain decided to return to original airport. Investigation revealed RH AOA sensor failure. Sensor chemical contamination was found (epoxy), which most probably occurred during the manufacturing process. QAR data showed that RH AOA sensor was not performing well since aircraft first flight (sensor was installed in the aircraft at factory). However, no fault message was triggered in cockpit during the three years of aircraft operation till the base maintenance event. However, it is possible that the handling of the sensor during base maintenance task exacerbated the dysfunction of the sensor without the technicians realising this. The technician working on the aeroplane between the two flights not using the FIM. Its use would have ensured that a more complete check was carried out, the failure would have probably been detected and the sensor replaced. Key elements of the report related to the management of repetitive defects: This event is not related to inadequate management of repetitive defect, as the faults were only triggered in two consecutive flights. It is more related to wrong/incomplete trouble shooting, not identifying the cause of the defect and releasing to service the aircraft.

Safety gap analysis towards

Identification of repetitive defects: The technician working on the aeroplane between the two flights not using the FIM. Its use would have ensured that a more complete check was carried out, the failure would have probably been detected and the sensor replaced. Notification/ communication of repetitive defects: N/A Repetitive defects as hazards to flight safety: N/A Resolution of the repetitive defects: N/A Other: N/A

Proposed mitigating actions for the identified safety gaps

N/A

Already existing mitigating actions that may need enhancement

Following trouble shooting manual for defect rectification.

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8.6 Airbus A320, ES-SAN, Smartlynx Airlines, 28.02.2018

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

A2802118 Estonia 28.02.2018 Accident Airbus A320/ ES-SAN/ Smartlynx Airlines Estonia

Event summary/ Key elements

Event summary: − Runway excursion during training flight program: 5 touch & go cycles, 1 go around, then full stop landing for each of several successive trainees. − Crew members: Instructor in pilot seat, trainee in first officer seat & safety pilot in jump seat − During several touch & go, EW “F/CTL ELAC 1 PITCH FAULT” and/or “F/CTL ELAC2 PITCH FAULT” triggered when the instructor stopped the pitch trim wheel close to the trim take

off position. − When both EW triggered at same time, it led to a reversion from normal to pitch alternate law (EW: “F/CTL ALTN LAW”). Repeated faults were handled using ELAC resets (in line

with current QRH). in total 9. − While the 4th trainee performed his third touch & go, ELAC2 pitch fault re-occurred. Yet, as during the previous cycle, ELAC1 pitch fault triggered and was not reset, this induced a

reversion in alt law. Additionally, due to a bounce, the ground condition was not exactly sensed simultaneously in the COM and MON units of the SEC computers, leading to loose pitch control also by the SECs. − Then, with thrust levers in TOGA detent, the A/C approached the rotation speed, pitch up sidestick orders had no effect. EW “F/CTL L+R ELEV FAULT” “MAN PITCH TRIM …USE”

triggered. The A/C speed increase led to slightly lift off with pitch control available only with trim wheel, roll control available in direct law using sidesticks…..Idle thrust, conf 2 to conf 1, gear up ordered, A/C flew down from 48 ft, hit the runway (engine, LG damaged ) then got airborne again in very degraded condition, manual pitch trim only was used… aircraft both engines failed during return leading to final landing 150m before runway threshold.

Key elements of the report related to the management of repetitive defects: − The aircraft had no known technical issues before the flight. Potentially out of scope of this study. − Continued training program despite repeated NoGo E/W

Safety gap analysis towards

Identification of repetitive defects: − In real time during training, same trainer & safety pilot − The crew made 5 ELAC1 resets and 4 ELAC2 resets. Notification/ communication of repetitive defects: − None Repetitive defects as hazards to flight safety: − Normalisation of resets in flight on same system or computer (9 occurrences of resets) − Same failure, on a critical function repeating steadily. − No step back for considering/assessing criticality of function losses and possible detrimental combination(s) E1+E2, and E1+E2 + other by referring to MEL for instance.

Resolution of the repetitive defects: n/a, because occurred during flight Other: n/a

Proposed mitigating actions for the identified safety gaps

n/a

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

A2802118 Estonia 28.02.2018 Accident Airbus A320/ ES-SAN/ Smartlynx Airlines Estonia

Already existing mitigating actions that may need enhancement

− Clarification of allowable resets for flight crew (QRH).

− Clarification of MEL for consideration in training flight context (FCTM).

− Make safety pilot awareness about repetitive defect handling during training flights.

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8.7 Boeing 737-8 (MAX), PK-LQP, PT. Lion Mentari Airlines, 29.10.2018

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.18.10.35.04 Republic of Indonesia 29.10.2018 Accident Boeing 737-8/ PK-LQP / PT. Lion Mentari Airlines

Event summary/ Key elements

Event summary: − On 29 October 2018, at about 0632 Local Time (23:32 UTC 28 October 2018), a PT Lion Mentari Airlines (Lion Air) Boeing 737-8 (MAX) aircraft registered PK-LQP, was being operated

as a scheduled passenger flight from Soekarno-Hatta International Airport (WIII), Jakarta with intended destination of Depati Amir Airport (WIPK), Pangkal Pinang, when the aircraft disappeared from radar after informing Air Traffic Controller (ATCo) that they had flight control, altitude and airspeed issues. The aircraft impacted the water in Tanjung Karawang, West Java, all person on board perished and the aircraft destroyed.

− On 26 October 2018, the SPD (speed) and ALT (altimeter) flags on the Captain’s primary flight display first occurred on the flight from Tianjin, China to Manado, Indonesia. Following reoccurrence of these problems, the left angle of attack (AOA) sensor was replaced in Denpasar on 28 October 2018.

− The installed left AOA sensor had a 21° bias which was undetected during the installation test in Denpasar. The erroneous AOA resulted in different indications during the flight from Denpasar to Jakarta, including IAS (indicated airspeed) DISAGREE, ALT (altitude) DISAGREE, FEEL DIFF PRESS (feel differential pressure) light, activations of Maneuvering Characteristics Augmentation System (MCAS) and left control column stick shaker which were active throughout the flight. The flight crew was able to stop the repetitive MCAS activation by switched the stabilizer trim to cut out.

− After landed in Jakarta, the flight crew reported some malfunctions, but did not include the activation of stick shaker and STAB TRIM to CUT OUT. The AOA DISAGREE alert was not available on the aircraft therefore, the flight crew did not report it. The reported problem would only be able to rectify by performing tasks of AOA Disagree.

− The following morning on 29 October 2018, the aircraft was operated from Jakarta with intended destination of Depati Amir Airport, Pangkal Pinang. According to the DFDR and the CVR, the flight had same problems as previous flight from Denpasar to Jakarta.

− The flight crew started the IAS DISAGREE Non-Normal Checklist (NNC) but did not identify the runaway stabilizer. The multiple alerts, repetitive MCAS activations, and distractions related to numerous ATC communications contributed to the flight crew difficulties to control the aircraft.

Key elements of the report related to the management of repetitive defects: − The AOA DISAGREE alert was not correctly enabled during Boeing 737-8 (MAX) development. As a result, it did not appear during flight with the mis-calibrated AOA sensor, could

not be documented by the flight crew and was therefore not available to help maintenance identify the mis-calibrated AOA sensor. − The replacement AOA sensor that was installed on the accident aircraft had been mis-calibrated during an earlier repair. This mis-calibration was not detected during the repair. The

investigation could not determine that the installation test of the AOA sensor was performed properly. The mis-calibration was not detected. − After LNI043 was airborne, the left control column stick shaker was active and several messages appeared. The Captain of LNI043 was aware to the aircraft condition after discussion

with the engineer in Denpasar. This awareness helped the Captain to make proper problem identification. − Lack of documentation in the aircraft flight and maintenance log about the continuous stick shaker and use of the Runaway Stabilizer NNC meant that information was not available

to the maintenance crew in Jakarta nor was it available to the accident crew, making it more difficult for each to take the appropriate actions. − The investigation found that the engineers were prone to entering the problem symptom reported by the flight crew in the Interactive Fault Isolation Manual (IFIM) first instead of

reviewing the Onboard Maintenance Function (OMF) maintenance message. Conducting this method might lead the engineers into the inappropriate rectification task. − The investigation found that all Aircraft Flight Maintenance Log (AFML) pages received by the investigation did not contain fault codes. The absence of the fault code reported by

the flight crew may increase the workload of the engineer and prolong the rectification process. − The OMF has the history page which contains record of the aircraft problems which can be utilised as a source for aircraft problem monitoring. Batam Aero Technic (BAT), the

approved maintenance organisation, has not utilised the OMF information as the source of aircraft problem monitoring.

Safety gap analysis towards

Identification of repetitive defects: − The definition of an aircraft repetitive problem was different between Lion Air CMM and BAT AMOQSM. The Lion Air CMM described that the aircraft problem categorized as the

repetitive problem if discrepancy twice recurs on the same aircraft during 30 consecutive days of operation, while BAT AMOQSM stated three times within 30 consecutive days. This difference indicated that the Lion Air did not monitor the repetitive problem policy of the BAT as a subcontracted entity.

− Incomplete report of the mechanical irregularities experienced during previous flight LNI043, where the flight crew was able to successfully land the accident aircraft while experiencing the same conditions as the accident flight. The Captain did not mention the activation of the stick shaker, and did not report the stabilizer runaway and the use of the

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.18.10.35.04 Republic of Indonesia 29.10.2018 Accident Boeing 737-8/ PK-LQP / PT. Lion Mentari Airlines

STAB TRIM CUTOUT guarded switches or that he had to use manual trim for the majority of the flight and the landing. The requirement to report all known and suspected defects is very critical for engineering to be able to maintain the airworthiness of the aircraft.

− There was no requirement to perform AOA value test. The IAS and ALT disagree reported which occurred on the LNI043 flight which was caused by AOA sensor bias, would not be able to solve by both IFIM tasks of ‘ALT DISAGREE shows on PFD - Captain’s’ and ‘IAS DISAGREE shows on PFD - Captain’s’. The AOA DISAGREE message was not enabled and was inhibited; therefore, it did not appear on the LNI043 flight. The inhibited AOA DISAGREE message contributed to the inability of the engineer to rectify the failure of the AOA sensor.

− The AFML is the only source of the daily aircraft problem monitoring in which the problem may be identified by the flight crew or engineer. If the aircraft problem is not stated in the AFML, the repetitive problem may not be detected. The investigation found that the SPD and ALT flags problem was reported twice in the AFML on 26 and 27 October 2018 while the DFDR recorded the problems occurred three times. The SPD and ALT flags problem during the flight from Manado to Denpasar on 27 October 2018 was recorded on the DFDR but was not reported in the AFML. The absence of aircraft problem report affected the repetitive problem identification.

− The OMF and Interactive Fault Isolation Manual (IFIM) provide trouble shooting guidance for the engineer. The investigation found that the engineers were prone to entering the problem symptom reported by the flight crew in the IFIM first instead of reviewing the OMF maintenance message. Conducting this method might lead the engineers into the inappropriate rectification task.

− The Fault Reporting Manual (FRM) helps to directly appoint the proper IFIM task by fault code for particular problem entered by the flight crew. The fault code may direct the engineer to the relevant problem and prevent the unnecessary presentation of several faults, IFIM tasks or maintenance messages. The investigation found that all AFML pages received by the investigation did not contain fault codes. The absence of the fault code reported by the flight crew may increase the workload of the engineer and prolong the rectification process.

Notification/ communication of repetitive defects: − After replacement of the left AoA sensor that resulted in misalignment because of incorrect installation, the flight crew of the LNI043 flight was briefed prior flight by the engineer

about the repetitive aircraft problems, and the rectification that has been performed. Repetitive defects as hazards to flight safety: − The SPD and ALT flags were reported multiple times by the flight crew during three out of four flights before identifying the left AoA sensor as the potential root cause. − After the fourth flight of that day, the left AoA sensor was not replaced because of lack of spare. Despite the identified left AoA signal failure, the left ADIRU and SMYD 1 C/B were

reset, DFCS test successfully passed. The flight crew was then recommended to perform the planned flight to the next stop, where the AoA could be replaced. The SPD and ALT flags on the Captain’s PFD most likely had appeared again after the engine started. Although prior to take off, the MEL was not considered. Indicated airspeed or altimeter are NO GO items. The aircraft was released with a known possible recurring defect, that in addition was a NO GO item as per the MEL.

Resolution of the repetitive defects:

− The investigation did not find any evidence of handling the problem as repetitive according to the CMM, other than the statement on the AFML for replacement AOA sensor was ‘due to repetitive problem’.

Other:

− n/a

Proposed mitigating actions for the identified safety gaps

− Implement automation for fault/ failure reporting to populate the aircraft technical logbook − Promote the importance of fault isolating/ troubleshooting instead of fault clearance − Address repetitive defects as hazard to flight safety − Communicate repetitive defects adversely affecting flight critical systems to the flight crew prior to flight

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.18.10.35.04 Republic of Indonesia 29.10.2018 Accident Boeing 737-8/ PK-LQP / PT. Lion Mentari Airlines

Already existing mitigating actions that may need enhancement

− CAMO repetitive defects management

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8.8 Airbus A319, N521NK, Spirit Airlines, 15.02.2020

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

ENG20LA016 United States of America 15.02.2020 Incident Airbus A319/ N521NK/ Spirit Airlines

Event summary/ Key elements

Event summary: − Loss of both electrical main generators in approach. − Emergency Electrical configuration, Ram Air Turbine (RAT) extended and activated. − Landing with no further incident. Key elements of the report related to the management of repetitive defects: − Similar in flight event 2 legs before, similar losses of functions. − Three other previous similar cases on ground (during single engine taxi after landing)

Event summary: On 15 February 2020, an Airbus A319-132 aircraft equipped with 2x IAE V2524-A5 engines experienced dual loss of Integrated Drive Generators (IDG), on approach to Sacramento International Airport, California. The fault resulted dual loss of AC BUS 1 and 2, prompting loss of several flight displays and automatic RAT extension to provide electric power to vital systems. The aircraft landed without further incident. The aircraft produced similar symptoms prior to this flight incident on 19th January, on 23rd and 29th January, finally on 14th February. Although troubleshooting has been performed, and maintenance actions carried out i.a.w Airbus AMM and TSM, the root cause of the previous occurrences were not found, but the aircraft was dispatched for operation. The Operator did not contact the OEM as per TSM indication; therefore, the root cause of the previous safety issues could not be found. Further investigations to the component revealed, after analysis of the NVM (Non-Volatile Memory) that one IDG failed their respective frequency control check confirmed by specific fault code as well (145) and the other failed under specific conditions. In the teardown of the IDG-s, it was found that internal cylinder blocks linked to internal hydraulic were significantly worn beyond design limit, which were later on identified and confirmed as root cause of the incident. Key elements of the report related to the management of repetitive defects:

− The unidentified root cause of the defect.

− The repetitiveness of the incident and uneven distribution of events, especially with increase of time intervals in-between.

− The (lack) of instruction of the OEM to the Operator for identifying a possible root cause and general guidance in the TSM. Operator did not approach OEM.

Safety gap analysis towards

Identification of repetitive defects: − Failure conditions troubleshot as individuals.

Notification/ communication of repetitive defects: − Unknown Repetitive defects as hazards to flight safety: − Obvious critical failure in flight, Electrical emergency configuration. − Electrical emergency configuration occurred twice. After the first one, troubleshooting

& power assurance run performed with no findings, the aircraft was returned to service.

− Lack of understanding of nature and criticality of the failure condition during the first inflight event. Induced repetition on incident flight.

Identification of repetitive defects: The repetitiveness in this specific occurrence shows increase in time interval in between two occurrences, so it is not a good indicator for identification (at some airlines it is not even a repetitive defect i.a.w their approved procedure). The re-appearance is a good mean to check the commonality between occurrences (e.g., single engine taxi, and failure subsequent of GEN 1 and 2 with time offset, imposes a similar load to the other -still operational- IDG.) Notification/ communication of repetitive defects: The workorders on the complaint are not very informative and the consulted NTSB docket are weak in term of content and there is no evidence of identified PFR warning/ fault messages on workorders previously. (NTSB Docket - Docket Management System). Repetitive defects as hazards to flight safety:

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

ENG20LA016 United States of America 15.02.2020 Incident Airbus A319/ N521NK/ Spirit Airlines

Resolution of the repetitive defects: − Airbus contacted after second in flight occurrence

Other: n/a −

Fault not confirmed/ not found may not mean that the aircraft is fault free. It may mean, that the fault is appearing under specific conditions, especially if it already happened. For this, a proper system knowledge and understanding of the defect interpretation, together with historical fault check is primordial. Otherwise, even if it looks clear, a potential unsafe aircraft can be dispatched for further operation. Resolution of the repetitive defects:

− OEM involvement, identification of the fault code (with OEM help) and effective maintenance action: IDG replacement.

− For the proper teardown of the problem (identify that the fault code 145 is linked to IDG frequency control and then internal parts might causing this problem) requires OEM expertise.

− After such involvement of OEM, a prompt answer towards the CAMO and Part-145 is required: replace the IDG.

− The in-depth understanding and correlation between events are not part of the TSM and cannot be solely linked to Part-145 organization. This requires a better system understanding and engineering overview which can be part of the CAMO but mainly this expertise is only on the OEM side.

Other: -

Proposed mitigating actions for the identified safety gaps

− Identification as repetitive ; MIS needs to be able to highlight RF (particularly on critical systems)

− Awareness on assessment of the of criticality

1. The occurrence safety criticality must be considered during establishment of repetitive defect handling procedure.

2. A sub-process can be established that requires historical fault check on the aircraft, depending on safety criticality, to identify potential latent hazards in the system.

N.B. As a result of this incident, Airbus has improved their TSM by incorporating steps to direct maintenance towards a direct extraction of the post flight report (PFR) and troubleshooting data (TSD) from the GCUs.

Already existing mitigating actions that may need enhancement

− Improve awareness in TSM to deal with repetitive faults TSM – clearer guidance for operator personnel on the action to be taken if a fault is not found.

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8.9 Airbus A321, G-POWN, Titan Airways, 26.02.2020

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

AAIB 1/2021 United Kingdom 26.02.2020 Incident Airbus A321/ G-POWN/ Titan Airways

Event summary/ Key elements

Event summary: − The aircraft just underwent a biocide shock treatment on its fuel system further to a

moderate microbial contamination that was detected during scheduled maintenance. − Following this treatment using Kathon biocide, abnormalities with the operation of

both engines occurred several flights before the incident. − Incident flight: at around 500 ft, the No 1 engine began to surge… then later, the crew

received indications that the No 2 engine had stalled. The crew established that the engines were more stable at low thrust settings and that those settings were sufficient to maintain a safe flightpath. They continued the approach. The aircraft landed uneventfully.

Key elements of the report related to the management of repetitive defects: Mainly communication between crews of successive flights and with tech engineers & maintenance − Two legs with issue(s) before incident flight.

• Leg -3: Crew A, contacted engineer for advice and briefed crew B on arrival about issue experienced at engine 1 start

• Leg -2: n/a, Engines functioned normally.

• Leg -1: Crew B notified the operator using ACARS. Eng 1 needed three start cycles. Later, “Eng 2 stall“ twice experienced during descent. Mayday. On ground, technical control contacted by phone, issue recorded in TLB. Crew B liaised with crew A & with tech. engineer, No fault found, engine stall defect and certificate of release signed off

• nb: inappropriate procedure (TSM) applied.

• Commander A mentioned he would check engine control indications before take- off by accelerating engines to 50% N1 for longer than usual.

− Incident flight

• Eng 1 start issues. Crew A contacted technical control. Engine 1 started at third attempt. Crew A contacted technical control again who advised certainly due to ignition fault that should be resolved once engine running.

• Engine control indications checked ok, take off commenced…Engine 1 surging…. engine 2 stall…

Event summary: The aircraft took off from London Gatwick Airport Runway 26L at 0009 hrs on 26 February 2020. At ~500 ft AGL, #1 (left) engine began to surge. The commander declared a MAYDAY and turned right downwind for an immediate return to the airport but, shortly afterwards, the crew received indications that the #2 engine had stalled. The crew established that the engines were more stable at low thrust settings and the thrust available at those settings was sufficient to maintain a safe flightpath. They continued the approach and the aircraft landed at 0020 hrs. Key elements of the report related to the management of repetitive defects:

− ECAM alerts that do not provide the flight crew and maintenance personnel with a clear correlation to the actual root cause of the fault.

− Assumption that the fault condition does not longer existing if an ECAM alert self- clears, as stated in the OEM’s Flight Crew Techniques Manual (FCTM).

Safety gap analysis towards

Identification of repetitive defects: − Crews A & B seemed aware of a potentially developing situation, they had exchanges

about aircraft recent & current status and also shared with technical engineer and line maintenance. Yet, all issues at engine start were not recorded in TLB.

− Line engineer not aware of recent base maintenance and history of start failures on the flights following the maintenance

Identification of repetitive defects: ENG X HP FUEL VALVE - ECAM alert ENG X STALL - ECAM alert Notification/ communication of repetitive defects: Via aircraft technical logbook and verbally to the flight crew by maintenance personnel.

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

AAIB 1/2021 United Kingdom 26.02.2020 Incident Airbus A321/ G-POWN/ Titan Airways

− The Technical Control engineer expected that if there was a fault, a fault message or indication problems would occur and the pilots would return to stand

Notification/ communication of repetitive defects: − Incomplete record in TLB. − Assumption by technical on pilot decision to return to stand if failure reoccurred. Repetitive defects as hazards to flight safety: − Common cause affecting redundant critical systems. − Contamination with undissolved Kathon induced repetition of same faults Resolution of the repetitive defects: n/a Other: Assessment of a previous engine 1 start problem as “a start fault, nothing more than that” by technical control engineer. Too little background information available.

Repetitive defects as hazards to flight safety: Engine related fault due to out of specification fuel, resulting in partial loss of thrust of both engines simultaneously. Resolution of the repetitive defects: Replacement and/ or servicing of parts contaminated by excessive concentrations of biocide in fuel. Removal of fuel with excessive biocide concentration from aircraft fuel tanks and associated decontamination tasks. Other: N/A

Proposed mitigating actions for the identified safety gaps

None − If enough doubt exists where a non-standard procedure is considered necessary e.g., an engine run prior to take-off on a commercial flight, this should raise flag with flight crew and maintenance personnel that troubleshooting must be continued prior to dispatch.

− Review guidance in the OEM’s FCTM that currently states that the fault condition does not longer existing if an ECAM alert self-clears. Consider adding specific guidance that all faults, even those that self-clear or are reset successfully must be entered in the aircraft technical logbook.

− Consider guidance to explain that ECAM alerts are generated by sensors that only measure effect, and do not necessarily provide flight crew and maintenance personnel with a clear means to determine root cause at time of failure and thus may be a barrier to optimal decision making. This must be carefully worded so as not to instil doubt of the certified reliability of the ECAM system.

− Consider analysis by OEM for any additional guidance/ troubleshooting for fault indications that could be manifestation of root cause that can potentially affect multiple redundant systems, e.g., fuel contamination.

Already existing mitigating actions that may need enhancement

Awareness in TLB The fuel contamination caused abnormal fuel flow values during the engine starts during the event and preceding flights that were not evident to the flight crew or maintenance personnel. This parameter should be considered in the post-flight analysis of engine/ flight data as potentially useful indicator of fuel contamination. Although engine/ flight data analysis is already in place, an enhancement would be to have a quicker turnaround of the analysis, such that it can be part of the Line maintenance real-time troubleshooting tools, rather than only a long-term trend analysis. With the advent of wide availability of AI, this

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

AAIB 1/2021 United Kingdom 26.02.2020 Incident Airbus A321/ G-POWN/ Titan Airways

methodology may be used on an ever-increasing number of parameters that modern aircraft record.

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8.10 Boeing 737-500, PK-CLC, PT Sriwijaya Air, 09.01.2021

Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.21.01.01.04 Indonesia 09.01.2021 Accident Boeing 737-500/ PK-CLC / PT Sriwijaya Air

Event summary/ Key elements

Event summary: − During climbing, the autopilot (A/P) directional control was changed from LNAV to HDG SEL and subsequently the vertical control changed to Pitch V/S and MCP (Mode Control Panel)

SPD. These changes required less engine thrust therefore the engine power reduced. The FDR recorded that left thrust lever moved backward and the left engine thrust decreased, however the right engine remained at its climb power setting, resulting in an asymmetric thrust condition. The investigation concluded that the autothrottle (A/T) system command being unable to move right thrust lever was a result of friction or binding within the mechanical system except the torque switch mechanism. The maintenance record showed that the A/T problem was reported 65 times since 2013 and the problem was unsolved and still exist on the accident flight.

− The Cruise Thrust Split Monitor (CTSM) system delayed disengaging the A/T and the thrust asymmetry continued to increase. The investigation believed that the delay of CTSM was due to an error in the spoiler signal value.

− As the thrust asymmetry became greater, the aircraft turned to the left instead of to the right as intended. The aircraft entered an upset condition, and the pilot was unable to recover the situation. Inadequate of upset prevention and recovery training contributed to the inability of the pilot to prevent and recover from the upset condition.

Key elements of the report related to the management of repetitive defects: − The aircraft was delivered to the Sriwijaya Air in 2012. The investigation noted that the since 2013 until the accident flight, there were 65 problems related to the A/T system reported. − The engineer’s actions in attempting to address the reported A/T problem were dominated by cleaning the connectors (48%). Replacements of several components were also

performed. The aircraft maintenance log (AML) recorded replacement of right engine, however the A/T problems still occurred, this showed that the problem was not related to the engine. The engineer actions did not solve the problem.

− The AML also recorded 61 problems related to the difference of engine parameters between left and right engines, including 32 times of A/T disengagement. Most of the differences in the engine parameters were reported during the aircraft on descent. The AML also recorded the lack of thrust lever movement of the right engine as follow:

• Six pilot reports related to slow response of the right thrust lever to flight idle during descent.

• Two pilot reports related to the right thrust lever hard to move. − The lack response or hard to move the right thrust lever indicated that the thrust control cable experienced friction or binding within the mechanical system. A high enough friction

force occurring in the throttle control cable can cause the torque switch to open and the throttle lever stopped being moved by the A/T system until the friction force is reduced.

Safety gap analysis towards

Identification of repetitive defects: − Since 2013 until the accident flight, the AML data recorded 65 pilot reports related to the A/T system and 61 problems related to the differences in engine parameters. The AML

record showed that 48% of the A/T system maintenance actions involved cleaning of the electrical connectors.

− The connector cleaning is part of the Electronic Wiring Interconnection System (EWIS) preliminary action however, the connector cleaning might have become a habit during the rectification as it is the easiest rectification action and appeared to be successful. Some of the reported problem appeared to be solved after the connector cleaning performed. The AML record showed that after the engineer had cleaned the electrical connector, the BITE test was performed which showed the result of ‘no faults’.

− If the cleaning of the electrical connectors did not solve the A/T system problem, the Flight Management Computer (FMC) Control Display Unit (CDU) provides tools for thorough trouble shooting as directed by the Aircraft Maintenance Manual (AMM). The use of FMC CDU is part of AMM trouble shooting therefore, the AMM reference must be included in the AML as required in the Sriwijaya Air Aircraft Maintenance Procedure (AMP). The ‘no faults’ results might had been generated by the A/T computer that did not find any fault in the computer nor any electrical power connection to the A/T computer and not considered the reliability of the information from each component of the A/T system. The maintenance actions were stopped after the BITE test resulted ‘no faults’.

− Among the 61 pilot reports relating to the differences in engine parameters, more than 53 reports occurred during the aircraft descent. The differences in engine parameters during aircraft descent and the right thrust lever late on the take-off roll while the A/T engaged, most likely might have resulted in the thrust levers split.

− The Quick Access Recorder (QAR) data recorded 7 thrust levers split occurrences between 2020 and 2021. No pilot reported on these occurrences in the AML. Most of the pilots stated that they did not recall the occurrences.

− Based on the maintenance history the engineer referring to the AMM chapter 22-04-10 (A/T System BITE Trouble Shooting) showed a frequency of 18%, while the engineers referring to the AMM chapter 22-31-00 (A/T System – Description and Operation) was 25%. None of the maintenance history recorded the performance of the AMM chapter 71-00-49 (Power Plant – Trouble Shooting (Engine Controls)) trouble shooting procedure for aircraft experiencing thrust lever that is unable to move during A/T engagement.

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.21.01.01.04 Indonesia 09.01.2021 Accident Boeing 737-500/ PK-CLC / PT Sriwijaya Air

− If the FMC CDU INTERACTIVE TEST was performed for thrust lever movement problem during the A/T system engagement will result to FWD LOOP or THROT SPLIT fault messages. The subsequent trouble shooting steps would use procedure contained in the AMM chapter 71-00-49 (Power Plant–- Trouble Shooting (Engine Controls)). Similarly, for pilot report of thrust lever split event, the same troubleshooting step should also be in accordance with the procedure in AMM chapter 71-00-49, which contained maintenance steps to check the friction of the engine control cable.

− Therefore, the termination of the trouble shooting after the BITE test result of ‘no faults’ and without the pilot report of thrust lever split, resulted in the engineers stopped the trouble shooting steps and not proceed to examine the engine thrust control as required in AMM chapter 71-00-49. This is likely the reason why the defect prolonged.

Notification/ communication of repetitive defects: − It is likely that line maintenance engineers were not made aware of the recurring A/T problem on this aircraft and have been performing the BITE test to clear the defect. − As such further trouble shooting efforts should be initiated by MCC who has been monitoring for recurring defects under its maintenance management program. − However, the monitoring efforts by MCC did not appear to have raised awareness amongst the line maintenance engineers of the recurring A/T defect and the additional trouble

shooting steps in the “INTERACTIVE TEST” function in the FMC CDU menu. Repetitive defects as hazards to flight safety: − Not addressed in the investigation report (ref. other for SMS). Resolution of the repetitive defects:

− Maintenance records indicated that rectifications performed by line maintenance engineers of similar problem since 2013 were by carrying out a BITE test. After the BITE test result showed ‘no faults’, the engineers stopped the trouble shooting process and signed off the defect without progressing to the steps of carrying out the ‘INTERACTIVE TEST’ in the FMC CDU menu.

− The Sriwijaya Air maintenance management established the MCC which has responsibilities including monitoring the defect and DMI rectification. The progress of DMI rectification was recorded and monitored through DMI control/summary. The DMI control/summary was collected and review by the MCC on daily and weekly basis. MCC should have a process in place to identify and definitively resolve recurring maintenance issues.

− It is evident that the recurring defect monitoring efforts under the maintenance management program has not been implemented effectively given the prolonged unsolved A/T defect on the accident aircraft.

Other: − The investigation received samples of hazard reporting in the period of 2020 which consisted of 565 hazard reports. The evaluation of these data showed that majority of the hazard

were reported by ground personnel. Few hazards were reported by pilots and maintenance personnel and there was no hazard report by dispatchers. This unbalance composition of the hazard reporters is likely an indication that the hazard reporting program has not been emphasized to all employees which could result in hazards not identified and properly mitigated.

− The evidence of low rate of FDAP data analysis, unbalance composition of hazard reporters, and the lack of detail in the hazard identification suggested that Sriwijaya Air safety management system (SMS) has not been implemented effectively.

Proposed mitigating actions for the identified safety gaps

− Promote the importance of fault isolating/ troubleshooting instead of fault clearance − Improve communication CAMO/ AMO/ DAH − Address repetitive defects as hazard to flight safety − Implement automation for fault/ failure reporting to populate the aircraft technical logbook

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Report number State/ Area of occurrence UTC date Occurrence class Aircraft type/ aircraft registration/ operator

KNKT.21.01.01.04 Indonesia 09.01.2021 Accident Boeing 737-500/ PK-CLC / PT Sriwijaya Air

Already existing mitigating actions that may need enhancement

− CAMO repetitive defects management

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9 SIA APPENDIX C - Repetitive defects ECR dashboard (dated 20.09.2023)

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10 SIA APPENDIX D - Delphi study results

Results of the Delphi study (Working Group Members)

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11 SIA APPENDIX E - SenseMaker engagement results

Results of the SenseMaker Engagement (Experiences of Industry Stakeholders)

DEMOGRAPHICS

What is the fleet size of your organisation? (If you are working for an AOC Holder, please share your fleet size with us. Otherwise, you can tick N/A)

90 41

2 54 of A320-232

100 3

7 aircraft. 125 a320 family

23 B787 and 18 B737NG around 150 a/c with mixture of SR & LR

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46 A/C 186x aircraft of A320 Family (A320/320 CEO and NEO) and 1x A330F

1 fleet, 5 aircraft currently worning on Corporate Safety Quality for Lion Air Group

25

PART 1 – DEFINITION, PROCESSES & PROCEDURES

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PART 3 – SHARED EXPERIENCES ON MANAGEMENT OF REPETITIVE DEFECTS

# Please share one of you lived experiences about repetitive defects.This could be an example of 'lessons learned from an incident or near miss' event or it could also be a positive example where a successful outcome was achieved. Ideally this should be a repetitive/recurring defect in a system that may pontetially pose a considerable operational risk to flight safety. In your shared experience differing views and opinions might have been raised by different people involved. i.e. whether to ground the aircraft or raise a 'deferred defect' until the repetitive defect is satisfactorily resolved.

1 We are currently reviewing several repetitive defect investigations that might have a common root cause. We are operating uniquely Airbus A320 family aircraft, these cases are linked to this type. One important topic for this common cause is the correct modification status of the aircraft which is primordial for eliminating recurrent fault messages coming from non-approved configuration (example: overpressure valve) or less robust MOD configuration (outflow valve and CPC1&2 for loss of pressurization control). Some reoccurring defects might be eliminated from the repetitive defect category because those are procedural non-compliances but at first attempt, looks to be system defects. Example: smell/smoke issues due to APU bleed oil contamination. The contributing factor is the APU oil servicing but the real root cause is the incorrect shut down procedure of the APU by flight crew/maintenance crew.

2 As an example, i could state a GPS constantly loosing signal. On ground all tests were passed and only in cruise conditions the problem appeared.

3 Actually after bad outcomes, repetitive defects much moret strictly monitoring and especialy pre determine MEL ıtems, ıf front engineers recognize that ther is a repetititve ıtem, WE count on the aircraft as an AOG.

4 We had two cases of incorrect clamping of wires, causing smoke in one aircraft.

5 We faced a "flaps disagree" repetitive event in our B737 fleet, during the approach flight phase. This event resulted in an interruption of the flaps movement and a consequent risk to the crew to land with an improper flaps configuration. The difficulty here was that our maintenance staff was not able to reproduce the fault after landing and the checks were always passed. Manufacturer recommendations were followed and the problem seems to be solved. However, this situation caused some worries among the crews for a while.

6 FLAP ISSUE IN 737 FLEET

7 In our Fleet, there was an Airbus A320 experienced an Emergency Descent due to Air Pack Regul 1 and 2 Fault. The Investigation revealed that before the incident there were some repetitive defect regarding Air Pack Regul 1 and just rectified by reset/OPS test only! There was no control regarding that Repetitive Defect from ME due to change of organization effect. Eventually, the problem became a Major failure and resulting to an incident when the other Air pack Regul (no. 2) was failed as well.

8 A320 with FUEL LH XFR VALVE OPEN repetitive ECAM message Followed Troubleshooting Manual TSM 28-15-00-810-819 and LH TANK XFR VALVE 11QP shown in transit. According TSM many components replaced such as ACT 11QP, RELAYS 5QP, 6QP, 13QP, DIDOE MOD 1158VD , FQIC , FLSCU 1&2 , but FAULT persist. Aircraft moved to main base to perform deeper troubleshooting. During last troubleshooting, found wire broken. After repair performed, FAULT disappeared.

9 We found severe corrosion happened on a component due contact between some parts. Contacted the OEM regarding the subject and offered a solution to avoid this corrosion to reproduce. OEM approved and we shared this information with the affected airlines. So far this solution has proved to be effective and no longer have faced severe corrosion that may cause this component to fail on the aircraft

10 Aircraft with repetitive defects on fumes and air conditioning issues

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11 In one case, we got a pressurization issue on an aircraft which ground T/S didn’t find any issue. The engineer pressurized the a/c and neither find any leak in door area. On the next departure, same issue occurs and caused in flight return. Further pressurization test found ducting repurtured in the aircon bay.

12 30 May 2023, PK-SAH Msn 5230 has several reports from flight crew related to Eng 2 EPR always fluctuated inflight in several legs, in the same day, TSM TASK 71-00-00-810-833-A has been followed by replacement of PRV Eng 2. 31 May 2023, problem still exist, Aircraft considered stopped for maintenance action, as per TSM TASK 71- 00-00-810-833-A, replaced SOLENOID-BLEED PRESS REG V CTL, ENG 2 (10HA2) Ref. AMM 36-11-55-000- 001 and Ref. AMM 36-11-55-400-001. REF AMM TASK 36-11-52-790-010. Do the Leak Test of the Bleed Pressure Regulator Valve (4001HA) with the Engine in Operation Result Ok. 01 June 2023, Aircraft back to operation with NO defect related to Eng 2 EPR always fluctuated inflight.

13 Hopefully in our organization, due to our fleet and operation, this kind of incident are recurrents. Also our aircrafts are reviwed by our maintenance staff every few hours.

14 May be related to Cabin Temperature Hot condition during on the ground and in flight, there's so many complaints regarding this case also we have some cases regarding the Air Pack Regulator fault during flight time. Based on the cases that happen in our company, it cases have potential consequence Illness/injury to or crew and passenger also have operational impact to our company for the example flight delay, return to stand, and air turnback.

15 Escape slides packs electrical harness incorrectly routed during installation. Electrical harness routing corresponding to a RH position and LH position respectively depends on its installation in the aircraft (LH or RH passenger doors). Pack-assembly is interchangeable and can be installed on a left or on a right door. Electrical harness must be pulled out from girt assembly halves in the flight direction. Then, after quick plug connection, harness excess must be stowed inside the Velcro strip according AMM instructions and information marked on slides surface The issue was solved with a deep promotion and training to the maintenance staff

16 1. the flight crew writes the defect report clearly and precisely so that it does not become a

misperception 2. engineers have different understanding of the problems encountered, could be due to a lack of

mastery of certain systems. 3. lack of communication with manufacturers or vendors on repetitive problems that have not

been resolved. 4. Inadequate availability of spare parts so that it requires engineers to take other actions to solve

the problem. 5. take the steps that are considered the easiest and fastest in solving the problem, for example by

doing "RESET" and "RERACK"

17 Engineer is lack/weak in analyzing the causes of damage (in the trouble shooting process), or lack/weak in mastering the system, so that in the process of solving the damage recurring problems will be repetitive.

18 Raise a deferred defect until the repetitive defect is satisfactory resolved

19 Repetitive defect with a pressure sensor, which was solved by cleaning the sensor but then some flight hours after the indication became to fluctuate again, so the sensor had to be changed after an AOG and cancellation of flights.

20 The most of the examples are to avoid MEL and AOGs, never to avoid an incident or near.. Last time the repetitive monitoring its following the parts already replaced and were Fail on Fit.. The problems last times are with the parts arrived. Its difficult to follow any repetitive fault if you are not sure about new part already installed,.

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21 We create monthly graphs by plane in which with very basic criteria of the type: if a fault (Pireps+Mareps) is repeated more than 3 times in a given period of time, it is considered a possible repetitive fault. Once the data has been collected, they are classified into 2 groups: those with high repetitiveness (more than 2 or 3 times per week) and low repetitiveness (repeat less than 2 or 3 times per week). In the first case they are usually under the knowledge of the Maintenance or Line Manager and in this case they are already under their control, and then not exposed in the graph. For those of less frequency, they usually go unnoticed and are the ones that are taken to the graph. Their history is investigated (even several months ago) and in general it is usually found that they have been appearing for several months but not detected. All the repetitive failures for said aircraft are noted on the graph. Each fault type in a color with an indication of when each fault occurs and the maintenance action carried out, so that it is known what has not been successful. These charts are published monthly and shared with maintenance staff.

22 I work on an aviation authority. From my experience, many times organizations that have the automatic alerts focus only on the strict definition of Deferred Defects (X reports in Y days) and try to solve that "single" recurring defect based only on these X reports, without going back in time to search for related issues that could help on the analysis. It happened that a component was replaced 5 times in 6 months, but it seemed there were no conexion between them, because apparently, the change solved the problem for several weeks and a new count started. They were treated isolated from the rest. It might not happen in small organization, with few aircraft in the fleet. It usually rings a bell on someone.

23 Good communication about defect symphoms, troubleshooting actions performed between technicians and technical support department. Important keep all technicians informed about previous steps done to avoid repetition When requesting TCH assistance provide as much details possible.

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12 SIA APPENDIX F - Bowtie diagram

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Annex B: Detailed definition of the proposed actions The SIA recommendations in Annex A, section 4.2, were reviewed to confirm their scope. It resulted in slight amendments to improve their description without change to their initial intended objective.

1 RM - Development of guidance material for repetitive defects The discussions within the working group and the results of the Delphi study clearly indicated that not necessarily a very prescriptive definition such as the statements in the TCCA regulations but a guidance on how CAMOs should consider repetitive defects would be beneficial for all stakeholders, incl. identification, coordination AMO, CAMO, and aircraft manufacturer, risk assessment collectively conducted by CAMO and flight operations, etc.

The guidance should highlight that repetitive defects may present hazard to flight safety and should not be solely addressed by reliability programmes. This will be addressed in the context of the ongoing work for the Rulemaking task 0735 “Regular update of the CAW regulation”.

2 MST - Oversight of CAMOs and AMOs to ensure repetitive defects are effectively managed

• What is the objective of the MST?

o The main objective is to focus the CA oversight of CAMOs and AMOs to ensure repetitive defects are effectively managed

o The specific objectives are:

▪ to well document as part of CAMOs SMS the hazards and risks associated with repetitive defects which may impact on flight

▪ Equally, to well document as part of AMOs SMS the hazards and risks associated with the normalisation of failure/ fault clearance

▪ to get coordination procedures between CAMOs and AMOs to address repetitive defects.

▪ to ensure that reporting amongst organisations (e.g. also with Design Approval Holder) is to be stressed out, and implementation reviewed, when addressing repetitive defects.

• What is the benefit of this action on MS compared to an action led by EASA (SPT, EVT, RMT)?

o This is a complementary measure while the regulatory framework is being updated.

o The benefit is to reduce the safety risks linked to SI-9001 by having through the direct relation “Competent Authority / CAMO/ maintenance organisations under CA oversight” a focus over an oversight cycle of 2 years.

o This would not be achieved with other types of actions since for the development of this action the Competent Authorities would need to be in the lead for an effective outcome. Indeed it is related to oversight activities that is managed by Competent Authorities.

• What is the expected amount of work for MS to implement the MST?

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o No additional specific workload, it is part of the oversight programme performed by Competent Authorities. It is expected that this action is limited in time.

• Are we not repeating legal obligations on Member States?

o No. The action’s purpose is not related to legal obligation but rather to providing guidance to Competent Authorities.

• Are we recommending an action that the NAA of a Member States is legally entitled to undertake?

o Yes since there is a legal obligation to perform oversight.

3 SPT - Promotion of good practices on managing repetitive defects There are many organisations which implemented robust processes to manage repetitive defects effectively. Nevertheless, the discussions within the working group and the results of the Delphi study have revealed sometimes contrasting views and practices particularly about whether flight crews should be informed about some of the repetitive defects, whether some repetitive defects should be subject to a collective risk assessment and finally, whether sometimes repetitive defects should be treated as deferred defects or not. It can be argued that the differences in opinion on these topics was due to the context and the surrounding circumstances each organisation operates. Therefore, a safety promotion task which aims to explore these differences and share good and innovative ideas would be beneficial for all the other organisations.

Example of practices:

− Communicating that a fault not confirmed/ not found does not mean that the aircraft is airworthy. A

proper system knowledge and understanding of the defect interpretation, together with an historical

fault check, is primordial.

− Using system resets with caution.

− Recording each equipment/ system reset in the aircraft technical logbook, even when seemingly or

perceived as successful.

− Reporting any defect observed by the flight crew, including those that self-clear.

− Adopting common wording between flight crews and maintenance engineers when recording

failures/ faults or other events in the aircraft technical logbook.

− Using not only the aircraft technical logbook but also aircraft data through digital tools to monitor

and identify repetitions.

− Systematic recording of any troubleshooting manual step performed with results.

− Introducing automation or semi-automation in the reporting of failures and faults based on

monitored systems and computers.

− Developing and implementing risk-based approach and procedures to repetitive defects.

− Developing procedures coordinating the different organisations contributing to the management of

repetitive defects.

− Timely sharing of information related to aircraft defects, and coordination between the competent

authorities for the different domains, e.g., the CAMO competent authority, the Part 145 competent

authority and the state of registry competent authority.

Some activities already took place e.g. at the SAFE360 conference 2024: dedicated panel discussion organized to support the promotion of good practices.

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Annex C: Safety impacts assessment

1 General introduction for Attachements C and D Following the European Commission Better Regulation Guidelines6 and the scope of this impact assessment, it was decided to assess the impacts of each proposed action with the Multi-Criteria Methodology (MCA).

MCA is a method enabling to have per proposed action a score indicating the level of positive or negative impacts. EASA uses scale from -10 (very high negative impacts) to +10 (very high positive impacts) to assess 4 impact assessment criteria in a proportionate manner: safety, environment, social and economic.

The analysis for this BIS focuses on the safety and economic criteria, however social and environment are not relevant for this BIS. The Annex C refers to the safety impacts, while the Annex D refers to the economic impacts.

2 Safety impact methodology The baseline is to start from the Safety Issue Prioritisaton Index (SIPI) score with the objective to assess to which extent the SIPI is expected to be reduced (i.e. safety is expected to be improved). This assessment is performed per proposed action through 4 sub-criteria:

• Level of direct expected impact on the Safety Issue

▪ This criteria is directly related to the residual risk SIPI score component which evaluates the

effectiveness of the current technical, organizational and human factors/human performance

barriers.

• Level of additional safety impacts on other Safety Issues

• Level of outreach of the stakeholders

• Level of enhancement of the monitoring of this Safety Issue

6 https://commission.europa.eu/law/law-making-process/better-regulation/better-regulation-guidelines-and-toolbox_en

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3 Results of the safety impact assessment per subcriteria

4 Subcriteria#1 - Direct expected Safety Impact

12.1 General guidelines This criteria combines 2 dimensions: the level of expected severity of a SI and the expected level of effectiveness of the proposed action. 3 levels of severity are defined:

Table 1 - Severity

Level Consequences

S1 Fatal accident and/or loss of aircraft

S2 Accident with injuries / repairable aircraft

S3 Occurrence without casualties / no damage to the aircraft

For SRM driven BIS, the level of severity is always S1 as the selected SIs for SIA are based on the highest SIPI scores, i.e. potentially safety events which could end with fatalities or loss of the aircraft.

Safety scale for SI-9001 - Inadequate management of repetitive defects SIPI score for the component "residual risk" 3.7

SI category Mitigate - Define

Mitigation actions

Title

Type of EPAS action RMT Comment MST Comment SPT Comment

#01 Direct expected Safety

Impact 5

It will provide clarification on

repetitive defects, identification,

and management thereof (not

limited to reliability programme as

it is today)

5

It will raise the focus of competent

authorities oversight activities to

ensure repetitive defects are

effectively managed. This focus is

expected for the next oversight cycle.

4

It will enable to share good

practices from industry and

regulatory stakeholders on how

repetitive defects are identified,

monitored, resolved, and

documented as a key safety risk,

as part of their SMS.

#02 Additional safety impact

on other Safety Issues 0 No link with other Safety Issues 0 No link with other Safety Issues 0 No link with other Safety Issues

#03 Relevant Domain

Outreach 9.5

CAMOs and CAs are the main

addressees of this action.

Maintenance Organisations

contracted by CAMOs should also

benefit from this GM, as it will

address the interface between

both types of organisations.

6.3

CAs are the main addressee of this

action. CAs will have focussed

oversight questions on this safety

issue. CAMOs and Maintenance

Organisations will be subject to

these audits.

5.8

A specific publication on best

practices regarding maintenance

safety issues will address a wide

scope of stakeholders, including

aircraft operators (i.e. flight crew),

and therefore wider than actions 1

and 2.

#04 Enhancing Monitoring

Capacity 5

The clarification on the definition

of repetitive defects will enable a

better monitoring of the safety

issue by facilitating the

identification, and management

thereof (not limited to reliability

programme as it is today)

8

Through CAs focussed oversight on

this safety issue, the immediate

effect will be to get more feedback

on this safety issue, i.e. improving

the monitoring. CAMOs and

Maintenance Organisations will be

subject to these audits.

2.8

A specific publication on best

practices regarding maintenance

safety issues may support

stakeholders to better monitor this

safety issue.

Oversight of CAMOs and AMOs on the

management of repetitive defects

Good practices on managing repetitive

defects

Action #03Action #02

MEDIUM IMPACT LOW IMPACT

1.8 1.2

1.9 2.5

4.9 3.3

Qualitative statement on the

impact

Expected residual risk SIPI

score (New)

MEDIUM IMPACT

Sub

criteria

Guidance material for repetitive defects

Action #01

1.8

1.9

4.9Impact between -10 and +10

Estimation of the impact of the

action on the residual risk

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4 levels of action effectiveness are defined:

bowtie Effect Description

Prevention left Eliminate Complete elimination of the hazard

Prevention left Prevent Reduction of the likelihood that the hazard will occur

Mitigation right Control

Reduction of the likelihood that the hazard results in an accident

Mitigation right Reduce Damage

Reduction of damage if an accident does occur

The combination of the 2 dimensions provides this template table, starting point of the impac analysis:

Scores S1 –Fatal accident

and/or loss of aircraft

S2 - Accident with injuries /

repairable aicraft

S3 - Occurrence without casualties

/ negligible damage to the

aircraft

Type of Barriers impacted by the safety action Tech,

Org, HF (positive or negative)

10 Eliminate

9

8 Eliminate

7 Prevent

6 Prevent Eliminate

5

4 Control Control Prevent

3

2 Control

1 Reduce Damage

Reduce Damage

Reduce Damage

-10 to 0 Theoretical score, impossible in practice for these sub-criteria

By setting maximum scores depending on the level of severity, this enables to have a common reference for any BIS or Impact Assessment performed at rulemaking stage.

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12.2 Direct expected safety benefits on the proposed actions

Scores S1 –Fatal accident

and/or loss of aircraft

S2 - Accident with

injuries / repairable

aicraft

S3 - Occurrence without

casualties / negligible

damage to the aircraft

Type of Barriers

impacted by the safety

action Tech, Org, HF

(positive or negative)

Comments

10

9

8

7

6

5 2)ORG

It will provide clarification on

repetitive defects, identification, and

management thereof (not limited to

reliability programme as it is today)

4

3

2

1

-10 to 0

Action #01 - RMT - Guidance material for repetitive defects

Theoretical score, impossible in practice for these sub-criteria

Scores S1 –Fatal accident

and/or loss of aircraft

S2 - Accident with

injuries / repairable

aicraft

S3 - Occurrence without

casualties / negligible

damage to the aircraft

Type of Barriers

impacted by the safety

action Tech, Org, HF

(positive or negative)

Comments

10

9

8

7

6

5 2)ORG

It will raise the focus of competent

authorities oversight activities to

ensure repetitive defects are

effectively managed. This focus is

expected for the next oversight cycle.

4

3

2

1

-10 to 0

Action #02 - MST - Oversight of CAMOs and AMOs on the management of repetitive defects

Theoretical score, impossible in practice for these sub-criteria

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5 Subcriteria#2: Additional safety impacts on other Safety Issues The objective of this sub-criteria is to determine the potential positive or negative impact of mitigation actions on other risk portfolios within the EPAS or related Safety Issues: "Does the action have side effects on the other Safety Issues. Positive or Negative?" The SI-9001 Inadequate Management of Repetitive Defects has no connection with other Safety Issues. #3: Therefore this criteria is not relevant for this impact assessment.

Scores S1 –Fatal accident

and/or loss of aircraft

S2 - Accident with

injuries / repairable

aicraft

S3 - Occurrence without

casualties / negligible

damage to the aircraft

Type of Barriers

impacted by the safety

action Tech, Org, HF

(positive or negative)

Comments

10

9

8

7

6

5

4 2)ORG

It will enable to share good practices

from industry and regulatory

stakeholders on how repetitive

defects are identified, monitored,

resolved, and documented as a key

safety risk, as part of their SMS.

3

2

1

-10 to 0 Theoretical score, impossible in practice for these sub-criteria

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6 Subcriteria#3: Relevant Domain Outreach The objective of this sub-criteria is to measure the scope of mitigation actions by addressing the generic question, “To what extent does the action reach the relevant stakeholders impacted by the safety action?”.

Action #01 - RMT - Guidance material for repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from -10 to + 10

Comments

CAMO 10 GM is referring to CAMO requirements

National Competent Authorities 9 GM is not linked to an authority requirement directly

Action #02 - MST - Oversight of CAMOs and AMOs on the management of repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from -10 to + 10

Comments

National Competent Authorities 10 CAs are the main addressee of this action. CAs will have a focussed questions on this safety issue.

CAMO 5 CAMOs will be indirectly subject of the MST through the CA oversight.

Maintenance Organisations 5 MOs will be indirectly subject of the MST through the CA oversight.

CAO 5 CAOs will be indirectly subject of the MST through the CA oversight.

Action #03 - SPT - Good practices on managing repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from -10 to + 10

Comments

CAMO 7 Main addressee of this action

Maintenance Organisations 7 Main addressee of this action

National Competent Authorities 5 Indirect addressee of this action

CAO 5 Indirect addressee of this action

Aircraft Operators (pilots) 5 Indirect addressee of this action

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7 Subcriteria#4: Enhancing Monitoring Capacity The objective of this sub-criteria is to estimate “To what extent the addressees will better (or not) monitor the Safety Issue within the safety action perimeter?".

Action #01 - RMT - Guidance material for repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from -10 to + 10

Comments

National Competent Authorities 5 The clarification on the definition of repetitive defects will enable a better monitoring of the safety issue by facilitating the identification, and management thereof (not limited to reliability programme as it is today)

CAMO 5

Action #02 - MST - Oversight of CAMOs and AMOs on the management of repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from - 10 to + 10

Comments

National Competent Authorities 8

Through CAs focussed oversight on this safety issue, the immediate effect will be to get more feedback on this safety issue, i.e. improving the monitoring. CAMOs and Maintenance Organisations will be subject to these audits.

CAMO 3 Through CAs focussed oversight on this safety issue, the immediate effect will be to get more feedback on this safety issue, i.e. improving the monitoring. CAMOs and Maintenance Organisations being subject to these audits will also pay more attention to this safety issue, and as a side effect it will improve the monitoring

Maintenance Organisations 3

Action #03 - SPT - Good practices on managing repetitive defects

Direct stakeholders outreached by the mitigation action

Estimated impact from - 10 to + 10

Comments

National Competent Authorities 4

A specific publication on best practices regarding maintenance safety issues may support stakeholders to better monitor this safety issue.

CAMO 4

Maintenance Organisations 2

CAO 2

Aircraft Operators (pilots) 2

European Union Aviation Safety Agency – EPAS 2024 – 2026

Best Intervention Strategy with Safety Issue Assessment SI-9001 - Inadequate management of repetitive defects

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Annex D: Economic impacts assessment As per information provided in the Annex C, section 1, the following table provides the assessment of the economic impacts of the proposed actions.

1 General guidelines On EASA resources, the following analysis was conducted. For Action 3, the workload for the safety promotion task was assessed according this baseline:

Types of Safety Promotion deliverables

Standard SPT Baseline for resources

SPT team hours SPT mission budget SPT procurement budget Campaign (several events, videos, publications, …) 320 5000 50000 Package (several publications grouped) 80 1500 5000 Publication (e.g. only one short information like a webpage publication on EASA website) 16 0 500 Annual total resources in average for the SPT activity

1 FTE (1600 hours) for a specific topic 30000 225 000€

On top of these resources, the different directorates may need to provide specific inputs for the content of the safety promotion material. An additional workload is also to be estimated based on the consideration that the CT Directorate provides an average annual volume of 2400 hours for safety promotion tasks and FS Directorate provides 4000 hours. These impacts are measured with a scale from -10 to +10 looking at the resource intensity usage by using this a non-linear scale:

Scale Score Share of resources used with a linear scale

Share of resources used with a non-linear scale

Very high 10 100.0% 100.0% 9 90.0% 80.0% 8 80.0% 60.0% High 7 70.0% 40.0% 6 60.0% 30.0% Medium 5 50.0% 20.0% 4 30.0% 15.0% 3 30.0% 10.0% Low 2 20.0% 5.0% 1 10.0% 1.0% Negligible 0 0.0% 0.0%

European Union Aviation Safety Agency – EPAS 2024 – 2026

Best Intervention Strategy with Safety Issue Assessment SI-9001 - Inadequate management of repetitive defects

TE.RPRO.00400-006© European Union Aviation Safety Agency. All rights reserved. ISO 9001 certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA intranet/internet. Page 84 of 86

An agency of the European Union

Principle behind this non-linear progression of the weights: Due to the current Agency resources issues, it is important to capture that any additional resource has a significant impact. For instance, with a linear scale, an increase of 10% of the workload would get a score 1 of 10, meaning very low negative impact. But with a non-linear scale attributing more importance to this 10% of increase, the workload would get a score 3 out of 10, meaning already a medium negative impact.

Draft Actions 1 to 3 are assessed in the sections 7.2 and 7.3.

2 Implementation on the draft RMT and MST actions Draft RMT: The RMT with 1 to 2 weeks of work on development the technical content has a negligible on the EASA resources. Regarding stakeholders, the GM may create very minor additional work with its implementation in the CAMOs and MOs. This will be compensated by potential higher benefits than the workload impacts by creating efficiency instead remaining with an inefficient management of repetitive defect. Draft MST Each oversight cycle has his own focus. There is indeed a part of the preparation of any regular oversight to focus on a specific issue. By focusing on repetitive defects in the next oversight cycle, this will not add any additional hours compared to the standard work as well from Competent Authority side than on Maintenance stakeholders side.

European Union Aviation Safety Agency – EPAS 2024 – 2026

Best Intervention Strategy with Safety Issue Assessment SI-9001 - Inadequate management of repetitive defects

TE.RPRO.00400-006© European Union Aviation Safety Agency. All rights reserved. ISO 9001 certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA intranet/internet. Page 85 of 86

An agency of the European Union

Summary table for draft RMT and MST actions:

3 Implementation on the draft SPT action The SPT actions belonged to these standard SPT deliverables:

Type of SPT per Action for the SI-9001 Types of Safety Promotion deliverables Action 3 - Good practices on managing repetitive defects

Publication (e.g. only one short information like a webpage publication on EASA website)

European Union Aviation Safety Agency – EPAS 2024 – 2026

Best Intervention Strategy with Safety Issue Assessment SI-9001 - Inadequate management of repetitive defects

TE.RPRO.00400-006© European Union Aviation Safety Agency. All rights reserved. ISO 9001 certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA intranet/internet. Page 86 of 86

An agency of the European Union

Impact on SPT resources:

The average per action of the above scores provide this overall impact:

Action 1

Good practices on managing

repetitive defects

SPT Publication

-0.8

LOW IMPACT