ICAO Annexes: the operational framework of international civil aviation
ICAO, established under the Convention on International Civil Aviation 1944 (“Chicago Convention”), occupies a central position in the international civil aviation regulatory and safety framework. Its reach is near‑universal among the world's states. ICAO’s authority is exercised principally through the adoption of Standards and Recommended Practices (“SARPs”), set out in nineteen Annexes to the Convention. [1]
The Annexes give practical effect to the principles of the Chicago Convention. Together they regulate a broad range of technical, operational, safety and security matters, including personnel licensing, aircraft operations, air navigation services, security and accident investigation. Standards are binding on Contracting States, subject to notification of differences pursuant to Article 38 of the Convention; Recommended Practices are advisory, but reflect internationally accepted norms of safety, regularity and efficiency. Collectively, ICAO administers approximately 12,000 SARPs across its nineteen Annexes.[2]
Annex 13 – evolving through learning
Annex 13 (Aircraft Accident and Incident Investigation), first published in 1951 and now in its thirteenth edition (2024), occupies a unique position among ICAO's Annexes. Unlike those governing ongoing airworthiness or operational compliance, Annex 13 addresses what occurs after a serious accident or incident: how investigations are conducted, how investigative independence is preserved, and—critically—how air accident investigation findings are reported and disseminated to national and wider global aviation communities.
Publication as a legal obligation under Annex 13
Central to Annex 13 is the requirement for the state conducting an accident or serious incident investigation—commonly, though not invariably, the State of Occurrence—to publish a final report as soon as possible and, where practicable, within twelve months. Where that timeframe cannot be met, recurring interim statements setting out progress and any identified safety issues are required.
These requirements are ICAO Standards, not Recommended Practices. They give effect to Article 26 of the Chicago Convention, which obliges states to institute an inquiry into the circumstances of an accident and to communicate its findings. Publication is therefore not optional; it is part of the investigation itself.
Publication: why it matters
The foundation of Annex 13 investigation reports is accident and incident prevention. Annex 13 makes this explicit. Chapter 3 (General, paragraph 3.1) provides that, "the sole objective of the investigation of an accident or incident shall be the prevention of accidents and incidents. It is not the purpose of this activity to apportion blame or liability." Investigation reports provide an authoritative account of what occurred and why. They set out the factual sequence of events, and where they arise, identify technical failures, operational decisions, environmental conditions and other contributory factors. Conclusions as to accident cause are reached and safety recommendations, directed at preventing recurrence, are made.
From an insurance perspective, final reports support informed loss analysis and claims assessment, recovery prospects, subrogation and contribution, as well as reserving decisions. Where final reports are materially delayed or absent, uncertainty persists across policy years and claims resolution following major loss is prolonged.
Non‑compliance: a growing pattern of concern
ICAO has increasingly recognised that delays and/or failures to publish final reports are not isolated issues but reflect a developing pattern of concern. Between 2018 and 2023, IATA data indicates that of 269 accidents classified by the IATA Accident Classification Task Force, only 57 per cent resulted in a published final report. A significant number of investigations remain open-ended, with interim statements either absent or substantively repetitive.[3]
Key aviation industry bodies have voiced their concerns to ICAO, to include IATA (International Air Transport Association), IFALPA (International Federation of Air Line Pilots’ Associations), IFATCA (International Federation of Air Traffic Controllers’ Associations), FSF (Flight Safety Foundation) and organisations representing injured passengers and bereaved families (to include the Air Crash Victims’ Families’ Federation International (ACVFFI)). Voiced concerns are encapsulated in the following statement:
"A strong commitment to transparency and the continuous improvement of aviation safety requires that States ensure the complete, timely, and accessible publication of investigation reports. Reinforcing this standard and its compliance is essential to the credibility of the international safety system, institutional learning, and the respect owed to victims and their families."[4]
Reasons for delay or non‑publication
Several recurring factors explain delay or non‑publication of final air accident reports:
- Parallel criminal or judicial proceedings remain the most common source of delay. In some states, criminal investigations are treated as overriding Annex 13 obligations, leading to suspension of safety investigations, restricted access to evidence or deferral of publication until related criminal proceedings conclude.
- National security and unlawful interference considerations also feature prominently. Accidents occurring in conflict zones, involving suspected hostile acts or touching upon intelligence or defence matters are frequently accompanied by restrictions on disclosure. Such cases account for a disproportionate share of investigations that never culminate in a full, public report.
- Conflicts of interest within the State of Occurrence present further difficulties. Where State bodies are implicated—as operators, regulators, air navigation service providers or security authorities—concerns about institutional independence can slow investigative progress or constrain the scope of inquiry. In states lacking a functionally or legally independent accident investigation authority, these pressures may result in delayed inquiries or reports falling short of the standards set out in ICAO Annex 13.
- Resource constraints may also contribute. Accident investigation requires specialist expertise and analytical capability. For example, this can embrace metallurgical and fracture examination, fire and explosion modelling, and fatigue and corrosion assessment. Where investigative bodies are under‑resourced or rely on external technical assistance, reporting timelines may extend well beyond Annex 13 expectations.
- Where responsibility for investigation is divided between separate authorities, progress may be slower, accountability less clear, and publication of findings more readily deferred or disputed.
- Finally, in high‑profile accidents, political or reputational considerations may, in practice, lead states to mitigate reputational and political exposure by slowing publication or relying on interim statements that provide minimal, meaningful detail. Historically, limited enforcement action under Annex 13 has enabled such practices to persist.
Taken together, these factors explain why delayed or non‑publication has evolved into a recurring issue. In many cases delay reflects not technical complexity alone, but unresolved tensions between safety investigation, sovereignty, criminal justice processes and political accountability. From an aviation insurance perspective, these are often the very cases giving rise to complex, high‑value losses.
ICAO’s response: Amendment 20 to Annex 13
At its 237th Council Session in March 2026, ICAO adopted Amendment 20 to Annex 13. ICAO expressly acknowledged that recent investigations had been halted, compromised or transferred in ways that resulted in prolonged delay or the absence of a final report, and that this position was no longer acceptable.[5]
The amendment does not introduce sanctions. Instead, it narrows the scope for delay or non‑publication by clarifying responsibilities, reinforcing investigative independence and addressing evidential and reporting barriers.
Amendment 20 has been circulated to Contracting States by ICAO State Letter. A consolidated edition of Annex 13 incorporating the amendment has not yet been published. Accordingly, current analysis of the amendment necessarily relies on ICAO explanatory material and on Council Decision (EU) 2026/714 of 17 March 2026, which sets out the European Union’s position on adoption. While that Decision does not reproduce the amended text, it describes the purpose, scope and legal effects of the amendment with sufficient clarity [6]. The principal features of Amendment 20 include:
- Reaffirmation of State of Occurrence responsibility: Amendment 20 re‑affirms responsibility squarely with the State of Occurrence. It clarifies, in unequivocal terms, that the obligation imposed by Annex 13 is not simply to initiate an investigation, but to institute, conduct, complete and publish it. Investigations are no longer to be treated as open‑ended processes that can lapse into inertia. The purpose of this clarification is explicit: to prevent investigations being prematurely terminated, indefinitely paused, or concluded in substance but never brought to publication by the stalling of a final report.
- Explicit treatment of conflicts of interest: For the first time, Annex 13 confronts conflicts of interest directly and explicitly. Amendment 20 acknowledges that such situations do arise and that, where they do, continued investigation by the State of Occurrence may undermine confidence in the process and its outcomes. Formal delegation—whether to another state or to a regional investigation body—is therefore reframed as a legitimate and necessary tool to preserve credibility. This represents a substantive shift. Delegation was previously permitted but loosely framed. Crucially, because delegation is now explicitly tied to the continuing duty to complete and publish a final report, it can no longer be used—expressly or by default—as a means of distancing the State of Occurrence from accountability or explaining non‑compliance.
- Strengthening evidential access: Amendment 20 removes language that had, in practice, been relied upon to justify delayed, restricted or qualified disclosure of accident evidence. In its place, Amendment 20 makes clear that accident investigation authorities must be afforded unrestricted and timely access to all relevant evidential material. This change is directed squarely at scenarios in which access to wreckage, recordings, data or witness material has been subject to judicial, security or administrative controls, with consequential delay or erosion of investigative findings.
- Independence from criminal proceedings: Amendment 20 reinforces the principle that the existence of criminal or other judicial investigation does not justify suspension of the Annex 13 investigation nor the non‑publication of a final report. Safety investigation is no longer to be treated as contingent upon the resolution of other legal processes. Where such proceedings exist, they must be managed alongside—not in substitution for—the obligation to complete and publish the safety investigation in accordance with Annex 13.
Most substantive Amendment 20 changes will come into force from November 2028. In the intervening period, ICAO is to provide updated manuals and regional workshops, where needed, to help member states implement these changes into national law by the 2028 deadline. Taken as a whole, the significance of Amendment 20 lies in tightening expectations and narrowing the discretion historically relied upon to justify delay or non‑publication.
Conclusion: a change in expectations
Amendment 20 does not convert Annex 13 into an enforcement regime. It does, however, reflect a change in expectations. Prolonged silence following an air accident is no longer viewed merely as an unfortunate consequence of investigative process, but as a factor liable to undermine confidence in the international aviation safety framework.
It is perhaps interesting to examine the stance of the Air Accidents Investigation Branch (AAIB), the UK government investigator of aviation incidents and accidents. In their 2024 Annual Safety Review, they provided an overview of investigation status – noting that in a single calendar year they initiated 20 filed investigations, 57 correspondence investigations and supported 53 new overseas investigations which involved UK interests in some way. In the same year, the AAIB published 36 field investigations, a further 65 conducted by correspondence, and 160 described as "record-only investigations"[7].
On its website, the AAIB keeps a running record of its "current field investigations". At the time of writing there are more than 25 ongoing investigations and it is worth noting that the oldest of these dates back to June 2022.
For aviation insurers and claims handlers, the absence of a final report does not extinguish liability. Instead, it prolongs uncertainty, delays resolution and increases cost. For these reasons, publication remains indispensable to effective legal and insurance outcomes. Silence preserves uncertainty; investigation exists to resolve it.
[1] Convention on International Civil Aviation, signed at Chicago on 7 December 1944, 15 UNTS 295
[2] ICAO : https://www.icao.int/how-icao-develops-standards
[3] The IATA Accident Classification Task Force (ACTF) is an IATA body that develops and maintains a standardised global framework for classifying aviation accidents and serious incidents to ensure consistency in safety data, analysis, and reporting across the industry.
[4] International Civil Aviation Organization (ICAO), Publication of Final Accident Investigation Reports, Working Paper A42‑WP/43, 42nd ICAO Assembly, presented by Air Crash Victims’ Families’ Federation International (ACVFFI), 14 July 2025.
[5] ICAO newsroom press release, 27 March 2026 "ICAO strengthens global framework for accident investigations, addresses conflicts of interest".
[6] Council Decision (EU) 2026/714 of 17 March 2026 on the position to be taken on behalf of the European Union at the 237th session of the Council of the International Civil Aviation Organization (ICAO) as regards the adoption of the amendment to Annex 13 to the Convention on International Civil Aviation, OJ L 714, 20.3.2026.
[7] Air Accidents Investigation Branch, Annual Safety Review 2024 (Department for Transport, published 12 June 2025).
