# Annex 13 Essential Definitions: Accident, Incident, and Serious Incident

> Learn Annex 13 definitions that distinguish accident, incident, and serious incident, including practical examples and structural-damage exceptions.

- **Subject:** 010 — Air Law
- **Section:** 010-13 — Aircraft Accident and Incident Investigation
- **Topic code:** 010-13-01
- **Last reviewed:** 2026-03-27
- **Author:** Pablo Asensio Martínez
- **HTML version:** https://pilotsyllabus.com/en/air-law/aircraft-accident-and-incident-investigation/essential-definitions-of-icao-annex-13/

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## Accident
An occurrence associated with the operation of an aircraft (from boarding with the intention of flight until disembarking) in which:
1.  A person suffers **fatal or serious injury**.
2.  The aircraft sustains **damage or structural failure** which adversely affects the structural strength, performance or flight characteristics and would normally require major repair.
3.  The aircraft is missing or remains completely inaccessible.

> **Exceptions for damage:** Engine failure or damage limited to a single engine, propellers, wing tips, antennas, tyres, brakes, or small dents in the skin. These do **not** classify as an accident by themselves.

## Incident
An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.

## Serious Incident
An incident involving circumstances indicating that there was a **high probability** of an accident.
*   The difference between an accident and a serious incident lies only in the **result**.

**Examples of Serious Incidents:**
*   **Near collision** requiring an avoidance manoeuvre.
*   Controlled flight into terrain (**CFIT**) only marginally avoided.
*   Take-off or landing on a closed or engaged runway.
*   Fire/Smoke in the cockpit or cargo compartment.
*   **Flight crew incapacitation**.
*   Fuel emergency requiring the declaration of distress.

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