Guidance

Definition of Aircraft Accident and Serious Incident

Published 4 December 2004

1. Definition of an Accident

“Accident” means an occurrence associated with the operation of an aircraft which, in the case of a manned aircraft, takes place between the time any person boards the aircraft with the intention of flight and such time as all such persons have disembarked, or in the case of an unmanned aircraft, takes place between the time the aircraft is ready to move with the purpose of flight until such time it comes to rest at the end of the flight and the primary propulsion system is shut down, in which:

  1. a person is fatally or seriously injured as a result of:
    • being in the aircraft
    • direct contact with any part of the aircraft, including parts which have become detached from the aircraft
    • direct exposure to jet blast, except when the injuries are from natural causes, self-inflicted or inflicted by other persons, or when the injuries are to stowaways hiding outside the areas normally available to the passengers and crew
  2. the aircraft sustains damage or structural failure which adversely affects the structural strength, performance or flight characteristics of the aircraft, and would normally require major repair or replacement of the affected component, except for engine failure or damage, when the damage is limited to a single engine, (including its cowlings or accessories), to propellers, wing tips, antennas, probes, vanes, tires, brakes, wheels, fairings, panels, landing gear doors, windscreens, the aircraft skin (such as small dents or puncture holes) or minor damages to main rotor blades, tail rotor blades, landing gear, and those resulting from hail or bird strike, (including holes in the radome)

  3. the aircraft is missing or is completely inaccessible.

1.1 Definition of serious injury

“Serious injury” means an injury which is sustained by a person in an accident and which involves one of the following:

  1. hospitalisation for more than 48 hours, commencing within 7 days from the date the injury was received;
  2. a fracture of any bone (except simple fractures of fingers, toes, or nose);
  3. lacerations which cause haemorrhage, nerve, muscle or tendon damage;
  4. injury to any internal organ;
  5. second or third degree burns, or any burns affecting more than 5% of the body surface;
  6. verified exposure to infectious substances or harmful radiation.

2. Definition of a Serious Incident

“Serious Incident” means an incident involving circumstances indicating that there was a high probability of an accident and is associated with the operation of an aircraft, which in the case of a manned aircraft, takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, or in the case of an unmanned aircraft, takes place between the time the aircraft is ready to move with the purpose of flight until such time it comes to rest at the end of the flight and the primary propulsion system is shut down.

The incidents listed below are typical examples of serious incidents. The list is not exhaustive and only serves as a guide to the definition of ‘serious incident’.

  • A near collision requiring an avoidance manoeuvre or when an avoiding manoeuvre would have been appropriate to avoid a collision or an unsafe situation.
  • Controlled flight into terrain (CFIT) only marginally avoided.
  • An aborted takeoff or a takeoff using a closed or engaged runway, a taxiway or unassigned runway.
  • A landing or attempted landing on a closed or engaged runway, a taxiway or unassigned runway.
  • Gross failure to achieve predicted performance during takeoff or initial climb.
  • All fires and/or smoke in the cockpit, in the passenger compartment, in cargo compartments or engine fires, even though such fires were extinguished with extinguishing agents.
  • Any events which require the emergency use of oxygen by the flight crew.
  • Aircraft structural failure or engine disintegration, including uncontained turbine engine failure, which is not classified as an accident.
  • Multiple malfunctions of one or more aircraft systems that seriously affect the operation of the aircraft.
  • Any case of flight crew incapacitation in flight.
  • Any fuel state which would require the declaration of an emergency by the pilot.
  • Runway incursions classified with severity A. The ‘Manual on the Prevention of Runway Incursions’ (Doc 9870) contains information on the severity classifications.
  • Takeoff or landing incidents, such as undershooting, overrunning or running off the side of runways.
  • System failures, weather phenomena, operation outside the approved flight envelope or other occurrences which caused or could have caused difficulties controlling the aircraft.
  • Failure of more than one system in a redundancy system which is mandatory for flight guidance and navigation.
  • The unintentional or, as an emergency measure, the intentional release of a slung load or any other load carried external to the aircraft.

3. Find out how to report an aircraft accident or serious incident

You can find guidance on how to report an accident or serious incident on our Report an aircraft accident or serious incident page.

For further information contact the AAIB:

Air Accidents Investigation Branch
Farnborough House
Berkshire Copse Road
Aldershot
Hampshire
GU11 2HH

Tel: 01252 510300
Fax: 01252 376999
Email: <enquiries@aaib.gov.uk>