If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user


Occurrence Category Taxonomy

From SKYbrary Wiki

(Redirected from Occurrence Category Taxonomy)
Article Information
Content source: ICAO ICAO
Content control: ICAO ICAO


The ADREP Occurrence category taxonomy is a set of terms used by ICAO to categorize aircraft accidents and incidents and allow safety trend analysis on these categories. The ADREP Occurrence category taxonomy is part of the ICAO accident reporting system (ADREP).


The terms of this taxonomy are grouped into primary and secondary terms. Every occurrence should have attached a single primary occurrence category but may be attached in addition multiple secondary terms. For accidents, the primary term can be considered as the end state in comparison with the IATA taxonomy.

ADREP occurrence category taxonomy terms
Primary (15)
Term Acronym
Abnormal runway contact ARC
Birdstrike BIRD
Controlled flight into or toward terrain CFIT
Collision with obstacle(s) during take-off and landing CTOL
Fire/smoke (non-impact) F-NI
Ground Collision GCOL
Loss of control - inflight LOC-I
Airprox/ ACAS alert/ loss of separation/ (near) midair collisions MAC
Ground Handling RAMP
Runway excursion RE
Runway - wildlife presence RI-A
Runway incursion - vehicle, aircraft or person RI-VAP
System/component failure or malfunction [non-powerplant] SCF-NP
Powerplant failure or malfunction SCF-PP
Undershoot/overshoot USOS
Secondary (18)
Loss of control - ground LOC-G
Turbulence encounter TURB
Fuel related Fuel
Aerodrome ADRM
Low altitude operations LALT
Fire/smoke (post-impact) F-POST
Windshear or thunderstorm WSTRW
Icing ICE
Evacuation EVAC
Security related SEC
Cabin safety events CABIN
Abrupt manoeuvre AMAN
Loss of lifting conditions en-route LOLI
Unintended flight in IMC UIMC
Glider towing related events GTOW
External load related occurrences EXTL
Unknown or undetermined UNK


There are currently no rules set within this taxonomy or in relation with other ADREP taxonomies.
However, by the end of 2010 and following an analysis of the current ADREP data, ICAO may add rules to make the primary occurrence category mandatory and unique for occurences where the occurrence class is "accident".

Related Articles

Further Reading