The ADREP Occurrence class taxonomy is a set of terms used by ICAO to categorize occurrences by severity and allow safety trend analysis on these categories. The ADREP Occurrence class taxonomy is part of the ICAO accident data reporting system (ADREP).
"An occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which:
a) a person is fatally or seriously injured as a result of:
- being in the aircraft, or
- direct contact with any part of the aircraft, including parts which have become detached from the aircraft, or
- 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;
b) 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 the engine, its cowlings or accessories;
- or for damage limited to propellers, wing tips, antennas, tires, brakes, fairings, small dents or puncture holes in the aircraft skin;
c) the aircraft is missing or is completely inaccessible."
"An incident involving circumstances indicating that an accident nearly occurred.
N.B. Examples of serious incidents can be found in Attachment D of ICAO Annex 13 and in the ICAO Accident/Incident Reporting Manual (ICAO Doc 9156)."
"An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.
N.B. The type of incidents which are of main interest to the International Civil Aviation Organization for accident prevention studies are listed in the ICAO Accident/Incident Reporting Manual (ICAO Doc 9156) and ICAO Annex 13."
Occurrence without safety effect
"Eurocontrol: An incident which has no safety significance.
N.B. This appears to be a contradiction with the ICAO definition of an incident: An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.
A possibly safety related occurrence not meeting the reporting requirements. This could be e.g. the result of downgrading the incident after review.
The class of the occurrence has not been determined.