Calculated accident and incident rates — the number of accidents or incidents during a given period divided by some measure of exposure, such as number of flights, over that period — is a basic tool used to measure and report safety performance in commercial aviation. But aviation regulators, trade organisations and other stakeholders can have varying definitions and accident classifications and often measure different but overlapping segments of the industry.
In 2010, the European Commission, the U.S. Department of Transportation, the International Civil Aviation Organisation (ICAO) and the International Air Transport Association (IATA) signed an agreement to develop a Global Safety Information Exchange (GSIE). The objective of the GSIE is to identify information that can be exchanged among the parties to enhance risk-reduction activities. At the time, ICAO said the GSIE was formed to help reduce the risk of accidents and improve the overall level of aviation safety worldwide.
In 2011, GSIE began work on developing a harmonised accident rate. ICAO and IATA worked to align accident definitions, criteria and analysis methods used to calculate the harmonised rate, which is considered a key safety indicator for commercial aviation operations.
The analysis includes accidents meeting the ICAO Annex 13 criteria for all typical commercial airline operations for scheduled and nonscheduled flights. The GSIE harmonised accident rate is measured in accidents per million sectors and includes scheduled and nonscheduled commercial operations, including ferry flights with a maximum takeoff weight (MTOW) of more than 5,700 kg. ICAO and IATA worked to develop a common taxonomy that would allow integration of accident data between the two organisations.
The GSIE harmonised accident categories are as follows:
- Controlled flight into terrain (CFIT) — Includes all instances in which the aircraft was flown into terrain in a controlled manner, regardless of the crew’s situational awareness. Does not include undershoots, overshoots or collisions with obstacles on takeoff and landing, which are included in the runway safety category.
- Loss of control–in flight (LOC-I) — Loss of control in flight that is not recovered.
- Runway safety (RS) — Includes runway excursions, incursions, undershoot/overshoot, tail strike and hard landing events.
- Ground safety (GS) — Includes ramp safety, ground collisions, all ground servicing, preflight, engine start/departure and arrival events. Taxi and towing events are also included.
- Operational damage (OD) — Damage sustained by the aircraft while operating under its own power. Includes in-flight damage, foreign object debris and all system or component failures.
- Injuries to and/or incapacitation of persons (MED) — All injuries or incapacitations sustained by anyone coming in direct contact with any part of the aircraft structure. Includes turbulence-related injuries; injuries to ground staff coming in contact with the structure, engines or control surfaces of the aircraft and on-board injuries or incapacitations; and fatalities not related to unlawful external interference.
- Other (OTH) — Any event that does not fall into one of the categories listed above.
- Unknown (UNK) — Any event in which the exact cause cannot be reasonably determined through information or inference, or in which there are insufficient facts to make a conclusive decision regarding classification.