Method for Computing
Airliner Fatal Event Rates

The following provides details and the data and the basic method used by to calculate fatal event rates of airlines and aircraft types.

FLE - Full Loss Equivalent: This is the sum of the proportions of passengers killed for each fatal event. For example, 50 out of 100 passengers killed on a flight is an FLE of 0.50, 1 of 100 would be a FLE of 0.01. The fatal event rate for a set of fatal events is found by dividing the total FLE by the number of flights in millions.

Fatal Event: Any circumstance where one or more passengers on an aircraft flight die from causes that are directly related to the operation of that aircraft. The fatal event may be due to an accident or due to a deliberate act by another passenger, a crew member, or by one or more persons not on the aircraft. These events include sabotage, hijacking, or military action and exclude cases where the only passenger deaths were to hijackers, saboteurs, or stowaways.

Note that the fatal event rates associated with an airline or aircraft model does not constitute either an endorsement or a lack of an endorsement of any particular airline aircraft model. These rates are also an estimate of historical risk rather than an estimate or prediction of future performance.

Passenger Flight: A scheduled or unscheduled flight on an aircraft that is operated by an airline where the general public has an opportunity to be a passenger.

Included Fatal Events: An event was included with a specific airline or airline grouping if the event was associated with a flight operated by the airline or in association with another airline. An associated airline flight includes flights by subsidiaries of an airline or flights performed on behalf of an airline by another airline.

Determining the Fatal Event Rate: The sum of the full loss equivalent (FLE) events is divided by the estimated number of flights to determine the estimated fatal event rate. For more information on this method, please refer to issue 15 of the AirSafe Journal.

Advantages: This method is used because it is easy to calculate and is independent of either the length or the duration of the flight. It is based on the Q-statistic of Barnett and Wang [1] which is the mortality risk of a passenger for a randomly chosen flight.

Other Definitions: On many fatal event tables, M means a million, so a figure like 0.44M in the flights column refers to 0.44 million flights or 440,000 flights.

Data Sources: Sources of fatal event and airline flight data include Flight International, Conde Nast Traveler, the New York Times, ICAO, and the U.S. National Transportation Safety Board.

[1] Barnett, A. and Wang A.; Passenger Mortality Risk Estimates Provide Estimates about Airline Safety, Flight Safety Digest, April 2000, p. 1-12, Flight Safety Foundation.

Definitions of other key terms Method for Computing Airliner Fatal Event Rates -- Revised: 10 November 2015