The Dispatch Reliability (DR) (English about Dispatch reliability or dispatch reliability ) describes the technical availability of an aircraft before takeoff. It indicates the probability with which an aircraft can take off without an aborted take-off or a long delay (internationally a maximum of 15 minutes is expected).
Dispatch reliability is calculated from the ratio of the number of scheduled take-offs (with a maximum of 15 minutes delay) to the number of all scheduled take-offs (including canceled flights). Unplanned irregularities that are not due to technical reasons are not taken into account.
Dispatch reliability is specified for aircraft types as well as for airlines or maintenance companies.
When calculating the dispatch reliability of aircraft types, all starts of aircraft of this type are evaluated over a certain period of time. While in 1976 a DR of around 90% was given for the Concorde (based on 255 flights), today the values are over 99%. For mature aircraft (that is, as much as fully developed aircraft ), a DR of over 99.8% is expected.
When calculating the dispatch reliability of airlines and maintenance companies, all machine starts of this company are also taken into account for a certain period of time. In a table published by the maintenance company of Futura in 2005, DR values between 96.4% and 100% are given for 30 companies.