Suicide by pilot is an aviation event in which a pilot deliberately crashes or attempts to crash an aircraft as a suicide act, with or without the intention of causing harm to passengers on board or people on the ground. If others are killed, it may be considered a type of murder–suicide. It is suspected to have been a possible cause in several commercial flight crashes and has been confirmed as the cause in other instances. Determining the motives of pilots can be challenging for crash investigators, as pilots may intentionally disable recording devices or engage in other actions to impede future investigations. Consequently, definitively proving pilot suicide can be difficult.

An aviation accident is defined by the Convention on International Civil Aviation Annex 13 as an occurrence associated with the operation of an aircraft, which takes place from the time any person boards the aircraft with the intention of flight until all such persons have disembarked, and in which (a) a person is fatally or seriously injured, (b) the aircraft sustains significant damage or structural failure, or (c) the aircraft goes missing or becomes completely inaccessible. Annex 13 defines an aviation incident as an occurrence, other than an accident, associated with the operation of an aircraft that affects or could affect the safety of operation.