Definition
A malfunction or breakdown of a physical aircraft component or system — such as the engine, landing gear, flight controls, hydraulics, or electrical system — that prevents it from operating as designed. In emergency procedure context, mechanical failure is one of the recognized abnormal conditions that may require the pilot to declare an emergency, deviate from a clearance, or execute a non-standard procedure to ensure safe flight and landing.
Plain English
Something on the aircraft has broken or stopped working the way it should, and the pilot has to deal with it.
Context Anchor
Seen in emergency and abnormal-procedure discussions when an aircraft part, control, engine, gauge, or system stops working correctly.
Derivation
From Latin mechanicus (relating to machines) and Latin fallere (to fail or deceive). Together, the phrase simply means a machine part has stopped doing its job. Knowing this helps separate it from other emergency types like medical issues or weather problems — mechanical failure is specifically about the aircraft's hardware.
Why Pilots Care
Prompt recognition allows the pilot to apply the correct checklist and maintain control until a safe landing can be made.
Intuition Check
Do not assume mechanical failure means only an engine failure. In aviation, it can mean any physical aircraft part or system that stops working correctly.
Example Sentence 1
After the landing gear failed to retract, the pilot reported a mechanical failure to ATC and requested a return to the departure airport.
Example Sentence 2
During the approach, a mechanical failure in the vacuum system required an immediate transition to partial panel instruments.