Plain English Meaning

Something on the airplane stops working properly. It might quit altogether, or it might still work but not the way it should.

Full Definition

Failures or abnormal behavior of an aircraft system, instrument, or component that prevents it from operating as designed. Malfunctions can be partial (a system performing poorly or intermittently) or complete (a system failing entirely), and they may involve engines, flight controls, electrical systems, avionics, landing gear, or any other installed equipment.

Context Anchor

A pilot may encounter equipment malfunctions during preflight, engine run-up, flight, landing, or while following emergency procedures.