Definition
A condition in which one or more of the airplane's primary or secondary flight controls fails to operate normally, operates only partially, jams, disconnects, or responds incorrectly to pilot input. This includes problems with the ailerons, elevator, rudder, trim systems, flaps, or the cables, pushrods, hydraulic actuators, and electrical systems that move them.
Plain English
Something has gone wrong with the parts of the airplane that let the pilot steer it. A control might be stuck, broken, disconnected, or only working part way, so the airplane doesn't respond normally to stick, yoke, rudder pedal, or trim inputs.
Context Anchor
Encountered in emergency procedures, abnormal flight situations, preflight control checks, and FAA training on how to keep control of the airplane when a control does not work normally.
Derivation
"Malfunction" comes from Latin malus (bad) + functio (performance), so literally "bad performance." "Failure" means a complete stop in working. Together they cover the full range -- from a control that works poorly to one that doesn't work at all.
Why Pilots Care
Recognizing and responding correctly prevents loss of control and is essential for safe recovery.
Grounding Statement
If a control will not move, moves too easily, feels unusual, or moves but does not produce the expected airplane response, treat it as a possible flight control malfunction or failure.
Intuition Check
Do not assume “failure” always means the airplane is uncontrollable or that a part has broken off. In this context, the term includes anything from a control that feels wrong or responds poorly to a complete loss of control function.
Example Sentence 1
After the elevator felt unusually heavy on rotation, the pilot declared a flight control malfunction and returned to the departure airport.
Example Sentence 2
Training covers flight control failure procedures that use trim and power changes to maintain directional control.