Definition
Small adjustable surfaces attached to the trailing edge of the ailerons that, once set by the pilot, hold the ailerons slightly deflected to counteract a steady rolling tendency without the pilot having to maintain pressure on the control wheel or stick.
Plain English
Tiny tabs on the back edge of the ailerons that the pilot can adjust to make the airplane stop wanting to roll one way on its own, so they don't have to keep holding the controls against it.
Context Anchor
Seen in aircraft control-system descriptions, preflight walkarounds, maintenance rigging, and discussions of correcting a steady left or right rolling tendency.
Derivation
Aileron' comes from the French for 'little wing.' 'Trim' here means to adjust something to its proper balance — the same sense as trimming a sailboat. So an aileron trim tab is a small wing-edge surface used to balance out roll forces.
Why Pilots Care
Allows hands-free maintenance of lateral trim, reducing pilot workload and preventing fatigue during prolonged flight.
Intuition Check
“Trim” does not mean decoration or cutting something shorter here. It means adjusting a control force so the airplane holds the desired position with less effort from the pilot.
Example Sentence 1
After leveling off in cruise, the pilot adjusted the aileron trim tabs to relieve the constant left-wing pressure caused by torque.
Example Sentence 2
With proper aileron trim tab settings, the aircraft maintains wings level during cruise without constant aileron input.