Definition
The act of adjusting the elevator trim control to relieve continuous control-yoke pressure required to hold a desired pitch attitude during a phase of flight such as takeoff, climb, cruise, or descent. Proper elevator trimming sets the trim tab (or equivalent trimming device) so the airplane maintains the selected pitch attitude with little or no sustained back- or forward-pressure on the yoke.
Plain English
Using the trim wheel or switch to take the constant push or pull off the control yoke, so the airplane will hold its nose at the angle you want without you having to fight it.
Context Anchor
You see this during the before-takeoff check and in normal takeoff errors, where the trim should be set correctly before the takeoff roll begins.
Derivation
‘Trim’ comes from the Old English ‘trymman,’ meaning to set in order or balance. In flying, trimming sets the controls in balance so the airplane flies hands-off at the chosen attitude.
Why Pilots Care
Proper elevator trimming reduces pilot workload, prevents over-controlling, and allows smooth rotation and climb without constant stick pressure.
Intuition Check
Trimming does not mean cutting something or making it neat. In this context, it means adjusting a balance setting so the airplane is not fighting your hand pressure.
Example Sentence 1
After establishing the climb attitude, the pilot performed elevator trimming to relieve the back-pressure on the yoke.
Example Sentence 2
Failing to use elevator trimming during the initial climb forces the pilot to hold continuous back pressure.