Definition
A condition in which the aircraft's trim controls have been adjusted so that it maintains straight-and-level flight at a chosen airspeed without the pilot needing to hold pressure on the controls. In this state, the control surfaces are positioned to balance the aerodynamic forces acting on the aircraft, allowing it to fly hands-off in level flight.
Plain English
The aircraft has been set up so it flies straight and level on its own, without the pilot having to push or pull on the controls to keep it there.
Context Anchor
Seen when setting or checking the attitude indicator during instrument flying, especially after the airplane is stabilized in straight-and-level flight.
Derivation
Trim comes from the old nautical sense of adjusting a ship so it sits balanced in the water. In aviation, trimming means making small adjustments to balance the aircraft so it flies steady on its own.
Why Pilots Care
Reduces pilot workload and prevents fatigue during prolonged level flight segments.
Intuition Check
Trimmed does not mean the airplane is locked in place or can be ignored. It means the control forces are balanced for the current speed, power, and setup.
Example Sentence 1
Once established at cruise altitude, the pilot trimmed the aircraft for level flight and began the cross-country leg.
Example Sentence 2
Once trimmed for level flight, the airplane maintained altitude with minimal control inputs.