Definition
The transition maneuver from a climb or descent to level flight at a target altitude, accomplished by smoothly adjusting pitch attitude and power so the aircraft arrives at the desired altitude with zero vertical speed and the selected airspeed.
Plain English
Stopping a climb or descent and settling the airplane into steady flight at the altitude you wanted to reach.
Context Anchor
Seen during instrument flying when using the attitude display, altimeter, vertical speed indication, and trend indicators to judge when the airplane is about to stop climbing or descending.
Derivation
Level comes from older words meaning even, flat, or balanced. In flying, that idea becomes flight that is neither climbing nor descending. Off adds the sense of bringing the climb or descent to an end.
Why Pilots Care
Prevents altitude and heading overshoots that can lead to deviations, traffic conflicts, or unstable approaches in instrument conditions.
Intuition Check
Leveling off does not mean the airplane instantly becomes level the moment you move the controls. It means you manage the transition so the climb or descent gradually reduces to zero at the desired altitude.
Example Sentence 1
Passing through 4,500 feet in the climb, the pilot began leveling off so the aircraft would settle at the assigned 5,000 feet without overshooting.
Example Sentence 2
During the descent the pilot started leveling off 150 feet above the assigned altitude so the aircraft would capture it smoothly.