Plain English Meaning

The nose of the aircraft bobs up and down a few times after something upsets it, then it settles down on its own.

Full Definition

Repeated nose-up and nose-down movements of an aircraft about its lateral (pitch) axis, occurring as the aircraft seeks to return to its trimmed flight attitude after a disturbance. In a longitudinally stable aircraft, these oscillations gradually reduce in size until the aircraft settles back to level flight.

Context Anchor

Seen in longitudinal stability discussions, especially when describing how an airplane responds after a gust, control input, or trim change.