Plain English Meaning

A false sense of tumbling caused by moving your head suddenly while in a steady turn. The inner ear gets confused and tells your brain the airplane is rolling or pitching when it isn't.

Full Definition

A spatial disorientation illusion that occurs when a pilot, after holding a constant turn long enough for the fluid in the inner ear's semicircular canals to stabilize, makes an abrupt head movement (such as looking down at a chart or up at an overhead switch). The head movement stimulates a different set of canals at the same time the original sensation fades, creating a strong but false sensation of tumbling or rolling in a plane that has nothing to do with the airplane's actual movement.

Context Anchor

Encountered in instrument flying and night flying discussions, especially when pilots are warned not to make sudden head movements during without a outside .