Which statement about Coriolis Illusion is true?

• A. The illusion can be triggered when the head is moved in a plane different from the flight path.
• B. The illusion only occurs in bright daylight.
• C. It is not related to vestibular input.
• D. It can be cured by simply yawing the aircraft.

Answer: (A)

Coriolis Illusion happens when you’re in a turn and you move your head in a plane that isn’t aligned with the turn’s plane. Your inner ear’s semicircular canals sense rotation in specific planes. While you’re turning, those canals in the turn plane are stimulated. If you tilt or move your head in a different plane, the inertia of the fluid (endolymph) can deflect a canal that isn’t signaling a turn, producing a false sensation of rotation or bank in a direction that doesn’t match the actual aircraft attitude. That’s why moving the head in a plane different from the flight path can trigger the illusion.

This isn’t limited to daylight, and it is a vestibular (inner-ear) phenomenon, not something you can fix by yawing the airplane. The safe response is to rely on the instruments and minimize head movement to maintain orientation.