FAA Instrument Rating Airplane (IRA)Aeromedical and ADMMedium
While holding in actual IMC, a pilot tilts his head down to retrieve a chart that has fallen to the cockpit floor during a turn in the holding pattern. Immediately he experiences a strong, disorienting sensation of rotation about a different axis than the airplane is actually turning on. Which illusion is the pilot experiencing?
- ACoriolis illusion
- BAutokinesis
- CElevator illusion
- DSomatogravic illusion
Show answer & explanationAnswer & explanation
Correct answer: A. Coriolis illusion
The Coriolis illusion occurs when a pilot moves his head out of the plane of an ongoing turn, stimulating multiple semicircular canals simultaneously and producing a strong, false sensation of rotation on an entirely different axis. This is one of the most disorienting illusions and pilots should avoid abrupt head movements during turns in IMC.
Why the other options are wrong
- B. Autokinesis involves a stationary light appearing to move, unrelated to head movement.
- C. The elevator illusion is caused by vertical accelerations such as updrafts, not head movement in a turn.
- D. The somatogravic illusion is caused by rapid linear acceleration/deceleration, not head tilting during a turn.
Coriolis Illusion
A vestibular illusion caused by moving the head out of the plane of a turn, stimulating multiple semicircular canals and creating a sensation of rotation or tumbling on a different axis.
- Occurs during sustained turns when head is tilted (e.g., reaching for a chart)
- Considered one of the most overwhelming and dangerous illusions
- Prevention: avoid sudden head movements during instrument flight, especially in turns
Memory trick: Turn your head, turn the world upside down