FAA Private Pilot Helicopter (PRH)Human FactorsHard
While flying in IMC and holding a steady banked turn, a helicopter pilot reaches down to pick up a dropped chart, tilting his head forward and to the side. He suddenly experiences an overwhelming sensation of tumbling or rotating about a completely different axis. Which illusion is this?
- ACoriolis illusion
- BThe leans
- CSomatogravic illusion
- DGraveyard spiral
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, disturbing fluid in a semicircular canal not previously stimulated. This creates conflicting signals that are perceived as violent tumbling or rotation in an unrelated axis.
Why the other options are wrong
- B. The leans results from a fast correction to a slow-onset turn, not head-tilt-induced tumbling.
- C. Somatogravic illusion relates to linear acceleration cues, not head-movement-triggered tumbling.
- D. Graveyard spiral results from loss of turn sensation, not sudden tumbling from head movement.
Coriolis Illusion
An illusion causing a sensation of tumbling or turning on a different axis when a pilot moves his head during a sustained turn, disturbing fluid in multiple semicircular canals.
- Triggered by head movement during a prolonged turn
- Considered one of the most disorienting illusions
- Avoid quick head movements during instrument flight, especially in turns
Memory trick: Tilt your head mid-spin and the world tumbles sideways.