FAA Instrument Rating Airplane (IRA)Aeromedical and ADMMedium
A pilot in IMC enters a gentle, coordinated turn that goes undetected by the vestibular system. Losing altitude, the pilot senses only a descent and pulls back on the yoke without correcting the bank, tightening the turn and accelerating the descent. This dangerous chain of events is best described as a:
- AAutokinesis
- BCoriolis illusion
- CElevator illusion
- DGraveyard spiral
Show answer & explanationAnswer & explanation
Correct answer: D. Graveyard spiral
A graveyard spiral occurs when a prolonged, coordinated turn stops being perceived by the vestibular system, and the associated loss of altitude is misinterpreted purely as a descent. The pilot's instinctive back-pressure on the controls, without correcting bank angle, tightens the spiral and worsens the descent rate rather than recovering altitude.
Why the other options are wrong
- A. Autokinesis concerns a stationary light appearing to move, unrelated to turning flight.
- B. Coriolis illusion requires an abrupt head movement, not a sustained level turn.
- C. Elevator illusion is not a recognized FAA spatial disorientation term.
Graveyard Spiral
A dangerous illusion in which a prolonged coordinated turn goes undetected, and the resulting altitude loss is misperceived as a straight descent, leading the pilot to increase back-pressure and tighten the spiral.
- Occurs during sustained, coordinated turns in IMC
- Pilot senses descent but not the bank
- Correcting only pitch (not bank) worsens the spiral
Memory trick: Feel like falling straight? Check your bank before you pull.