← All explained questions · Supplemental · VIII — Basic Instrument Maneuvers
What is the correct response to spatial disorientation in IMC?
Choices
Look outside, use peripheral vision to find the horizon.
In IMC there's no horizon to find.
✓ Believe the instruments.correct
specifically the attitude indicator. Trust the instruments over inner-ear sensations, which are notoriously unreliable in IMC. Use straight-and-level autopilot if available. The vestibular system can't reliably detect attitude in IMC — the inner ear adapts to constant turn rates after about 20 seconds, leading to powerful 'leans' and 'graveyard spiral' illusions. The only reliable input is the instruments. Trust the AI, ignore the seat-of-the-pants. If autopilot is available, engage it to remove fly-by-feel temptation.
Close your eyes for 30 seconds to recalibrate.
Closing eyes worsens the situation.
Increase airspeed to break the disorientation.
Speed increase doesn't fix orientation problems.
Why
specifically the attitude indicator. Trust the instruments over inner-ear sensations, which are notoriously unreliable in IMC. Use straight-and-level autopilot if available. The vestibular system can't reliably detect attitude in IMC — the inner ear adapts to constant turn rates after about 20 seconds, leading to powerful 'leans' and 'graveyard spiral' illusions. The only reliable input is the instruments. Trust the AI, ignore the seat-of-the-pants. If autopilot is available, engage it to remove fly-by-feel temptation.
FAA source: PHAK Ch 17, AIM 8-1-5; PHAK Chapter 17 — Aeromedical Factors; AIM 8-1-5 Illusions in Flightbrowse the reference library →
Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question.