FAA Commercial Pilot Airplane (CAX)Human Factors and ADMMedium
A pilot is making a night visual approach over a coastline where a line of well-lit boats parallels the shore below a sloping bank of clouds. The pilot notices the wingtip appears to align naturally with the line of clouds above the horizon, so they roll the aircraft to keep the wings level with this reference. This action places the airplane in an unusual attitude relative to the true horizon. Which illusion caused this error?
- ACoriolis illusion
- BAutokinesis
- CSomatogravic illusion
- DFalse horizon illusion
Show answer & explanationAnswer & explanation
Correct answer: D. False horizon illusion
A false horizon illusion occurs when a pilot mistakes a sloping cloud deck, ground lights, or a starlit sky for the actual horizon and orients the aircraft incorrectly relative to the true horizon, often resulting in an unrecognized bank.
Why the other options are wrong
- A. Coriolis illusion results from abrupt head movement during a prolonged turn, not visual horizon misidentification.
- B. Autokinesis is the apparent movement of a stationary light when stared at, unrelated to sloping references.
- C. Somatogravic illusion involves misperceiving pitch attitude from linear acceleration, not visual horizon confusion.
False Horizon Illusion
An illusion in which a pilot mistakes a sloping line of clouds, terrain, or lights for the true horizon, leading to an incorrect aircraft attitude.
- Common at night over coastlines, sloping cloud decks, or featureless terrain
- Can cause an unrecognized bank or climb/descent
- Combat by cross-checking flight instruments, especially the attitude indicator
Memory trick: Trust the gauges, not the glow.