FAA Sport Pilot Airplane (SPA)Human Factors and ADMMedium
During a night takeoff over dark terrain, a pilot experiences rapid acceleration on the runway. Without visual references, the pilot suddenly feels as though the aircraft has pitched up excessively and instinctively pushes forward on the control stick. What illusion is the pilot experiencing?
- AFalse horizon
- BSomatogravic illusion
- CCoriolis illusion
- DAutokinesis
Show answer & explanationAnswer & explanation
Correct answer: B. Somatogravic illusion
The somatogravic illusion occurs when rapid linear acceleration, such as during takeoff, is misinterpreted by the vestibular system as a nose-up pitch attitude, prompting the pilot to push the nose down dangerously close to the ground. Trusting flight instruments rather than bodily sensations prevents this hazard.
Why the other options are wrong
- A. A false horizon involves misreading sloped cloud decks or terrain as the horizon.
- C. Coriolis illusion involves rapid head movement during a turn, not linear acceleration.
- D. Autokinesis is a stationary light appearing to move, unrelated to acceleration.
Somatogravic Illusion
A vestibular illusion in which rapid linear acceleration or deceleration is falsely perceived as a change in pitch attitude.
- Common during rapid takeoff acceleration or go-arounds
- Causes pilots to push the nose down, risking controlled flight into terrain
- Combat by trusting the attitude indicator over bodily sensation
Memory trick: Speed feels like the sky is tipping — trust the gauges, not the gut.