somatogravic illusion

An optical illusion that can result in spatial disorientation. A rapid acceleration during takeoff can create an illusion of being in a nose-up attitude. The disoriented pilot will push the aircraft into a nose-low, or dive, attitude. A rapid deceleration by quick reduction of the throttles can have the opposite effect, with the pilot pulling the aircraft into a nose-up, or stall, attitude. See also oculogravic illusion.

When head is level or when aircraft is flying at constant speed, sensing hairs are erect. However, if the head is raised or if the aircraft accelerates the sensing hairs bend backward. If visual clues are absent or the pilot is not concentrating on instruments, any acceleration will induce a sensation of nose-up attitude forcing a nose-down attitude.