BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

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AFMAN 11-217V1 3 JANUARY 2005
Figure 17.7. The Somatogravic Illusion.
17.3.1.4.2. G-excess illusion. The G-excess illusion depends on otolith-organ
mechanisms. The G-excess illusion is an exaggerated sensation of body tilt
caused by a greater that 1-G force on the otolith organs. The additional G force
(that amount greater than 1 G) increases the response of the otolith organs,
causing the false perception (illusion) of an excessive amount of pitch or bank.
When a pilot’s head is facing forward in a G-pulling turn, the G-excess effect
causes a false percept the aircraft has tilted backwards (pitched up). In the
absence of overriding visual cues, the pilot can make dangerous attitude control
errors to correct for the G-excess illusion. If the pilot is looking at the “9 o’clock
level” position while in a left turn, the G-excess effect would create the illusion
the pilot’s direction of gaze is above the actual direction; i.e., the aircraft is in less
of a bank than is actually the case. The pilot would compensate for the illusion by
overbanking. Because of the G-excess illusion, the pilot may be in a bank