Figure 19.
The oculogravic effect.
(4) Illusion of nose-down attitude: It is probable that the illusion
of a nose-down attitude occurs during decelerations caused by extending
speed brakes or otherwise reducing forward velocity. If this is true, the
illusion has not yet been reported as causing an operational hazard.
f. Inverted and Elevator Illusions. Several variations of the
oculogravic effect occur to include the inverted and the elevator illusions.
Both of these are based on the same mechanism as described for the
oculogravic effect.
(1) Inverted illusion: The inverted illusion variation occurs during
the pushover from a climb into level flight. Under these circumstances, the
centripetal and tangential acceleration acting upon the aircraft yield an
inertial vector which, when combined with the gravitational vector, create a
resultant vector that is rearward and
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