aircraft. Most of these accidents resulted from a high-speed dive that was
initiated when the pilots were changing radio frequencies. All of these
accidents had a similar pattern of events.
(1) Pattern of events:
(a) Aircraft.
The aircraft were jet fighters or intercepters.
(b) Pilots.
The pilots were young and inexperienced.
(c) Procedures. The accidents usually occurred when landing,
in the approach pattern or in a procedural turn.
(d) Altitude.
The altitude was relatively low, usually less
than 2,000 feet.
(e) Environment. Instrument weather conditions with minimum
visibility or darkness prevailed.
(f) Diversions.
The pilot was requested to change radio
channels or modes.
(g) Position. Almost immediately thereafter, the aircraft
struck the ground at a terrific velocity and oftentimes in a near vertical
or inverted position.
(2) Accident investigation findings: During accident investigations
it was noted that the radio channel selector was set far to the rear of the
console. This required the pilot to turn his head down and to the right
while flying in a banked turn. By this maneuver, the pilot not only lost
monitorship of his instruments but placed himself in an optimum position to
experience the most deadly of all spatial disorientations (the coriolis
effect).
(3) Vestibular coriolis effect: The vestibular coriolis effect
results when one set of semicircular canals has equilibrated to a constant
angular velocity and a head motion is made in a plane other than the plane
of constant angular movement. When a second set of canals (out of the plane
of rotation and unstimulated by the rotation) is rotated into the plane of
constant movement, an angular acceleration is imposed on them.
Simultaneously, an angular deceleration is imposed upon the first set of
canals as it is rotated out of the plane of motion. This activation of
movement of endolymph in two canals also induces movement in the third
canal, resulting in a perception of motion in a plane in which no real
motion exists.
(a) Head movement forward and downward. A pilot yawing in a
clockwise direction at a constant velocity, pitches his head forward and
downward. This head movement places the vertical canal in a horizontal
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