Out-of-Control Flight
Aerodynamic Principles
POST-STALL GYRATIONS (PSG)
The random and uncontrollable motions of the aircraft about any or all axes following a departure from
controlled flight, but before the incipient spin phase. In a PSG, much of the motion can be attributed to
inertial forces and moments.
INCIPIENT SPIN
The initial, transitory phase of spin, characterized by yawing, rolling, and pitching motions during which it is
possible to begin to identify the spin mode. Rotational motion of an aircraft following a stall, but prior to the
equalization of aerodynamic and inertial forces resulting in steady-state spin or recovery. Motion is charac-
terized by:
1. Stalled AOA throughout
2. Rotation in the direction of the spin
3. Varying roll, yaw, and pitch rates
4. Average rotation rate usually slower than steady state
FULLY DEVELOPED SPIN
The final phase of a spin, characterized by a sustained yaw rotation and a stalled AOA. Aircraft motions
from turn to turn are repeatable and consist of a yawing, rolling, and pitching helical motion in which the
aerodynamic and inertial moments or forces are in balance. It is characterized by autorotation. That is,
the aircraft will continue to spin without prospin controls. The spin is self-sustaining.
OUT-OF-CONTROL RECOGNITION
Out-of-control flight (departure from controlled flight) is comprised of two elements aerodynamic stall and
yaw. Generally, impending departure from controlled flight is indicated by one or more of the following
symptoms:
1. Mushy flight controls
2. Unresponsiveness to control inputs
3. Buffeting and buffet noise
4. Wing walk
The following are fairly unmistakable indications that you have entered uncontrolled flight:
1. Excessive yaw rate
2. Spinning or tumbling
3. Decaying airspeed and uncontrollable altitude loss
(9-98) Original
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