Out-of-Control Flight
Glossary
N
Negative-g Spike: Transient increase in negative-g force.
P
Post-Stall Gyrations (PSG): The transitional period of positive or negative acceleration between depar-
ture and either recovery or spin. It is characterized by random, uncontrollable motions of the airplane
about any or all axes. Much of the motion can be attributed to inertia forces and moments.
S
Sideslip Angle: Relation between the displacement of the aircraft centerline from the relative wind rather
than from a reference axis.
Spin: A maneuver combining yaw rate and stalled AOA in which both wings are stalled and produce
differential aerodynamic forces resulting in autorotation.
Spiral: A maneuver during which the aircraft descends rapidly toward the earth in a helical movement
about a vertical axis similar to a spin axis. However, the AOA during a spiral is less than the stall AOA
resulting in a spiral rather than a spin.
Stall: That AOA beyond which a further increase in AOA will produce a decrease in lift.
Static Directional Stability: The “weathercock” tendency of the aircraft or the tendency of an aircraft to
return to steady-state flight after a disturbance in the horizontal plane.
Steady-State Spin: A spin in which all aerodynamic forces are balanced.
T
Transverse G: The force of acceleration measured in ft/sec2 acting along the longitudinal axis of the
aircraft during acceleration or deceleration.
W
Wing Walk: An unintentional maneuver during approach, waveoff or takeoff where very high AOA and
pitch attitude will result in a loss of horizontal stabilator authority. The wing is positioned in a stall condition
and the aircraft is kept aloft by the thrust vector. Ailerons or elevators remain marginally effective resulting
in wing walk.
(9-98) Original
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