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The Porpoise

Definition:  The Porpoise is a series of bounces from the main gear to the nose gear to the main gear.  Which if allowed to continue, will render the aircraft uncontrollable resulting in aircraft damage and possible image or loss of life.

Cause:  It is usually caused by overcontrolling the elevators in an effort to correct a bad landing, or by attempting to force the aircraft onto the ground at an excessive airspeed.  A nosewheel first landing at high airspeed practically assures a porpoise entry.

Cure:  In accordance with the tech order the pilot should recover in the following manner;  "If porpoising should develop, position the control stick in neutral or slightly aft of neutral and hold it there, while simultaneously advancing the throttle to 100% rpm.  (Do not attempt to counteract the bounce with opposite stick movement, since the combined reaction time of pilot and aircraft is such that control movement aggravates the porpoising.)  The object of this first step is to damp out the oscillation as soon as it begins by restricting control movement and by getting the aircraft completely airborne again, where further bouncing on the landing gear is impossible."