Sunday, June 16, 2013

Sudden Wing Drops

Early in our flying training we were warned about wing drops i.e. one wing suddenly dropping (and the other rising consequently). This can happen when there is insufficient lift generated on that particular wing and it stalls. The loss of lift in turn can be caused by a drastic drop in airspeed caused by the aircraft getting into too high an angle of attack but with insufficient thrust to maintain it. Both wings can stall at the same time, in which case the pilot just has to perform the normal recovery. In many instances though, and particularly with some aircraft, one wing will stall first and if the correct action is not taken, the aircraft will enter a spin - a more serious situation than a stall.

Sometimes though, that wing drop occurs due to a sudden drop in airspeed arising from a change in wind direction or speed especially when it is gusting. I was once caught in this situation as I was flying straight and level on a windy day and suddenly the right wing rolled down sixty degrees and my passengers were alarmed. On another occasion,  I was landing at Tioman Island and the sea breeze was gusting onto the runway. The aircraft was just about 10 feet above the threshold when the left wing rolled down about 30 degrees.

On both occasions I instinctively kicked hard on the opposite rudder and used as little aileron as possible and managed to right the aircraft in time. I had learned from my instructors during early training that when the airspeed is low, one cannot use too much aileron to right an aircraft. The wings do not have enough airspeed to react to the ailerons' deflection and will fail to right the aircraft. Only the wash from the propeller in front onto the empennage at the back will be able to act on the deflected rudder and roll the wings back to level via an indirect effect.

Tried and true. 

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