Page:CAB Accident Report, United Airlines Flight 21.pdf/74

 pilots testified that no difficulty was encountered in freeing the carburetors of ice almost instantaneously upon the application of heat. It is improbable that a momentary failure of one engine to take the throttle could have resulted from cooling of the motors, because, according to pilot testimony, one of the principal advantages of the drag approach under partial power is that the motors remain warm and available for an emergency.

The evidence indicates that at the time of impact both motors were under little, if any, power, and the similarity of their condition indicates that both engines were doing exactly the same thing at that time. However, this does not indicate that the engines were not used in an attempt to correct the stall or that both engines responded when that attempt was made because in all likelihood, after having attempted to avert the stall by a burst of power and realizing that his attempt was unsuccessful, Captain Scott did everything he could to minimize the crash by pulling back the throttles prior to impact.

Thus, while the evidence provided by the disassembly of the engines and by the eye-witnesses does not conclusively determine whether the left engine responded, it seems most probable that no engine failure occurred to cause the stall or to contribute to the accident.

From all of the evidence available to us, we conclude that the stall resulted from a failure of the pilot of NC 25678 to exercise that degree of caution and skill required to avert it and not from any condition or occurrence beyond his control.