Douglas DC-2 accident at Pittsburgh-Allegheny County, United States of America, 25 Mar 1937 (NC13730)
On March 25, 1937, a Douglas DC-2 (registration NC13730) operated by Transcontinental & Western Air - TWA was involved in an aviation accident near Pittsburgh-Allegheny County, United States of America during landing or approach. 13 people were killed. Investigators recorded the probable cause as: It was determined by the US Bureau of Air Commerce that ice had built up on its wings and in the slot between the edge of its ailerons and the wing tips, and that the latter condition must have changed the airfoil contour and disrupted the flow of air around… This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 6 related events involving the same aircraft type or operator are linked below.
Probable cause
It was determined by the US Bureau of Air Commerce that ice had built up on its wings and in the slot between the edge of its ailerons and the wing tips, and that the latter condition must have changed the airfoil contour and disrupted the flow of air around the structure, leading to a loss of control. Soon after this accident, improved deicing equipment was announced to help deal with the threat to aircraft caused by the build up of ice.
— NTSB Determination
Accident narrative
On final approach to Pittsburgh-Allegheny County Airport, at a height of 500 feet, the aircraft rolled to the left, entered an uncontrolled descent and crashed short of runway. All 13 occupants were killed.
Probable cause (official findings): It was determined by the US Bureau of Air Commerce that ice had built up on its wings and in the slot between the edge of its ailerons and the wing tips, and that the latter condition must have changed the airfoil contour and disrupted the flow of air around the structure, leading to a loss of control. Soon after this accident, improved deicing equipment was announced to help deal with the threat to aircraft caused by the build up of ice.