The Civil Aeronautics Board ( CAB ) investigated Criminal_investigation the accident Catastrophe and , after interviewing Communication numerous eyewitnesses and examining Testing the debris field , were able to conclude Coming_to_believe that the initial failure of the aircraft had begun Process_start in the left Departing wing .

The investigation Criminal_investigation into the Northwest crash Catastrophe discovered Know a new phenomenon of harmonic coupling Cause_to_amalgamate within the wings of aircraft , which in the end Process_end was ultimately identified Check by the CAB as being the cause Causation of both break-ups .