Fight to the Death

S5, E1: What caused BEA Flight 548 to suddenly drop from the sky and crash to Earth, killing all 118 people aboard? When weather and engine failure are ruled out, examiners from Britain's Accidents Investigation Branch turn their attention to the flight's crew. Unfortunately, it's 1972, a time when cockpit voice recorders were not required, leaving the AIB team little to work with. See how they finally solved this puzzle, and how a rift between the flight's captain and his young crew may have played a lethal role in this tragic accident.