The Man Who Fell from the Sky

Alfred Lowenstein was a very wealthy financier.  On July 4, 1928, he departed in his Fokker FVII(a) Trimotor from London, bound for Brussels, accompanied by his pilot, co-pilot, valet, male secretary and two female stenographers.  Somewhere over the English Channel he disappeared from the plane.  The crew all swore he had accidentally fallen from the aircraft, but an RAF pilot later insisted:

"Any person wishing to get out of the door, which opens towards the motors, would have to push a piece of woodwork roughly ten feet square in area, against a slipstream of 120 miles per hour, assisted by the backwash of two 150 horse power motors.  The backwash of these alone is enough to knock a man down when standing on the ground.

Even if a man could get it open, a super-strong man, as soon as the pressure was released the door would slam shut.  His body would be caught and held fast in the closing door.

Furthermore, as soon as the outside door was opened the slightest bit, everyone inside would be aware of it.  A blast of wind would blow through the cabin.  It is impossible, supposing a man did leap from the machine, that the passengers should not know something had happened."

The unsolved mystery is explored thoroughly in William Norris's book, The Man Who Fell From The Sky (Viking, 1987).