While on an exercise, and attempting to return to base with a failing engine, he instead opted to ditch the plane in the estuary of the River Dysynini in Wales.  Losing control on the approach, he crashed into the water. The investigation suggested that having  an artificial left arm may have been the cause of the crash, as the flaps would have had to be held continually and the joystick held between his knees.  He lost his arm when shot down on his last mission over France in 1941. Held a POW for 2 years, he had resumed flying duties after being repatriated in 1943.

{For Your Tomorrow, Errol Martyn, Vol 2 p. 326]