Some might recall the incident when a Navigator ( who had already lost an eye in a previous Canberra incident) found himslelf skidding alone and inverted down the main runway at Bedford in a Hawk ,following a pilot ejection. IIRC his bone dome was ground down to the top of his skull in the process. Amazingly he carried on flying regardless and I last saw him at Wyton on Canberras in the late 80's .