My mother’s brother, who passed away unexpectedly in 2008, flew 28 operational sorties (two short of a full tour) as Flight Engineer on Lancasters Mk.I & III with 61 Squadron (Skellingthorpe) and 83 Squadron (Coningsby) during WWII.
Note: Bomber Command crews suffered an extremely high casualty rate: 55,573 killed out of a total of 125,000 aircrew (a 44.4% death rate), the highest loss rate of any major branch of the British armed forces. A further 8,403 were wounded in action and 9,838 became prisoners of war. Bomber Command aircrew had a worse chance of survival than an infantry officer in World War I.