I watched a program and they interviewed an RAF vet (I can't recall whether he was a bomber pilot or a bomber crewman) but he arrived, as a replacement, at his new base while the unit were on a mission. None of them came back.
I read somewhere where 60% of all RAF Bomber Command crewmen were killed, wounded, or wound up as a POWs over the course of the war. The highest casualty rate of any allied command of the war.