Although the average loss per individual mission was often under 5% for the pilots who flew in the British Bomber Command, the fact that they flew 30 missions per tour meant a crew had less than a 1 in 4 chance of completing it. Once you signed on, there was a 75% statistical chance you wouldn't survive. Nor were these estimates far from the truth. Almost sixty percent of Bomber Command, a total of 55,000 men, were killed. They had an easy time compared to German U-boat crewmen, who lost 630 men out of every thousand.

Regarding the odds of coming back alive, the above seems correct and would no doubt prove out using the overall numbers but each mission was an independent event Statisticians will argue you into the ground that the odds of being killed are always under 5%.

Has nothing to do with your point but as a former white knuckle frequent flyer it is something that has always interested me.