Colin,
The heavy casualties suffered by the heavy bombers of the RAF Bomber Command during WW-II were horrific...
Here is an estimate of Bomber Command casualties found on Wikipedia
http://en.wikipedia.org/wiki/RAF_Bomber_Command
"Bomber Command crews also suffered an extremely high casualty rate: 55,573 killed out of a total of 125,000 aircrew (a 44.4% death rate), a further 8,403 were wounded in action and 9,838 became prisoners of war. This covered all Bomber Command operations including tactical support for ground operations and mining of sea lanes.[clarification needed][29] A Bomber Command crew member had a worse chance of survival than an infantry officer in World War I.[29] By comparison, the US Eighth Air Force, which flew daylight raids over Europe, had 350,000 aircrew during the war, and suffered 26,000 killed and 23,000 POWs.[29] Of the RAF Bomber Command personnel killed during the war, 72% were British, 18% were Canadian, 7% were Australian and 3% were New Zealanders. [30]"
The numbers that caught my attention were the comparison of deaths and POW status. Bomber command had 55,573 crewmembers killed while 9,828 became prisoners of war. The US Eighth Air Force flying daylight missions had almost an equal number of crewmen captured as killed (23,000 POW against 26,000 kiled) that is a 7.4% death rate out of the 350,000 aircrew vs. the 44.4% death rate of Bomber Command.
I wonder what the reason was for this remarkable difference? Could it have been easier for U.S. B-17 and B-24 (which made up the bulk of 8th Air Force aircraft) crews to bail out of those aircraft than it was for RAF aircrews to exit crippled aircraft. It would be interesting to learn the percentage of death vs. POW status for aircrews by aircraft type.
You probably have seen this site but, it has some excellent information regarding the RAF Bomber Command.
http://www.rafbombercommand.com/master_welcome.html