David CL Francis wrote:

I have read that 1% aircraft were expected to be lost in collisions
over the target.

Not with the USAAF, though that figure may have been true at one time for RAF
Bomber Command. For the Cologne raid in early '42, the forecast was for two
collisions for roughly 1,000 aircraft. As it turned out, one occurred over
Europe and a second one over the UK on return. That's less than half of one
percent for that raid.

George Patterson
To a pilot, altitude is like money - it is possible that having too much
could prove embarassing, but having too little is always fatal.