Just how good was German Flak

[Jon]

Thanks for the info regards the US AA.

Interesting as i am reading about the massive battles over Malta, the British and Maltese AA here was also excellent and brought down many Luftwaffe bombers and fighters. Looks to be the more practice (targets) you get obviously the better you will get.
And the Luftwaffe flak arm certainly had many targets.

One further question on Proximity fuses, how close to the target did they have to be for the fuse to detect and detonate?