Air unit AARs for air to air combat are useless unless corroborated against the other sides AAR. And using a single unit as representative of overall trends is the sort of thing that actually does make me angry so please dont do that.
PLEASE look at the goddamn numbers for allied reports on lost hurricanes, De502 and He75 in Air to Air combat. I think you will be quite surprised.
To explain (not to maniac specifically) why this is true:
Imagine that a flight of five fighters from each side meet each other in a head on fight, it turns into a free-for-all dogfight, and a given Allied pilot has fairly bad luck. In the first pass, he takes a hit to the engine that stalls it out, sending him into a flat spin. He's high enough up that he can get the engine restarted and regains control. Shortly after this, another burst sets his left wing on fire, but the wing fuel tanks are leaking so bad that the fire quickly starves. Just as he gets under control to perform an emergency landing, an Axis pilot settles behind his damaged plane and turns it into a fireball. The remaining planes -all damaged- break off due to lack of fuel, and the Axis squadron commander confidently claims his men three kills, all of which are confirmed by other pilots. Meanwhile, the Allies only lost a single plane. Is the Axis lying?
No. In this hypothetical battle, the planes from both sides are snapping off short bursts at any opportunity, and three seperate pilots watched their bullets inflict what should have been (and probably would have eventually, but the pilot might have salvaged something from the first two) fatal - a stalled plane spinning out of the sky, a plane covered in flame, and one simply exploded. Even in such a small fight, there's no way for them to tell that that was the same plane each time, and each sighting should have been a kill. Thus, they believed that three planes were destroyed. That's before you get into pilots seeing things from different angles and thinking they're different events in the debriefing.
Scale this up to a full-sized battle, with dozens or hundreds of aircraft per side. It's extremely easy to think that you killed many more aircraft than you actually did. The solution here is to look at the records from both sides - if the Axis claim 3 kills, and the Allies have "1 destroyed, 4 damaged", something is wrong.