EDIT: The information below is outdated.

In the tips and tactics forum (http://fm.en.kupaisky.com/Community/Forum/List.aspx?category=D01) click "View Old Data" and check out "Adalbert's guides on ability". Be careful, because the threads there are actually backwards (the first post is still on the top of every page) but the second post actually appears at the very end, and so on.

In that thread:

9) aircraft
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This is a not activated ability - it has NO EFFECT WHATSOEVER on anything related to pilots.

10) fighter
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The true Fighter ability is responsible for how well your pilots in their planes can
attack other planes...

11) bomber
========
Bomber ability is the only ability that is responsible for resistance against enemy fire -
both AAW and gunfire from Fighter (or other) planes. Again - for scouts, fighters as well
as bombers...

There's more details in the thread if you care to know more.

I was under the impression that these stats were changed. Fighter corresponds to fighter attack AND defense, bomber corresponds to bomber attack AND defense. I could be wrong though. Anyone care to clarify?

Confirmed:
Aircraft: Still disabled

Fighter: Used for attack and defense (AAW and plane gunfire) of Fighters

Bomber: Used for attack (Not bombs or torps, gunfire only) and defense (AAW and plane gunfire) of Dive Bombers or Torpedo Bombers

All other features are set values that do not change and how planes act is all run on the same AI.

Theories:
Scouts appears to use the fighter stat since my +12 fighter stat scout could kill my +10 before I b/v/ed the +12.

Last I looked its lost vets down to 202 vets and max experts no rookies...I'll have to roll more later. Oh it occasionally kills T3/4s when using T5 scout. :)

Read what I posted above that maybe?

Aircraft = scout now.