Okay I've just started playing this game and seem to have discovered a problem, some off the aircraft in Famous aces require a B damage deck. My box contained no B damage deck cards also I was bought the Immelman pack in which many aircraft require a B damage deck and one requires a AB damage deck.

Have I got a box that is missing cards?

What is the essential difference between damage deck A and damage deck B.

If they dont supply you with them then this game, as good as it is, has been sold incomplete and is unfit for purpose.

The B-damage deck is only included with Watch Your Back.  Use the rules in Burning Drachens to convert your A-damage deck to B-damage (essentially divide the result by 2).   http://new.fantasyflightgames.com/ffg_content/wings-of-war/media/wingsofwarbdrules.pdf

Famous Aces is sold as an A-damage game.  You are not missing any damage cards, nor is the Famous Aces set incomplete.  IMO, the B-damage planes have been included as an "enticer" so you can see the other additions this game can offer should you wish to expand your horizons.

Thanks Shvak that is very helpful to know, my enjoyment of the game will be greatly enhanced knowing I can use all the aircraft.

 Also given these are bonus planes as a taster meaning you balance encounters/missions using them yourself, and the way many pilots and observers tinkered with their armaments you could just play with an A deck till you get a B deck and assume that the pilot of that card mounted an extra Vickers or a twin mount gun