If a fighter and a bomber fly over an AA gun to the same battle, you use two dice and the attacker chooses what he loses. If they are doing separate attacks, roll them that way.
This is how you should figure it:
- Declare all attacks including flight plans.
- Choose one attack, a regular battle or a SBR.
- Roll one die for each plane that flies over an AA gun in each territory.
Say you are making a SBR on Karelia and also attacking Russia with two fighters that fly over Karelia. Choose the SBR first (I seem to remember the rules saying do these first anyway), so roll 1 die for the bomber. Then do the Russia attack. Roll two dice for flying over Karelia, then a die for each that survives to attack Russia. On the way home during non-combat, AA guns don’t fire.
I think that’s how it’s done based on what I know from SBRs. I’ve been proven wrong by official clarifications recently, so take it with a grain of salt. It’s just how I’ve always done it.