Ok I’m not the one to ask because I don’t know. We currently use the 7th addition rulebook which was published in 1982. Can’t answer for earlier versions.
I’d recommend the 7th Edition rule book (The one where TSR changed the name of the game to Dawn Patrol). If you have one of the earlier Fight in the Skies books you can play with it, the changes were all in details, not in the substance of how the game works. Really the only extensive changes from 4th to 7th edition were added aircraft and the roll-up charts to support them.