Also, don't forget to look at the people. Sometimes it's very worth turning around just when the show's getting most interesting.
A small second body of some kind with a wider lens can be very handy.
Also, pay attention to things like shoes, hats, and not to carry *too much* gear to walk a long way in, even if almost anything might be useful at an air show. (Nice to have friends.) I definitely think of these, because for someone as sun-sensitive and arthritic as myself, it's basically insane to attend an air show of any kind, even on a good day, but one day when I found myself shooting that huge one in Wisconsin (How huge could it be? I asked, unknowingly, applying like SPF 80 with a hose...
) Toward afternoon, I saw some folks doing almost as badly with all they'd been carrying all day. Not that I could blame them for wanting to bring nice stuff.