In MMORPGs like World of Warcraft and EverQuest there is a delay, 20 seconds and 30 seconds respectively, between telling the game to logout and actually logging out. They do this to prevent the player from escaping dangerous situation they got into by logging out.
If Aces High were to add a shorter, say 5-10 seconds, delay to despawning after a mission it would do a lot to eliminate issues such as AA vehicles ending their sorties just as the bombs are dropped and then immediately respawning after they land. And 5-10 seconds isn't so long that people won't bother landing anymore.