I'am not angry (do not get fooled by

)
but:
The original boardgame has rules that you can find here:
http://www.youplay.it/play/bm_GameRulesFull.aspIf you bother to read and get to the escape section, they say
Escape
Eventually, because his plane has suffered severe damage, is about to run out of fuel, or has run out already, a player may wish to escape from combat and head back to the aerodrome.
A player is considered to have escaped if his plane flies off the edge of the playing surface behind his side’s start line. (An aircraft may not fly off the edge anywhere else.)
Honor demands that a player not attempt to escape until he has a good reason for doing so.
The game is over once all aircraft of one side have been shot down or have escaped.
Ah I miss the days of being a game rules lawyer, that was the great thing about old wargames - rules and exceptions. Now as I recall (I can't check at the moment because I'm out of town and I can't get out my old copy of BM) the 'start' lines are drawn several hexes into the map - so, technically I belive that even in the original there were hexes on the top and bottom that could be exited from legally.
But for some real rules fun let's talk 3R 4th ed.!