Well, I was using the game's ideal of "honorably" as a possible base, not the WWI aviators version (which would vary from aviator to aviator). If you think about it tho - what are the legitimate reasons for leaving a fight in the first 5 turns? According to the game's "honorable retirement" it's no engine, no fuel, no guns, or on fire (if I recall correctly). If ANY of those were true in the first 5 turns, I would have no problem with my opponent or myself fleeing from the battlefield. I would think even WWI aviators would agree there.
I suppose ultimately we need to ask for clarification in this argument.
1) What is the standards for "quitting"? I.E. What range of turns, what % of damage, etc.
once we know that...then the following should be asked:
2) When did the pilot retire?
3) Why did the pilot retire?
Using TXWard's example, the pilot retired on turn 18, with 39% damage, and the lead while being chased by two opponents. Yes, he left early, dishonorably. Possibly he left to preserve the lead (which honestly he would have kept even having been shot down, unless he had taken a LOT of shots beforehand).
Now analyze that and look at it from both sides, and make the call yourself.

The game's honorable retirement is; no guns, no engine, or no fuel (3 or less boxes), Fire is not included. Equating only these limited conditions to the concept of "honorable" retirement is silly. There are many reasons why a pilot or player would find it reasonable to exit a fight (or game). So, I am not discussing "honorable", but rather "reasonable" as the base for determining whether or not someone should exit a game. I also don't care about the example provided by TXWard. That is one case. I am looking at the overall situation.
other conditions under which someone might reasonably expect to be able to retire without penalty?