Some organizational changes might do the trick!
I think the dueling arena should have a name change to "Basic Game" then have several permanent and several roving mid air spawns. (you can still take off from an airport if you wish) Also have as a default setting an elimination of the stall, don't let the planes climb to infinity mind you, just make them hang on their props, stationary, like so much fruit until the pilot changes the direction. The basic game will give newbies a chance to learn flying skills which later he can learn how to land and what the stalls are about in the main arena. Many people just want a shoot em up game anyway, so AH could simplify a few more things. When an older player is in the now old dueling arena he can change things to get a real duel in a grudge match. Like changing the stall setting etc.
Next get rid of the early and mid war arenas, When one side or the other out numbers the others make them play first the mid war craft, then the early war craft before the map is won. Once one side has to play with early (or mid war) craft put perk points on all mid war and late war craft so that perk points mean something for a change. In other words once you have to play with a mid war fighter because you're wining, enable a late war craft for a minimal perk cost, otherwise, play as usual late war arena rules.
Also get rid of the training arena, no newbie wants to train, he wants to play! Keep the offline arena of course for flexibility but make it that everyone trains in the dueling arena. That way, a newbie can just switch fields (or spawn points) and he's off to try his new knowledge on another newbie.