Perhaps we are approaching the problem wrong. We are looking at the symptoms rather than the problem itself. The ENY currently calculates all players on a side, then compares those numbers to the other sides, then via an algorithum changes the ENY accordingly. Perhaps there is a way that inactive players (not in planes, but in the tower for example) could still be afk, but not contribute to the ENY. Yet not be able to instantly spawn, in other words, not be able to abuse the 'immunity' given in the tower to spawn low ENY planes when ENY is high...
Other than my previous ideas on the matter, I am unsure of how to solve this issue. I don't want to 'punish' players going afk either for Real life tasks or for long climbouts, but I don't want those who are 'fighting the fight' and playing the game, to suffer because of the others either. Delicate balance, there is an answer here, but we need to find a method that benefits BOTH sides of this coin and doesn't punish those who are AFK via kicking them offline.