The Desert Combat mod for Battlefield 1942 is a lot of fun. The update they released yesterday has some neat stuff, including a working helicopter and a butt kicking T-72 tank.
Aces High is where I go for serious flying, but BF1942 has been good for dealing with my quake moods.
In response to the 'why not use ah?' question, Aces High doesn't have ground infantry and the same time of fast & furious action. BF1942 is an arcade game. Sometime you need a break from chess, and BF1942 is a good break.