Some people have mentioned that you can download missions or scenarios for use with the offline practice arena. So how about some built-in training missions?
Have a series of missions that teach basic aerobatics and combat maneuvers. Set it so that once I am in flight, I can activate the training mission, and there would be a training plane with a recorded message telling me how to do a particular maneuver. Then I would follow the plane through the maneuver. It would repeat over and over until I exit the mission. There would be a separate mission for a loop, spit-s, roll, etc. Nothing real fancy, just the basics.
I firmly believe that someone brand new to Aces High, especially someone new to flying games, should spend some time in the practice arena learning how to fly, before he creates his online account. Creating some training missions like this could lower the frustration level for new players by helping them up the learning curve.