i just found this on the trainers website.
HEAD-ON SHOTS: A "head-on" is a shot when you are nose to nose with the enemy. It is considered bad form and the mark of a dweeb to take a head-on shot, especially on the merge but many people take them anyway. I guess the best line of reasoning I have heard on this is "It takes two to head-on"! For me personally, and for many others, it isn't much of a game if everybody goes straight at each other with guns blazing and whoever got the best roll of the dice from the computer (as far as hits, misses, and damage caused) wins. Do your best to avoid having to receive or give head-on shots.
Murdr says: While a front quarter shot is completely valid, when someone is intent on making a head on shot during the initial merge, it is a clear sign of an inexperienced player. The experienced player knows how to routienly avoid such shots while simultaniously gaining an angles advantage on their opponent. Hence while on player is trying to line up a head on shot, the other is already maneuvering to get on their six after the merge.
KILL STEALING: In Aces High, a damaged plane can spin helplessly to the ground after having its wing shot off in a good fight. The victor of this fight, assuming he is any good, is probably already looking for the next fight, and maybe even anticipating seeing who he killed. A kill stealer is someone who chases the tumbling, burning wreckage that was once a plane down to the ground, pumping it full of bullets, and gets a kill because he gets more hits into it before it hits the ground. This is the mark of a true dweeb who cares only for his score, not whether he is any good or not. While accidents do happen, don't shoot into planes that are already going down.