Hmm you may have to go back and study reasons 101.
Because you seem to miss the piece where it targets the CLOSEST plane above 3k.
HiTech
HiTech, I don't know if there might be a flaw with your code or not, but like others said, the moment you pop 3K, you start getting hit by puffy ack. I've been in furballs off CV's, and those puffy ack guns go for whoever is above 3K.
It's not ALL guns focus one target then once that target is dead/under 3K, then it jumps to the next. ALL guns fire on ALL planes above 3K.
Not telling you how you run your game, or that you don't know your own game, it's just my observation and the observation of others.