Why so gung-ho about shooting down friendlies to "train"? As pointed out, the DA is perfect for training if you want to be able to damage/down a plane. Yeah, you can't be on the same side, but you can tune to a vox channel from 200-299 (or squad if you're in the same squad) and talk across sides. No reason to turn off killshooter for the whole arena just so you can down a friendly.