Flip training HORIZON mode is a combination of the ACC/ANGLE mode and regular acrobat mode (no auto-level). When you are not touching the roll/pitch stick then the copter auto-levels, but when you start putting in bank or pitch angles then the copter morphs to acrobat mode. This mode is basically a flip-trainer. It allows you to full bank or pitch to begin a flip and then let go of the stick to have the copter right itself. It really works, and is an awesome feature, but you can still crash the copter if you attempt it at low altitude. Altitude is your friend here!