DON'T mount anything steel/iron i.e. ferrous/magnetic metal-wise on the leg near the compass. I'm not talking something magnetic/already magnetized....just something steel. Finally, after a replacement controller board, I have a working Tarot gimbal and was anxious to shoot some stabilized video. What to do quickly/temporarily to get the Hero3 off the ground...i.e. extra leg extension? The fastest quickest solution I could come up with, something I had seen in a picture (might have been aluminum wire), was cutting 2 lengths from a steel coat hanger, making two 90 degree bends, and taping them to the legs with about an extra 3 " extension. Looked great and solid. Went to fly...power up normal. NO error messages. I get into the air and after 10 seconds or so as I start some maneuvering, the bird gets unstable, unresponsive, out of control and I crash. Never had THAT happen before. I checked the Hero3 and wifi NOT on...my first thought. Maybe the new Tarot, powered through the aux cable was giving feedback to the FC. I tried powering up with the gimbal unplugged and it powered up OK, no error message, but this time I went through a compass calibration maneuver. Suddenly I am getting fast GRN_RED_GRN_RED. I try re-powering, re-calibrating compass multiple times but constant return to error signal. So I cut off the coat hanger legs. On power up I still got the error signal but after compass calibration maneuver it returned to slow green - red to grn---grn of satellite acquisition. It flew fine with the gimbal unplugged. Plugged in the gimbal and it flew fine. Lesson.....NO ferrous metal at all near the compass. Next question.....will the transmitter work from inside a car? Transmitting though the front windshield? Driving (as passenger)?