I tried to fly today-out of town in a paddock - no power lines no trees - just open land and blue skies and sunshine. But when i tried to calibrate the compass, I just coninued to get a warning stating that there was a compass error, and I should switch P-GPS off. When I checked the sensors, they were quite low (1300-1390). I did it about 30 times, and only twice did the sensors readings look OK (about 1500). I did take off but only hovered about 2 metres above the ground and moved around a bit but onlt a metre or two. The aircraft appeared to have a bit of difficulty flying in a straight line. I ran the battery down to about 30% and landed. i then tried another battery, but the same thing happened. I checked the IMU and it said the IMU calibration was OK. Does anyone have any clues as to how I can get a good quick calibration?