Has anyone noticed that if you fly for example from L.A. to Rome and your flightplan takes you up over Canada and Greenland, that if you don't monitor your "greenline" GPS plan (I sometimes just make a flightplan just to see the route then fly on my own with Autopilot)your plane goes way off the heading? I've left it on a few times and gone out and the plane just flys around in circles off the heading. Today I left for an hour and had it in 4X speed and when I came back it had done about 20-30 loops up over Canada! The autopilot was set to about a 65 degree heading and pretty much aimed at England yet it always does/did this. Any Ideas? Thanks