In the gps based modes it still needs good compass info to know which direction to travel. Imagine if heading was 180 degrees out, the vehicle would head in the wrong direction completely and the harder it tries the further it gets from where it wants to be...basically a positive feedback loop situation.
Thanks, but how does this explain a fly-away in mid flight in ATTI mode? Not flying waypoints.
Atti or Attitude, depends on which multirotor I am flying. But, I never thought of the current position as a waypoint, but it does explain the toilet bowl effect when the compass calibration is off a bit.