I've noticed on other GPS's that if you leave them set for quite some time, leaving the track recording on, you'll end up with a track that looks like a scribble, with points up to several yards, or tens of yards away from the actual location. Each time one of these points are plotted, the GPS thinks it is moving in that direction. The iFly doesn't zoom in enough to show movements this small, but the arrow/aircraft will rotate to the direction calculated.