Have you actually flown with it, yet? You won't see the behavior you expect if you're just using it in your living room.
When in "Follow Plane" mode, the plane starts out in the middle of the screen when you're not in motion. Once you start moving and the iFly has confidence it knows what direction you're headed, then it will do one of two things depending on whether you're in "north-up" or "track-up" mode:
In "north-up" mode, the plane icon will start to drift to the edge of the screen that marks your 6 o'clock position (so if you're headed SW, the plane icon will drift to the upper-right corner of the screen).
In "track-up" mode, the plane will drift to the bottom-center of the iFly screen, and the map will be re-oriented so that your track is "up".
In both cases, the faster you go, the closer the plane drifts toward the screen edge, to maximize visibility of what lies ahead.