.-01-.02 XTE is actually incredibly accurate. That is what I see between waypoints that could be 100's of nm apart. That's from wind drift,etc., but as you approach a waypoint it will pretty much put you directly on it. But don't think you can use an airport waypoint as a runway to put you down on the numbers. An airport waypoint is almost always the center of the airport. The Trio will control your ascent, cruise altitude, course and descent rate, but in all reality you need to fly the plane the last 10 miles or so to the runway. (So you can say you actually flew the plane!) I believe iFly is going to add features to bring you to a given runway, and that will even enhance the function of an autopilot. I generally disengage the ap when I am calling out 10 miles out during the last part of my descent.