Rod, Are we talking about the default King Air that comes with XP? In general, a lot of aircraft will have a source selector, like the default King Air that comes with X-Plane. To answer your question, the GPS in the default King Air is actually a simplified FMC...not fully realistic, but it "works." Here's what to do: 1. Enter your waypoints as needed 2. Change your selected source to GPS (see red box on left of picture below) 3. Take-off and intercept the path of your route. After take-off you can push the "LOC" button (see red box on right of picture below) This is a quick and dirty without using up too much time to explain. Hope this helps some!