[MobiusHorizons]

I think a lot of aviation navigation is by named waypoints on charts. I am definitely not an expert, but I believe some of these would be visually identifiable in good weather, or even identified by radar transponders. Compas deviations would certainly be an issue, but I believe are important to account for even in much more populated areas. Aviation does use gps now, but many of the previous systems still exist and are quite clever. The ILS system this is based off of is such a system.