I have AI A/C that like to fly into the hillside. Any ideas on a fix for this?

Where did you get the AI planes? There are a lot out there that behave like this. Older PAI planes were particularly susceptible, but they've gotten better.My first step is to take the .air file from a similar default MS plane (737, 747, or GA will cover most anything) and use that instead by editing the aircraft.cfg file's "sim=" line. This fixes most, but sometimes I have to do a cut-and-paste and create a new aircraft.cfg using the aircraft name/airline/description stuff from the AI plane and the rest of the info from a default plane.