...untill it crashes the game.
I wouldnt have thought this be possible but it is. I added some AI to my custom made scenery (airfield) and every time it goes to take off the game decides its had enough and goes kaput. Its deffinately the AI as if i remove their flight plans and play in the same area it is fine.
The planes im using are not specific AI planes but they are not strenuous on the system at all.
Is this some sort of freak circumstance or does it regularly happen.  ???

I have found useing AI made aircraft the best way to go.allthough i have a few of mike stones aircraft in the AI list because he uses low textureing and uses gmax to build his planes.when i first started adding in AI aircraft i put one of those really supper nice boeing 747 in there and my frames droped to 2 fps.so i only use fps friendly aircraft now.i dont know if thats your problem or not maybe you should try some of the default aircraft at that airport and see what happens.allso did you add the new airport to the airport list in the ttools.that can be a problem aswell.

"One of the most common mistake made with AI is to try to fly to a non existing airport." Perhaps.

IMO, The Most Common AI mistake is trying to get planes to use airports for which there is inadequate parking i.e., the Tri-Motor requires the same size parking as the DC3.

One has to learn the relative size of AF2 parking spots as they relate to FS9 plane-size requirements. Oddly enough, Lee did not list them in his AF2 Readme file; it seems there are variables affecting the choices so it may seem prudent for him not to list them.

Bill

P.S. The next AI/AF2 offender is errors in AF2 files supplied by scenery designers. We recently checked an AF2 file for CYCD and had to correct over 30 taxiway/parking-links not being connected!