I have been editing some of my AI flightplans and have also been swapping aircraft around. I find it strange that a select set of aircraft can act as ai, such as the default 747, F18A hornet (acceleration)to name but a few. But others just will not operate as ai and was wondering why? They do show up at all.

KeithMS uses both a User Plane and a AI Plane as the same plane. There are a couple of exceptions like the DASH 8, MD83 and PA28 which are designed by FS as AI Planes only (mapping of animated components are different).When a plane designer releases a 3rd party plane they normally specify wheather it is for the User to fly or for AI only. That is because they tweak the Flight Dynamics to either be more realistic (User Plane) or for visual behavior (AI Plane). In most cases because of the .mdl/.air/.cfg designed engineered settings a Flyable plane will not fly correctly as a AI Plane or the other way around.

Understood Jim thanks. I have a nice ch47 ai and I use it for some of my own built missions. It flies really well but is a little on the slow side. Is there any way to speed it up by tweaking a specific file? Thanks.