Do you know how to disable jetways for AI aircraft
UT2 has an option for it.
If you are using WOAI ( not suggested, because of the fps loss due to being FS9 models ), you might have to edit all the aircraft.cfg files manually, to remove the X,Y,Z coordinates of the exits. Assuming they *have* X,Y,Z coordinates to begin with, if they are FS9 models, they shouldn't so, perhaps they are already disabled, and you can't gain any more fps, other than maybe turning off Airplane shadows.