name the plane "myplane"
park the plane on the ground.
put a trigger on radio alpha, activation:
hint format ["Plane Loc: %1, Pilot Loc: %2", getpos plane, getpos planed]
unless the pilot is the center of the model, you should get different numbers there. Now you have two points in space that are related to each other. Through some simple trig, you can read the plane's pitch, roll and yaw. (well, yaw you already know through getdir)