Yup, noticed the proximity versus ground targets for a while now, most especially when F8'ing to a fixed target, then doing an F12 disconnect and doing a wander
around the area. Also, when a CAS mission kicks off, it waits until you hit waypoint 4 before the targets are "beamed in."
But the parked aircraft seem more like, well, aircraft.
They seem to have a mission to sit on the ramp and chill, and hit their 1 waypoint until a certain time, as all aircraft flights do.
I'm gonna keep rummaging, but I think they are done on the fly, when a mission is generated for the player. Finding those missions in memory would rock, but is
a bit more complex then I am able to handle.