I got talking to Vaqueroaero one time about this film - he was actually going to meet Larry Hagman. I'm sure he won't mind me quoting his PM on the subject:
'[Hagman] summed up making 'Deadly Encounter' as "Totally nuts"!
Apparently most of the stunts he was in the 500, but had no idea how dangerous the stuff was until afterwards. As he pointed out they never got the shot on the first take. If you've seen the movie, the part where they fly through the shed by the docks took 5 takes to get the desired shots. He's not a rated pilot, but shook the stick for some of the scenes. He said he really struggled to keep it in a straight line.'
!