Aviation
Here we have a lineup of helicopters - an MH 6 ‘Little Bird’ used for inserting and extracting special forces soldiers from tight locations such as rooftops, a Hughes 500 police helicopter, an EC 130 fire rescue helicopter, and an EC 135 air ambulance helicopter. Just kidding, but the pattern does look to be based on the Hughes 500 series which is also the derivative for the MH 6.
Bruce Highland got his start in Army aviation, and he would have trained in a TH 55 Osage, which was a militarized Schweizer helicopter. He earned his Warrant Officer bars, and then latereled over to MI. In the series of action adventure novels, he’s often flying something.
Your author also is a pilot. I do not have a rotorcraft rating, have had some experience with helicopters, mostly flying in the back of Blackhawks. And left seat once - that’s a story for another day. I don’t fly much these days but I still remain active in the aviation community, and will in fact be assisting in a ground school class presenting a couple of course segments to PPL candidates soon. And just maybe, some lucky students may be the recipients of some shiny new helicopters.