The FASTBOAT Patch page.

[Suhiir]

They certainly circle the target hex and fire into it, and given the number of weapons on the aircraft and the number of times they fire one would expect them to obliterate everything in the target hex. Sadly this has not been the case in my experience. I used them several times in Vietnam era scenarios and counted myself lucky if they caused one or two casualties to a squad and only recall a single instance where one destroyed a vehicle. But as with anything I'm sure others have seem them decimate regiments single-handedly.