23- ok, US carrier with a stop in the Caribbean ... Caribair and Trans Caribbean were long gone, but as I recall they both hubbed at San Juan (SJU), which seems like it would be a more logical stop than St Croix (STX)
my next thought was that the comment about “more affordable than the traditional airlines” most likely pointed to a post-deregulation carrier, since most if not all the former supplementals that tried their hand at scheduled service (World, Arrow, et al) ran single-class jets ... but this was about the time that Pan Am was trying to re-reinvent itself; was this flight perchance a PA 72S that then continued IAD-JFK?