Exactly, when all the units appeared I saved the game so I don't have to start up with the airshow and much to my surprise the B zodiac WILL allow you to unload but the C zodiac......NOT SO MUCH
Fortunately, if you can get the Vipers to that end of the island they can thin the opposition a bit and then you can put the wet guys back in their boat and get to shore..... or at least that's what I managed to do
So "be creative" folks. Now that everyone knows what to do...... enjoy!