Bonehead, you nailed it. We spent 3 days fishing in early Dec , most of that on the Airport Flat. I've never seen so many, and hard to catch, bones in my life. Finally figured it out near the end when I went to a light 15" leader, and small muted flies. Anything else spooked them. And the sharks - 5-7 footers - were all over the place, adding to the spookyness. Saw something I've never seen before, sharks working as a group o corral schools of bones.
We also found the fish on the east side to be more like bonefish, but not as many of them.