I have some old aircraft that I am using as AI. Does anyone know how to get them to park at the gate with their gear down instead of just floating in mid air???

It sounds like your old aircraft aren't sutable for AI use. I had this problem a while back when I was using POSKY planes as AI. Try to stick with good GMAX models from FS Painter or Ai-Aardvark.

I'll second that. I had a few of these myself, but after a while I took the time to seek out FS2002 versions of the same aircraft. In most cases I've found better planes with more liveries, so floating aircraft (which always remind me of Star Wars landspeeders) are a thing of the past. (Or maybe it's the future? Waddya think, Yoda?)