Transparent objects hide user aircraft

Hi all.

I've been following the pinned framerate thread in the FS9 forum and last night pretty well finished tidying up my user and AI aircraft in FS2004.

I branched out and started experimenting with some payware airports which were short of mipmaps, and decided to take a picture of something I've often noticed but never investigated- the effect had by some chainlink fences (see the picture below). The fence texture seems to be just a plain 8 bit bmp. The user and AI planes are identical, Microsoft's original C172.

What is it about the fence that allows FS9 AI to respond correctly to the fence's transparency while the player aircraft won't?

Cheers,

D