Military AI Works

Sifting through all the tech data on model building, seems like I vaguely remember someone saying that unlike FS2002 you must texture all parts with a bitmap or the model will crash FS2004. Is this true?

Looking at Nick's bitmap, I see He is using a DTX3 with alpha channel.
Isolating the alpha I see a couple of squares in the upper left of the bitmap. Is this the texture that is being used for glass or if the first question is untrue, He's using diffused base material no bitmap for glass?

Up to FS2004 you could 'colour' a part using a material only if you wanted to.
With FSX all parts must have a texture or they will show up black.

Alpha - can be used for either reflectivity or transparency. So its quite likely the areas you found are for glass (transparency).
An alpha with a material is treated as transparency.
An alpha without a material is treated as reflective.