The model is not set up to use reflective texturing from what I can see.
If this is the former donationware CFS2 model now available in the CFS2 section freely, than you may be correct. The FS2002 and FS2004 models by AH are reflective, though - and some of them rather strongly!
The model does not have to have _T and _L texture extensions to properly display reflectivity...that is something that the Abacus FSDS program does.....Milton Shupe's planes have reflective texturing and do not have the _T and _L texture extensions.
Quite true - but not entirely relevent to the situation. This is a problem with the night textures, which are typically used as an overlay on the corresponding "_T" textures. The reflection remains and is displayed from the alpha channel of the "_T" texture. In this situation, some reflectivity may remain and be being displayed, but it is difficult to make out over the much much more obnoxious transparency problem!
If a "_L" texture is missing, the overlay that the FS engine is expecting (as cued by the use of a "_T" texture in the .mdl file) is missing, so that overlay effect is simply not displayed, resulting in a queer transparency issue that is not related to reflectivity or the alpha channel. The effect is most noticeable at night (which is when the light map would have played the greatest role anyway), but it can be noticed at any time of day, with its observability influenced by the reflectivity and shine programmed into the mdl materials and the alpha channel. Very glossy models with high shine and bright reflections generally suffer this problem the most.
I discovered all this while embarking upon a severe mode of reducing HDD clutter. I began going through my aircraft one by one deleting all "_L" textures that did not feature any detail I could observe. As I don't frequently fly at night, I didn't notice much... I am however a heavy user of Vit Storchs L-159B, which uses the "_T" and "_L" system. On one particularly harebrained day, I deleted the "_L" textures from there, saying to myself "To heck with the slime lights!" that were on that texture. Subsequently, I found that that model was queerly transparent during the day (though still reflective) - and as I investigated the phenomenon, with my eye tuned to it - I found traces of the effect everywhere on the airplanes I had brutalized. Needless to say, restoration necessetated a nearly complete reinstall!
You may investigate the issue yourself by removing the "_L" textures from an aircraft of your choice and observing the effects. They WILL be most noticeable at night - and may be slight to none during the day (the mdl materials influence this strongly), but on some aircraft, it is noticeable to some extent at all times.
