at day, no problems so far, but at dawning or night, the tower will be transparent as mentioned. i tried to convert the recommended files into dxt1 but without any result.
We had a look at that problem and, it doesn't have anything to do with texture format. Or, better yet, there were *two* problems at the same place, one that could be solved with the textures in DXT1, the other is the one that is still left.
And no, it's happening at day as well, but at day is not really noticeable, because you need to go very close to the tower to see it, at night it's just more visible, because the color combination is different, and contrasts with the iighted ground.
It's basically a problem of how the FS9 graphic engine handles objects which have parts with an alpha texture and the rest without it. I need to verify this, but I think it doesn't happen in FSX. If this is the case, I'm not sure we can fix it without remodeling the tower just for FS9.