by Hagar » Sat Sep 03, 2016 10:44 am
Aircraft with the question mark were most likely created for FS2004 (FS9) which has no thumbnail images on the selection menu.
To fix it simply paste a screenshot of the aircraft in JPEG format into its appropriate texture folder. The image must be named thumbnail.jpg. Size of the image doesn't matter but the smaller the better. Default size is 256 x 128 pixels.
If the aircraft has more than one variation you will need a thumbnail for each texture folder. Check the texture folders of any default aircraft to see how it's done.