FSX Default texture

I have looked and looked but I can't find what texture FSX uses for the airport background. I want to edit it so it's no longer a desert colour in autumn! Can anyone help?
There's the landclass definition excel file floating around somewhere. It should say what the image file number in the world scenery texture folder is. Holger made it.
NP, I use it to take copies of the landclass and put it over a low res bit of my Photoscenery. Then I manipltae the layer of my photoscenery to make it look right. After writing down what I did, I then apply it to the seasonal full resolution big ones.