[caldrail]

Any idea why at high altitudes I get these brown edges?

Does it have something to do with the visibility distance?

Yes I get that problem too. Its horrible to look at. Something less garish also happens in fly's desert crimea. The horizon is always green and it looks like you're flying over a sandpit. I did mess around with the textures to try get a result but I'm still stuck with those brown edges on the Sinai map.

It might have something to do with the video drivers though - I used to see something similar on the dx version of Red Baron way back.