FS 2002 Pro.
http://www.simviation.com/fsdterrainusa.htm
Isn't it a shame...!
I often download the DEM scenery mesh for some of my favourite areas, (guess where*..! Tee-Hee!), and generally, it makes a pigs ear of the default scenery...!
The scenery effect is FANTASTIC, and very realistic for the areas they represent, compared to an actual relief map of the same area...!
But...
The default airfields are either buried up to their tower tops in a deep pit, or elevated towards the clouds at the top of a hill...!
Buildings and trees are either buried in the ground, or floating in the air...!
..and water often appears half way up the beach cliff-sides...!
Roads run almost vertically up the sides of hills and mountains, (difficult for my Willy's Jeep, even in bottom gear)...!
...and as for rivers and streams...flowing up-hill?...well...!
LOL...!
...and so on...
So...
Every now and again I have to un-tick my lovely DEM mesh add-on scenery in the scenery library, to revert it back to normal, so that it doesn't look quite so daft...!
Which all goes to show that some add-on DEM scenery mesh, and the default DEM scenery mesh, often don't mix too well!
What a shame...

LOL...!
I don't suppose there is an easy way out of this, to get the best of both worlds....

Never mind, mustn't grumble...LOL...

Cheers all...

Paul.
*San Francisco to Los Angeles, to San Diego, coastal areas...!