...well not being an FSX user I can only speak from what I hear or read, but Airport Design Editor would be the main engine for the basics of your new airport..
" It takes it's inspiration from the excellent AFCAD2 developed for FS9 by Lee Swordy. ADE does for FSX what AFCAD does for FS9 and adds support for new FSX features such as fences and jetways."
You will need a Flatten program to ..well..flatten areas for your new airport and also an Exclude program to ..yes....exclude all those unwanted trees and buildings etc......in FS9 I use Flatten.bgl and Exclude.bgl. Not sure if they work with FSX but sure to be similar utilities for FSX..........
Other bits and pieces will have to be installed on your PC to make all these things work properly together but all that will no doubt be explained in the Help files which come with the various downloads........
Try here http://www.scenery.org/graphical_editors.htm for the download...the basic version is 1.0 but there is an update link built in to it which you can access after installing........( think)
READ the instructions BEFORE installing eh!
...best I can offer but best of luck with it all...........commoner
