I'm new to this so bear with me...I'm working on KRDU and can't seem to get the Flatten area to work correctly. From what I think I've learned when you draw a flatten area around an airport or wherever and then type in an elevation, that whole area becomes that elevation. Is this not correct? I have a flatten area around the airport (RDU) just for testing puposes. I only have two runways and a taxiway. anyways, there are different elevations all over the space which i supposedly had Flattened. Can anyone help?Thanks

From my experience, the runway seems to have it's own elevation - it does not simply rest on the ground. So, you would be best off to flatten the area to the same altitude as the runway.Also, objects like roads and polygons can't seems to "bend" so if they overlap a flattened and non-flattened are, they sometimes seem to disappear into the terrain. Again, it seems to help if you can keep the whole object in a flattened area.- Martin