Having added an airport, no amount of adjusting with FlattEx of AFCAD will alter the heights of runways etc. The aircraft is permanently up to its wings in soil!Will I need to amend the .bgl file, and if so, how do you open them?

Can we assume this is a completely new airport you have created and not a revision of an existing, default one?I so, the procedure I normally use is to flatten the area I will be using (the entire airport property) first, using something other than FlattEx.Several programs can do this and my favorite is FSTflatten by Steve Greenwood. You can get it in a small suite of utilities named fstutilities.zip at:http://home.earthlink.net/~smgreenwood/welcome.shtmlClick on the resources tab - FSTFlatten is the last item.When using the flatten and Afcad programs, be sure you are working with the same units - preferably meters.Then you should be able to create your airport in Afcad, being sure you keep the airport elevation and the runway(s)elevations the same as the flatten you created.This procedure works for me - Good luck.