It appears that a flattened area is automatically imposed by FS2004 around all runways and taxiways. There does not seem to be a way to adjust the area flattened with the Regional scenery files - FLnnnnnn, ABnnnnnn, APnnnnnn. Does any one know of a place to adjust this default flatten area?Dick Boley

I believe changing the airport and runway elevations in the XML (AFCAD2) will fix this. scott s..

If the question is "Can the airport base be modified?", with respects to size, then the answer is yes. This can be done in SBuilder by making a new polygon to take out whatever portion(s) deemed necessary. Or to add in additional areas. Other programs may accomplish the same, my experience is with Sbuilder. This would make a new BGL file which then gets activated and layered through the Scenery library.Hope that helps a little, if that was the question.Lance

Hello Dick,I read your post at Luis' forum, and suppose that you mean the airport reference altitude, although I could be mistaken.We had discussed this matter extensively and it had seemed that everyone got the point, so maybe I am on the wrong track here.There are 2 elevation values for an airport, independently of the altitude mesh.The FL (flatten) for the entire airport so that all the ground is level.And the AP (airport) reference altitude that determines the AI aircraft level and also places the runway, taxiway, and aprons at that altitude. Note that this is not the AB (airport background) that only draws the grass on the ground.To modify the elevation values for an airport requires changing both FL and AP altitudes. Both.FL is easy to change, either appending to SBuilder, or creating a new flatten.There are different ways to change AP, but not by AFCAD. There is no "DeleteAirportReferenceAltitude" command in BGLComp, so we cannot write this into a new AFCAD file.So, to change this, either get Jacky Brouze's JABBgl (in the library) that specifically writes a new value to the default AP, and this is my preferred method since it is pretty simple and does not entail any great effort.Or, please search this forum for Dick Ludowise's very clever solution where a new file is written that only specifies a new altitude. This simple and small bgl is then placed well below the default AP file and is read first, thereby setting the altitude before any later files are loaded.Is this what you need?Best regards.Luis

Sorry that I was not clear. I do not want to change the altitude. I want to change the flattened area around the runways and taxiways. I have removed the airport from the flatten file (FLnnnnnn) and the ABxxxxxx file. However, a flattened area remains around the runway and taxiways using an AFCAD built airport. I want the natural mesh to determine the the elevation up to the edge of these elements. The amountdistance of "forced" flatten around the runway and taxiways seems fixed for all airports. AFCAD documentation mentions this in its documents. There it is said that only elevations above the runway/taxiway elevation are forced to be flattened. However, I find this not to be true since mesh depressions are also flattened. There is no description on how to change this function.Dick near 5G8

DickI once found the flatten value you are looking for in FS9 but can't seem to locate it at the present time. Holger and I was posting on this same subject many months ago. I will continue to search for that post which explained where FS9 draws the flatten from.In the mean time the runway has no affect on the flatten. Only the taxiway and aprons have the default generic flatten boundry.When I work with the AFCAD program I never use a seperate flatten file for the entire airport boundry. I allow the taxiway and the aprons to use their default flatten so any swells in the mesh remain intack. The runway is a different issue. I create a small apron with the AFCAD program and hide it under the runway. The size of the apron helps to flatten the mesh if the apron is the right size (not to big). This helps in getting the mesh around the runway to remain in a default state. Do not place a taxiway at the very beginning (entrance point) of the runway or it will flatten the mesh before the threshold.There are additional elevation issues that may have to be worked out (see previous post) but those airport/runway elevations have to due with AI/User airplane wheel contact to surface both on startup and airborne.

Jim,Thanks, the info is indeed correct. I would have expected the runway to also be a flattened area as well.Confusing...If you come across a reference on how to adjust the taxiway/apron auto-flatten area please let me know. [email protected],Dick