I need help changing the local variation to match my 1:250 000 map. I've been looking through the BGLCOMP SDK documentation, but the only thing I can find is how to set the variation on a particular point (NDB/VOR/Aerodrome and so on).Does anyone have any experience in setting variation over a bigger area?andIf I set the variation to eg a NDB. How big area around the NDB will be affected?Arild

What do you mean with local variation, do you mean the magnetic variation?

That's right.... I'm trying to set the magnetic variation so that it matches my map. (On my map it ranges from 8

If I remember correct there is one file in the default scenery that sets the variation for the entire world, this is real world data, but it is probably a few years old. I have never tried to change this, but I just adjust the variation to the value I find in FS (although my maps sometimes show a little different value).

The file you reference is drive:Program FilesMicrosoft GamesFlight Simulator 9SceneryBASEScenerymagdec.bgl and is out-of-date. However, within the scenery files are areas to set MAGVAR.Kind of confusing, since the flight simulator uses magdec.bgl to set the magvar for the simulation. I really don't know what setting the magvar in the scenery file does for the system, if anything.It doesn't help for external systems to use updated magvar tables for their navigation, because it makes the world out of whack.W. Sieffert

So there is no way to change the variation then? I'm only flying locally within my little part of the praires so I don't care that much if the rest of the world gets screwed up....Arild

MagVar in MSFS is stationary. It will not change like real-world. The only way to fix the problem would be to completely update the magdec.bgl file.Christian Stock wrote several manuals concerning MAGVAR, see magmsa.zip.W. Sieffert