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Guest JoeW

FSNav, FS2004, AFCAD2 and mag var.

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I have observed that the magnetic variation given in the map of FSNav isdifferent from the one shown in AFCAD2 and FS2004.If I take LEMD, for example, the default magvar shown in AFCAD2 is -3, andthe magnetic heading for runway 36L (approach course) is then359.76-(-3)=2.76. The magnetic heading given by FS2004 in map view for thatILS is 3 (ok, 2.76 rounded-off). 359.76 is the default true heading for thatrunway in FS2004.However, the magvar for LEMD shown in FSNAv is 4.7 and the approach coursefor runway 36L is shown as 4, in theory 359.76-(-4.7)=4.46 (rounded-off to 4I guess)I tend to think that FSNav is right, because if I put the plane at thethreshold of the runway 36L, and I set a magnetic heading of 4, as given byshift-z on the screen, is approximately exact, much more exact anyway thansetting a magnetic heading of 3.If I change the mag var in my modified AFCAD2 for LEMD from 3 (default) to4.7 (as considered by FSNav), it has no effect in the map view of FS2004,nor in the map view of FSNav.Does anyone know what's going on?From where is FSNav extracting the value of 4.7 for LEMD??Is this a bug in FS2004??Thanks in advance.Joaquin

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Ah, the dilemma of what magvar is doing to your system!! Or, what is the purpose of the magvar entries in AFCAD or elsewhere in the Scenery SDK!!In the past, Microsoft Flight Simulators have used a magvar table in the scenery files labelled magdec.bgl. FS2004 is no exception. When you place yourself at some location, the flight simulation software reads the magvar from the table and sets it for your location.FS2002 and earlier used magvar data that was outdated for the time period of FS2002 release. Whether FS2004 is using up to date data remains to be seen.FSNav is obviously using more up to date data than FS2004. This can be verified by various means, i.e., Recent Sectional Charts or google search the web using "magvar" or "magnetic variation".The problem now arises about what to do about the differences. FS2004 is using a static magvar from the magvar table. FSNav through updates will continue to use a magvar that changes with each update. Basically you cannot change the FS2004 static world, so it is a compromise for what you want to do with FSNav.Lastly, your findings of changing the magvar within AFCAD and seeing no change makes one wonder what the magvar entry is doing in the software. HMMM!!!W. Sieffert

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Thankyou!Well, the purpose of the magvar information is clear. To find out the correct magnetic course or approach course to a runway, which is the one you have to set in the panel of the plane to properly align with the runway.I agree with you that the MS magvar info is static and probably obsolete. I was just wondering from where does FSNav extract the information then? Because it differs from the one used by FS2004 and shown by AFCAD2, and I tend to believe that FSNav is right. FS2004 does not show magvar at all by itself, you just notice it for example in map view, when it gives you the approach for a runway with ILS.The error causes no big problems, it is just that some "accuracy-maniacs" like myself get desperate, haha!

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I wonder how static the FS9 MagVar is, given that when creating a new airport in AFCAD2 you input the MagVar, and the orientation of the runways is adjusted accordingly, not as dictated by the FS9 BGL for MagVar. Perhaps the FS9 BGL is just for the default airports, and not a representation of global magnetic variation...just my two cents worthBryan

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I do dribble sometimes. I just checked what i said in previous post, and guess what... it's wrong. Entering any MagVar value into AFCAD2 makes no difference to the airport orientation in FS9. Obviously gets MagVar info from FS9 (or FSNav if you use that). I really must check my facts before contributing to the discussion in future.Bryan

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I don't know where FS Nav get it's reading of this, but I've never found it in error. AFCAD2 on the other hand is hardly ever right. In Airport for Windows, the Mag var is not read from the program and reports that there is a difference in that and asks if you want to use what you have input or use the default. I always use my input because it can't find it and it always reverts back to "0".Joe W.

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