This is a new one for me. I have noticed while flying today that none of my compass headings bore any resemblance to the runway headings or to reality. At times the compass heading was as much as 140 degrees wrong. Have tried different aircraft in different regions and it is all of them. I have placed myself in positions where I have flown extensively in the real world and have a pretty good idea of what the approximate compass headings should be based on various landmarks and there is just no correspondence with reality at all.I did install a new add-on today - the DBS Terrain Map gauge but can't really believe that would cause this. Any suggestions? It pretty much makes the sim unflyable except for local hops.

Where I have seen this it is due to a scenery bgl, but have been unable to find an exact cause. I suspect it is a program bug rather than a "bad" bgl. AFAIK, the problem is seen world-wide.scott s..

I observed the same a couple of days ago. That was a flight from VTBS to EDDF in PMDG's MD11. About 60 or 70 nm northwest of VTBS all of a sudden the compass and all NDs went nuts, causing the plane to leave it's route extremely. First I thought "bug in PMDG". Therefore I stopped the flight and did the same with Level-Ds 767.Same thing, compass went crazy, but the 767 kept its route.

It will be a scenery problem, and your latest addon is likely the culprit. Disable it and see if that fixes it.

The file that is likely to be the cause is magdec.bgl It holds all the information on the magnetic variation around the FS world and if it becomes corrupt or deleted by mistake your magnetic headings will become way off. I can't remember off the top of my head where the file is supposed to be located but I've made sure on my system that its in the addon scenery / scenery folder so that it's on top of all other scenerys. Hope this help, Tom (EGCV)

The file that is likely to be the cause is magdec.bgl It holds all the information on the magnetic variation around the FS world and if it becomes corrupt or deleted by mistake your magnetic headings will become way off. I can't remember off the top of my head where the file is supposed to be located but I've made sure on my system that its in the addon scenery / scenery folder so that it's on top of all other scenerys. Hope this help,Tom (EGCV)

IF the problem is indeed related to a missing or replaced or corrupt magdec.bgl file - it can be easily restored from your install disk(s). It is located on Disk 3 in the MSGAME9.cab and should go into your \Flight Simulator 9\Scenery\BASE\Scenery subfolder.Any .cab file can be opened and files extracted from it using any good zip/unzip utility.Hope that info is useful.

The file that is likely to be the cause is magdec.bgl It holds all the information on the magnetic variation around the FS world and if it becomes corrupt or deleted by mistake your magnetic headings will become way off. I can't remember off the top of my head where the file is supposed to be located but I've made sure on my system that its in the addon scenery / scenery folder so that it's on top of all other scenerys.

This thread on the California Classic forum may be of interest:http://calclassic.proboards.com/index.cgi?action=display&board=general&thread=1714It demonstrates that the world-wide magnetic variation can be interfered with by erroneous scenery files. I have come across two such cases myself, and it takes a lot of testing to find the culprit.Interestingly, I would have thought that moving magdec.bgl from \Flight Simulator 9\Scenery\BASE\Scenery to \Flight Simulator 9\Addon Scenery\Scenery would put it at a lower priority than needed - surely it would be best positioned in a scenery folder last to load in order to take priority over anything else? If it was last to load, I would guess it would over-ride any dodgy scenery files and stick with original values . . . I haven't tried that though.John

If it means anything, I've experienced this issue before with Carenado aircraft after slewing my plane to a different location on an airport. Robert

Not that I've experienced any problems, but I found this site that has navaid updates for both FS9 and FSX (including fresh new magdec.bgl file):hsors.pagesperso-orange.fr/navaids.html

Whilst on the subject of possible magdec file errors, the one in the sim is way out of date and needs to be replaced.have a look -here-vololiberista

Thanks everyone. I started out by replacing the magdec file with a clean one from the installation disk. I put it in the standard location which is FS9/Scenery/BASE/scenery. No change. I then tried the suggestion of putting it at the highest priority, so I put it in my AES scenery file so it will always have priority. (For those of you who don't use AES, it always has to be on the top to work). ta da! --- PROBLEM SOLVED!So the cause probably is a scenery add-on and I may play around with that later to see which one it is, but as of right now, the sim is working perfectly.Thank you all very much. If I hadn't been able to get your advice I would have probably ended up having to do a complete reinstall. With all my add-ons and tweaks that would take weeks to get it back to the way it was.Thank you also to those of you who gave me links to get updated magdec and navaid files. I had no idea those sites existed. Now that I've got my basic problem solved, I am going to utilize those to update the files so they reflect present day reality and not 2003 or whenever MS got the data.I used the link provided by Vololiberista and it worked perfectly. (It may have been the same site Neumanix suggested also) A wonderful resource to keep FS9 nav information and magnetic variation up to date.You guys are awesome! :(

I've never seen magdec.bgl go bad, though I suppose you could find a mangled version somewhere. Where I have seen a bgl induced error, the compass works, just the magnetic variation is way off (over 100 degrees). I found one specific bgl file that I could remove and it went away, then I moved the bgl to a different scenery folder and the problem went away then too. That's why I don't think the problem is with the specific file, but somehow the way FS9 is loading or using it.scott s..

I've never seen magdec.bgl go bad, though I suppose you could find a mangled version somewhere. Where I have seen a bgl induced error, the compass works, just the magnetic variation is way off (over 100 degrees). I found one specific bgl file that I could remove and it went away, then I moved the bgl to a different scenery folder and the problem went away then too. That's why I don't think the problem is with the specific file, but somehow the way FS9 is loading or using it.scott s..

If memory serves (and sometime it doesn't) I have a few posts elsewhere regarding issues with the magdec file and in each case the problem was traced to one of the "updated" files which are available for download.I've not experience any problems sticking with the one which came with FS2004.Just another slant on the issue.

I'm having this problem just recently too. I haven't had time lately to check it out, but wouldn't it be interesting if all of us so recently afflicted had just bought and installed Imaginesim's new KDFW scenery?? :(

I'm having this problem just recently too. I haven't had time lately to check it out, but wouldn't it be interesting if all of us so recently afflicted had just bought and installed Imaginesim's new KDFW scenery?? :(

Imaginesim or FSDreamteam? :(