I've started doing a lot of VFR flights generating my own paper flight plans using real-world aeronautical charts. I can obviously work out my true tracks from the charts and also the local magnetic deviation (e.g 2

I'm pretty sure it does. It's not that difficult really. FSX does a lot of pretty accurate spherical geometry and magnetic variation is is just a simple correction.

I've started doing a lot of VFR flights generating my own paper flight plans using real-world aeronautical charts. I can obviously work out my true tracks from the charts and also the local magnetic deviation (e.g 2

No.. it does not incorporate magnetic deviation. Magnetic deviation is a compass error caused by metal in the airframe.. and magnetic fields from avionics, etc.It does incorporate magnetic variation... just look at VOR compass-rose, and runway orientation.

No.. it does not incorporate magnetic deviation. Magnetic deviation is a compass error caused by metal in the airframe.. and magnetic fields from avionics, etc.It does incorporate magnetic variation... just look at VOR compass-rose, and runway orientation.

Your explanation does not jibe with this:http://en.wikipedia.org/wiki/Magnetic_declination

Your explanation does not jibe with this:http://en.wikipedia.org/wiki/Magnetic_declination

I believe that it does.. First paragraph from that link:

Magnetic declination is the angle between magnetic north (the direction the north end of a compass needle points) and true north. The declination is positive when the magnetic north is east of true north. The term magnetic variation is a synonym, and is more often used in navigation

Deviation and Variation are two different things..

Brett is absolutely correct

Brett is absolutely correct:TVMDCT - True headingV - VariationM - Magnetic headingD - DeviationC - Compass HeadingT V M D CGoing left to right, "west is best, east is least" YOU ADD WEST, and SUBTRACT EASTGoing right to left, just the oppositeSorry, dbl post

The confusion is because of the terms used. Magnetic variation is the difference between true north and magnetic north. Compass deviation is the affect the airframe has on the compass reading. FSX does model magnetic variation, but as has been said, it's fixed at a time before the sim code was frozen prior to release. In the real work, magnetic variation is fluid, changing over time.

I recall having read that the magnetic variation in FSX is set to the year 2005 and this never changes regardless of the date setting in FSX.I understand that mag var can be set in custom airports that can reflect more recent mag vars i.e. to reflect runway number changes so everything appears in sync and correct.Best wishesSteve

The confusion is because of the terms used. Magnetic variation is the difference between true north and magnetic north. Compass deviation is the affect the airframe has on the compass reading. FSX does model magnetic variation, but as has been said, it's fixed at a time before the sim code was frozen prior to release. In the real work, magnetic variation is fluid, changing over time.

Thanks for that Bill - It indeed does seem to be a matter of "terminology".BTW - I use a small gauge when placing objects which displays the "true" heading with the Mag Var factored in. It reads the fixed variation which ships with FS from the file named magdec.bgl which is found in the Scenery/BASE/scenery subfolder.

The date/period you need to look for if you want your real life charts to fit with the world in FSX is Feb 2005 .Aces used the 02-2005 cycle of data from Jeppesen.Another nifty tool if you can't find region charts with declinations for your flight but need to know the declination, if any:http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclinationIt let's you get the declination value for any point on earth at a date of your choosing.. Perfect for simming in a world stuck in 2005.I was in doubt about mag dec in fsx myself after having returned to flight simming this week after almost a year's hiatus.But I just tested, it to confirm it for myself yet again, I looked up a 2005 declination map, picked an area with a huge value, (20 degrees west declination in this case.)Loaded up one of the airports around that area of declination (sao paulo), turned my plane on the parking space to point direct to magnetic south and checked the map.And there it was, proof positive, I would have been flying 20 degrees off course if I wanted to go to true south on the map.A bit sciency of me I know but for those who want to "peer review"/check my experiment in detail :) :-I checked this map: http://upload.wikimedia.org/wikipedia/comm...on_Map_2005.pngIt doesn't show actual magnetic lines, but lines of corresponding declination (confused me at first.)-I picked the area around Sao Paulo, Brazil because of its huge declination which should be obvious in FSX, if FSX really uses the data they had from 2005 to its fullest and because I knew I would find Sao Paulo's itl airport in that area of South America :)-Loaded up fsx, parked the default Cessna on a parking spot on Guarulhos, went to map, put in the gps coordinates for my parking spot into the tool at http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination to get a more precise number than the small compressed map gives and to verify I was reading the map correctly, chose 15 feb 2005 but anything around that date will do, while magnetic variation is a constantly mutating map irl it doesn't wander around so fast that it matters if you put in feb 1st 2005 or feb 20th 2005 as far as I know and 1 or 2 degrees declination isn't very important to me as I fly hands on planes mostly so my course wont be rock steady "fmc" straight anyway.-The geophysics tool gave me a declination of 19

I recall having read that the magnetic variation in FSX is set to the year 2005 and this never changes regardless of the date setting in FSX.I understand that mag var can be set in custom airports that can reflect more recent mag vars i.e. to reflect runway number changes so everything appears in sync and correct.Best wishesSteve

My understanding is the magnetic variation is set globally by the file magdec.bgl. Although the SDK suggests that magvar can be set locally for airports and navaids, my understanding is the such local settings have no effect.This seems sensible. If the magvar is changed at a specific location then there would be a discontinuity between the local and global values.

My understanding is the magnetic variation is set globally by the file magdec.bgl. Although the SDK suggests that magvar can be set locally for airports and navaids, my understanding is the such local settings have no effect.This seems sensible. If the magvar is changed at a specific location then there would be a discontinuity between the local and global values.

Correct. Magdec.bgl provides a world grid with variation values within each cell. It can be updated but I don't know any for FSX. There exists one for FS9 that IIRC is set for 2005. airports know nothing about variation, although the runway designation number is used in naming various elements, so if you change the number (regardless of actual variation in the grid) you have to change all other airport elements that relate to that number. If you use an airport or approach diagrams from the web, there could be some difference in magnetic courses shown vs those used in the sim. Same thing if you use current AIRAC data in an FMS database.The exception is with VORs. VORs have a magdec attribute and that is used to compute the radial that an aircraft receives. This can result in a mag course shown in the GPS being different from the VOR radial that you are flying.Note that at least in NE Canada, VORs and airport runway designations are set to true and FSX follows this. This is done due to the extreme variation around magnetic north. I also have charts for McMurdo in Antarctica that are referenced to "grid north". FSX uses magdec though.I don't know which, if any, aircraft FMS or nav systems allow setting to true north in high latitude situations.scott s..