I do not know how people on Western hemisphare deal with that, but for me in Hungary it seems FS9 stores magnetic declination values with revers sign. In fact I do not know how to get declination values for any points, it is not displayed. I can retrive them via FS Navigator only.I am interested based on which database Microsoft assigned the values to the simulated Earth. Declination is changing continuously and checking against real and precise databases I could not find a year for which values in FS would match real-life figures. Do you have any idea? And do you know how I could retrieve magnetic declination of a certain location from FS9 from a custom developed program?Please reply me directly if you have some useful answer!Gabormailto:[email protected]

At least in the US, on the real-world aeronautical databases and charts the magnetic variation is only updated every five years. The last update was 2000, the next update will be in 2005.I am assuming that MSFS is using the values Jeppesen gave them in 2003 (or whatever date the "navdata" was finalized) for FS2004. So the magnetic variation should still be from 2000.

The flight simulator uses a MAGVAR table in drive:Program FilesMicrosoft GamesFlight Simulator 9SceneryBASEScenerymagdec.bgl to provide global magvar. This table is quite old.However, the scenery files use a MAGVAR value that is fairly recent. If you open a file with AFCAD, you will see the MAGVAR values. AFCAD reverses the values from the usual rule, East is least, West is best. If you are using AFCAD, it may seem the values are reversed.If you are designing scenery, use the newest values. If you are only flying, the simulation will use the table regardless of external NAV data information.W. Sieffert

Thanks for the fast and useful answer. It is in fact a bit frightening that there are different kind of magnetic variation information on top of each other in FS.Anyhow if I understand it correctly, if I am planning routes based on magnetic direction I should be better using the old, but consequent gobal table. I would like my C program (navigation data calculator for Russian planes) to read these values from the table directly. Do you have information on the structure of this magdec.bgl file? I have the waypoint (geographical) coordinates and I would like to get the magnetic variation. These waypoints could be any points on Earth.Gabor

Many airports in the UK got new runway numbers this year because of the constant change. Caused a little confusion over the R/T but generally when smoothly :()

Any idea in which structure SceneryBASEScenerymagdec.bgl stores magnetic declination values?

Search the AVSIM library for magmsa.zipW. Sieffert

>Any idea in which structure SceneryBASEScenerymagdec.bgl>stores magnetic declination values?Thanks for Bill, I could figure out the answer. Here it is:After the 136 byte header the bgl file contains the magnetic declination pseudodegree values in a table of 181 columns and 360 rows. The table contains latitudes in coulmns from South Pole to North Pole (left to right), Longitudes in rows up to down from Greenwhich towards the East. We have a one degree resoultion for the values: 1 2 3 89 90 91 179 180 180 S90* S89* S88* ... S01* S00* N01* ... N88* N89* N90*1 E000*2 E001* ...180 E179*181 E180*182 W179* ...359 W178*360 W179*Stored values are 2 byte signed integer "pseudodegrees":magnetic declination = (pseudodegree / 32768) * 180Gabor