Magnetic variations

[davebelsey]

Tim,

In the attached screenshot:



Plymouth according to the airport info in Plan G has a magvar of 5.0, the mouse hover shows it as 3.75, and the aerodrome chart on NATS gives 3.3

I get similar results anywhere in England, but the differences rise or fall the further East or West I go.

Any ideas?

Dave.

[tim arnot]

If it is an addon airport, the variation will have been set by the developer, and may well be a figure plucked out of thin air, or pre-history, or anywhere. (I've seen some truly silly values set by developers, and even no value set). The General MagVar figure is based on the WMM-2005 data set, which is the latest and most accurate available ( http://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml )

[babba]

hello, i have a question about magnetic variation

when i connect two waipoints A and B in a country with magnetic variation 20 E for example...the heading resultant on the flight plan is comprehensive of the variation or i have to adjust the heading manually once on the plane?

excuse me for the bad english :(

[tim arnot]

Both Heading and Track are specified in Degrees Magnetic (°M), which accounts for the magnetic variation at the START of the leg. Track in degrees true is also shown on the printout if you want it.