Originally Posted by
aviationluver
Hello,
I noticed if you have a long leg, especially of a few hundred miles, the heading at the beginning of the leg and at the end of the leg differ by a few degrees. I'm thinking the difference is due to Magnetic Variation and the curvature of the Earth. Are there any other factors?
Thanks.
Nothing at all to do with magnetic variation. There could be absolutely no magnetic field whatsoever and your true heading will still change enroute.
Vessbot gives the best explanation as to why variation plays no part. Yes, your compass
will change, but that's just referencing another north point. If you have TH selected vs MH, you would still experience the same effect of changing headings as you traverse the globe on an extended leg.