Great circle formulae, True cource and actual heading

As others have pointed out, it's all there on my web-site, but you
have to piece it together.

http://williams.best.vwh.net/avform.htm


Many thanks for a great page. Truly a great piece of work.

I have looked at it and found the mag var code.

I am just surprised that they vary so much depending what model is been
used.

What model is the best? And also it seems that by the poles the calculation
are somewhat wrong, is it just my imagination?

Sims