NavList:

I am pretty sure moden aircraft navigation systems use geodesic distance on WGS84 standard ellipsoid. It's only going to make a few km difference on a long flight but it's a computer not a human so they may as well, and it might add up to small fuel saving overall. I don't see any case for navigators to do calculations of geodesics on a non-spherical earth by hand, just to know that there are different geoid models. Probably worth having a sense of how much difference an oblate spheroid makes to distances and angles just to understand if a system gives different answers with different models. For example in disputed national borders it may be significant.

Bill

Yes! I remember when you mentioned this once, possibly lots of years ago. At that time, it occurred to me (and I may have commented) that this was very similar to the last days of lunars. Decades after they had ceased to be of any practical benefit at sea, they continued in grueling "master's" courses as a means or torturing students. And your description of this calculation of ellipsoidal distance in a modern course sounds very much the same. Frank Reed