NavList:

Bob II, you asked:
"Are you saying the problem in general is that the math is taught backwards or in this specific case?"

A little of both but mostly the former. I don't presume to see inside the author's head. He's a guy with many tasks including this very minor column. With deadlines to meet and few readers, it makes little difference. But there is this general problem that navigators have with LHA, twisting it into something more complicated than it is, requiring all sorts of diagrams and complicated phrasing. A lot of that evaporates when we remember that LHA is a difference in longitude on the ground. And that's all it is. It's genuinely identical to a standard great circle problem where one position is the observer's latitude and longitude, and the other position is the latitude and longitude where the Sun or star is straight up. The distance between the points is identical to the zenith distance.

Frank Reed