Any straight line through the exact center of a chart, regardless of
direction, will be precisely a Great Circle. A line across a corner
of the chart will be the poorest representation of a Great Circle, but
still "good enough for government work." Probably as close as the
average GA pilot can hold a course, anyway.

I decided to finally test this. I drew Great Circle segments on top of
the straight line path. The difference is small but significant.

That's a very interesting chart, Kyler.

I can't see the red GC line very well except against the dark brown of
the higher elevations; but it seems as if the two lines are only about
a line-width apart. I wouldn't consider that "significant," but of
course that's a personal judgment.

My reaction is the opposite of yours: I'm impressed by how well the
straight line follows a Great Circle.

Can you tell me how many nautical miles separate the two lines, at the
point of widest divergence?

Thanks. vince norris