[derstosstrupp]

I have thought about this as well. It might be sufficient when the azimuth is further east or west to apply the correction for “spherical transfer” to the resulting line of position before you advance it. My first Sunline is normally a latitude line, so no issue there, but my second one in the afternoon after three hours is of course about 45° shifted, so that would need such a correction.

I should add that I don’t typically use the German running fix method of plotting both lines of position from the second observation. I understand that method, but I find it much easier to simply just DR the first LOP physically on the map.

Of course I might be all wet on the above, and it may likely be invalid, but at least it’s close enough for government work. The litmus test for me is 10nm. If my intercepts are larger than 10 nm using my DR as AP, then I worry.