A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robin Stuart
Date: 2019 Oct 24, 06:23 -0700
A flat map is not a problem provided it is the right one. On a gnomonic projection great circles are straight lines. Meridians of longitude will therefore be straight but parallels of latitude are curved since (except for the equator) they are small circles. These features are present in the chart which appears to be a gnomonic projection centred near Howland Island. There is a slight complication that bearing angles cannot be plotted directly by simply using a protractor. I have not checked but I assume that if the author knew enough to use a gnomonic projection, he knew enough to adjust the angles.
As has been discussed many times on Navlist, just inspecting the cocked hat can be misleading. It would be far more useful to plot a confidence ellipse if that is possible given the data,