Inspired by a comment by hupakee@lemmy.world under SurrealPartisan’s recent post in this community
The longest straight line over land is this great circle (see NeatNit’s comment here if the link isn’t working for you, sorry about that). But, of course, most great circles don’t look very straight on most maps. To correct for this, I (very roughly) got the northernmost point of the great circle and put that value into G.Projector to get an oblique equirectangular projection that treats the great circle as if it were the equator on a regular map
The base map is Wikimedia Commons’ equirectangular projection map
So yeah, as I found out this was entirely not your fault. Lemmy literally doesn’t let you post the correct link.
There is a chance that this will work though: www.gcmap.com/mapui?P=5�2'51.59"N+9�7'23.26"W-28�17'7.68"N+121�38'17.31"E&MS=wls&DU=mi
Otherwise, follow these instructions:
Go to http://www.gcmap.com/mapui
Into the “Paths” textbox, paste this:
5°2'51.59"N 9°7'23.26"W-28°17'7.68"N 121°38'17.31"EClick “Draw Map”
Result: