Currently, the planned route is shown as a series of straight lines between waypoints. They should be great circle routes instead.

 

When waypoints are a long way apart (e.g. oceanic) it looks like you're off track when you refer to the map but in fact you're right where you should be.

One possibility may be to add an option to use the Lambert conformal conic projection that is often used by aeronautical charts. 

 

Alternatively, This StackOverflow post shows how to use turf.js with MapBox to plot great circles.

Edited May 5, 20251 yr by fatboyfat_uk