NZFF

This is a recently released resource from NZCAA. Although for real world ops there is no reason it can’t apply to operations in the the virtual world. MSFS, with its enhanced scenery features, would be ideal.
Not the best name for a navigational technique really.

Dead reckoning

Give it a go if you want to add a little realism and purpose to your x country flights.

That is an excellent guide

Thanks for the link
Mike