NavList:

The KAL 007 event was a tragedy of errors. The heading selected in the 747-200 failed to intercept and capture the normal inertial guided navigation system. Left in 'heading select' the 747 flew straight, and entered prohibited airspace. Not strictly a rhumb-line, because no drift allowance was made.

The concept of night fighters intercepting airliners then was deficient. I did the job in NATO, and the procedure was deeply flawed.

Parts of the North Pacific also used a Mercator defined track system. A glass cockpit 747 in normal navigation mode (LNAV) would cut corners and never actually be on track when following waypoints at the same latitude. If ATC permitted time saving short-cuts, this would normally be done by entering 'direct to' in the flight computor, rather than engaging 'heading select.'

Regarding flights in small aircraft at latitudes of less than 60° ot so, it makes no difference what the projection is. At flight speed, you've only got one compass, and one map, maybe with no line on it, so just get on with it before the fuel runs out.