Hi Mad Jock,
Thanks for the reply.
Maybe I'm missing something but the original question (and my question) was: what's easiest to fly: a line of Latitude or a line of Longitude.
It didn't actually mention great circles although I agree that what you say is correct regarding those.
Maybe the answer is they are both equally easy to fly? If you fly constant Lat you will be flying a rhumb line (unless it's along the equator), but it's still constant heading so no trick there. Similarly for Longitude you will be flying a constant heading but by definition it will follow a great circle track.
It's been a while since I studied Gen Nav so I may be off the mark. I appreciate any guidance.
This sounds like a potential interview question - hence my interest.
Cheers,
R.