I do love my Dad (ahem, I always love him) when he sends me 'interesting' questions. Tonight's was
"When we fly from London Heathrow to Vancouver assuming we use the great circle, how far north does it get?"
Ah, now calculating a great circle is easy. I used this for a rough and ready answer, complete with pretty picture. It's approx 4111 nautical miles if you're interested.
Calculating the most northerly point was a bit more trial and error. To save myself brain ache I simply put in latitude and longitude from the previous programme (LHR = 51°28'39"N 00°27'41"W, YVR= 49°11'38"N 123°11'04"W into this programme and asked for a waypoint 'half' way round, ie at 061°W. OK, not terribly scientific but the approx answer is 68° 40' North.
I'm sure there are far more clever people out there who will do this standing on my head but, how does that look Dad? It's a bit more accurate than my husband's suggestion of holding a piece of string between London and Vancouver over a globe. Mind you, probably similar result!