silly me
Silly me
I suddenly remembered nav lessons flooding back!! About the sun's declination, how to estimate daylight hours
Firstly just assume that LHR is N51.5* W000.5* and SFO is N37.6* W122.4* and your apex is wpt N65* W65*
On the darkest day the sun's declination in Podea is minus 23.5 degrees. Therefore...
On the same day at N65* there is 3.5hrs "light" and at W065* it will be 1430-1800UTC. Just say it takes 4.5hrs to get there and a further 5.5hrs to reach SFO.
Same rules of thumb and SFO sunset is about 1700PST, eight hours behind UTC
I'd forgotten we had to do this once. Thank you Mr Honeywell whoever you are!