It really has been appreciated. Let me give some feedback on the winds issue for the interest of anyone following this topic.
Mutt made the point about the winds varying by season, and suggested I break it down into quarters.
I have got the results from a flight planning system for the route and they show clearly the difference that the varying seasonal winds make (there was a different routing each season to minimise the effect of headwinds); this is for a B777 and using 85% reliability historic winds:
Jan-Mar
Headwind 39 knots. Fuel needed 98,167 kgs. Flight time 15:05.
Apr-Jun
Headwind 38 knots. Fuel needed 92,073 kgs. Flight time 14:23.
Jul-Sep
Headwind 8 knots. Fuel needed 85,220 kgs. Flight time 13:29.
Oct-Dec
Headwind 42 knots. Fuel needed 93,989 kgs. Flight time 14:39.
Not for operational use of course, and I am reminded that Murphy's Law would mean that the first time when this is done for real, the winds would be at 99% of historical values not 85% . . . . . .
