Bose-x
According to your numbers the climb to FL120 costs you an extra 6 min flight time and saves 10lts of fuel over a 2 hour trip.
Using a typical UK fuel price (£1.40/ltr) the climb saves you £7/hour, this has to be balanced with the cost of 3 min of airframe & engine costs.
My guess is that if you are paying the UK price for fuel you will be better of by about £ 4/hour at FL120 but as soon as you uplift duty free fuel you would be better off at FL80.
This is of course all "still air" talk and a good look at the wind charts could change the whole picture.
Last edited by A and C; 8th January 2008 at 07:47.