I do not agree with the assertion that there would be no significance in fuel burn. The significance can be minute or it can be much greater depending on the a/c type, and distance flown.

For a short regional flight on a highly efficient a/c the significance may be extremely minute, however on a long haul flight on an inefficent 767 or 744 the significance is much more measurable to the profit or loss of that flight, particularly in light of high jet fuel prices.

The article below, which link I am re-posting, strongly suggests that the significance may be greater than perceived.

http://www.nytimes.com/2004/09/03/st...trqa_ed3_.html