On Feb 2, 9:46 pm, Mxsmanic wrote:
Hardly a misconception. The "sweet spot" for airliners is quite high,
and airlines like to be there in order to use the smallest amount of
fuel for a given distance.

MX,
Duh.No one is arguing that a jet uses less fuel up high.It is the
reason why that is in question.You are making a HUGE misconception
about the reason why.In fact, it could be said that you are thinking
backwards.By your reasoning, A jet would never have a service ceiling!
Explain to us what a "sweet spot" is.Why is it that you feel the
airlines dont take into account TIME when doing the preflight planing.


I've looked that the fuel required to cover a given amount of ground,
and it's much lower at high altitudes.

OK MX, here is the "Given amount of ground" thing again.Think real
hard about what you are saying and why you seem to think time doesnt
factor into the equasion.If you have in fact looked into the cruise
performance charts on a airliner, what did it say in the thrust
required column.In other words, ignore the fuel for a minute and you
will have your answer.
KW


--
Transpose mxsmanic and gmail to reach me by e-mail.