On Feb 25, 7:28 pm, "Tony" wrote:
Don't get too tangled up in trying to find some 'optimum'. This is
instructive: do a manual calculation of what you consider might be
three or four 'likely best' routes. When you get done cranking the
numbers, you'll likely find not an important difference in your
several results. It's that old thing when we learned calculus --
nothing very interesting happens near a maxima or minima.



I normally do this stuff manually (using a computer nevertheless, but
manually entering the altitudes and ETDs), and it is a very cumbersome
process. The results are, like you say, are not dramatically
different, but I have found situations where moving the departure time
by a few hours, or planning a different fuel stop can shave off 30
minutes of flight time from a 500 mile trip. When the airplane cost is
$100/hr that could be an important consideration.

Also, in most flight planning situations we use a single cruising
altitude for the entire flight. Adjusting the cruising altitude on a
continuous basis is not handled by any software that I know of. If the
software can come up an ideal altitude profile, route profile and the
best time of departure, the pilot can then use this baseline
information from which to modify parameters to fit his specific
needs.