If you, as the pilot flying, reach around behind and have a look at the large book(s) that say 'Aircraft Flight Manual' aka AFM, you will find, in the performance section, a series of charts/graphs that will lead you in the right direction, to provide a series of scenarios for max range, max endurance, min flight time, etc, and in addition, many modern (and a few older) FMS's also give this information, depending on aircraft weight...and the more clever ones, winds aloft, among other parameters.
I have lost count of the number of times I have referred new(er) First Officers to the AFM, and the information they gained thereby is...priceless.
In fact, several have mentioned...'gosh, there is a LOT in here, I wonder why the company didn't tell us about it?'
I wonder also, for the info is so basic that every pilot should KNOW this, from the old gray (but new to the type) Captain to the fuzzy cheeked First Officer.
In the Lockheed TriStar, it has a bright orange or yellow cover, which says 'Lockheed California Company' on the front and EVERYTHING you need to know about performance issues or indeed aircraft systems/limitations/operational procedures are included in the two volumes.
A great deal of time and expense were invested in producing these manuals, and pilots really do need to have a look, every once in awhile.
Saying it another way...RTFB.
PS: I speak here of Lockheed/Boeing/Douglas aeroplanes, perhaps Airboos machines are a tad....ah,lacking.
Dunno.
