If your headwinds seem to be increasing over the Montana Rockies, and your Boeing 757 FMC shows a constantly decreasing amount of Arrival Fuel (the A-310 won't show such unwelcome changes in arrival fuel?), then there is a problem. The Captain chose to descend from about FL 330 to 280 after asking ATC about lower altitude winds, and after about 10 minutes or so, the Arrival Fuel increased to a much healthier amount.
We always compare total fuel to the paper flight plan fuel at one or two fixes on short legs, more on long ones. Wasn't the Boeing FMC's PLANNED FUEL numbers very similar to Dispatch's flight plan fuel? Believe we entered known winds at numerous fixes and a cost index of about 55, and a cruise enroute temperature or such.
With a major ATC or weather re-route (June-August...even in March), we can send the new route to Dispatch and let them calculate destination arrival fuel as a back-up.
A narrowbody aircraft barely made it to a divert airport with maybe emergency fuel (!) onboard, not far short of the destination, when the uplatch check was done too quickly during climb, and hanging a bit below the gear well it caused lots of extra fuel burn. Just ONE gear door!!
