I have noticed that the FMC fuel remaining calculation changes significantly over the course of a flight and I was wondering why. I have 2 likely possibilities: 1) The calculation is based on zero wind and changes as wind effects are calculated 2)the calculation is based on present thrust setting and changes when thrust is adjusted.Are either of these on track or is there another (real) reason?Thanks.

"1) The calculation is based on zero wind and changes as wind effects are calculated "The FMC "blends" measured (actual) wind with wind entries made by the crew. It is a highly complicated calculation, the complexity determined by the model number of the FMC. Details of this blending are given in Chapter 9 of the Big Boeing FMC Users Guide by Bill Bulfer and ###### Gifford if you're interested.Cheers.Ian.