757/767 Drag factor

[oceancrosser]

This may have been covered before, but here goes

On the Ident page on the 757/767 FMC there are 2 factors, Drag Factor and FF (Fuel Flow) factor. Now the FF I know how is found, but how is the Drag Factor found? Is it calculated by maintenance?, the result of flight tests as a sticker in one of our aircraft suggests or...

appreciate any info

regards,

Oceancrosser

[mutt]

The drag factor and fuel factors are derived from the Boeing aircraft performance monitoring program based upon trend analysis. The inputs for the program are collected either automatically through ACARS or by the crew completing a monitoring form.

Mutt