601 viewpoint
This was always the problem, never matching the FMS and real fuel.
In general the fuel gty gauge is more accurate. However they took perhaps 10 mins to settle down following refueling.
So we would set the FMS to the eventual gauge fuel quantity.
Get to TOC, and thern reset the FMS fuel qty, to match gauge fuel.
In the 601, the L and R fuel gauges would wander up and down, and show imbalance at start of cruise, but mostly when left alone would rebalance themselves before TOD.
We had biased data set for planning, so mostly had no major errors on fuel remaining. BUT there was still always a 500Lbs or so extra fuel on board after landing.
Currently on G550, the FMS learns more about the aircraft, but still we are 500Lbs or so up after landing based on even our TOD estimates. Progress.
glf (x 601)