Originally Posted by
PEI_3721
“… mostly academic unless you are really performance limited.”
But isn't the point that you need a good estimate of weight in order to determine if you are performance limited ?
If the estimated weight is in error, so too threshold speed for the landing distance calculations. Speed, is a squared term in energy, thus for ‘stopping’ it could have a significant effect on achieved performance.
You already have a good estimate of weight given to you by estimated fuel on arrival plus your ZFW.
You are over thinking the need for that accurate of a weight - on my aircraft type (for a given set of conditions) we require a factored landing distance of 1818m at our maximum landing weight and would approach at 157kt.
At our usual landing weight (which is over 20,000kg less) we require 1700m and would approach at 149kt.
Knowing our exact landing weight isn’t necessary, nor practical. If we were trying to land on a runway that was only 2000m long, a more accurate weight would be beneficial, but not critical.