Originally Posted by
LeadSled
PS: Some of you still do not have a clue about the immutable engineering rules of "order of accuracy". The FFR (or whatever it is called this week) is to cover said "order of accuracy" or, put another way, so that you still have your engine(s) runnings touchdown ---- you DO NOT necessarily have 30 minutes of usable fuel. ALL usable fuel is the fuel except the FFR.
That'a an interesting interpretation. Can you cite a reference? You are saying that when they say 30 minutes, they don't actually mean being
sure you have enough fuel for 30 minutes?
If you burn 15 litres/h, and can gauge fuel level in 2 tanks with +/- 5 litres accuracy your margin of error is 40 minutes... 30 minutes doesn't help much. 30 minutes plus whatever uncertainty is in the reading seems like a much more likely interpretation.