sexdriven - For long-range flights, it does not make good sense to have a Contingency Fuel policy which is based solely upon some % figure of the total 'Trip Fuel' and therein it's maddness (
though I'll admit that it's a nice feeling, from a piloting pespective) to
regularly arrive at ones destination with all, or most, of ones contingency fuel still in the tanks; So there's a re-clearance procedure, designed to reduce the Trip Fuel (
and, as it's a % function of the Trip Fuel, to also reduce the Contingency Fuel).
That said, occasionally it might not work out, e.g. in-flight you find you need more (
contingency) fuel than has been allowed for, e.g aircraft is heavier than the load sheet suggests, you were stuck at a non-optimum level for a long time, the head / tail winds are not as forecast, etc.
In that instance the rules are quite specific, you either have enough fuel to do the re-clearance or you don't... and in the latter case you're going to have to come up with a 'Plan B' (
e.g. do a 'splash & dash' somewhere, assuming you're in hours to do it, etc).
In any event, when you're unable to do a re-clearance 'coz the fuel it's suggested you should have onboard simply isn't there, you're howgozit (PLOG) will have a nice audit trail of what occurred and any fuel shortfall will be readily explained (
to management) when - sitting at some intermediate airport - you're asked "So what happened?".... you'll be able to sit there, all sanctimonious, and say "
We'll I took what you told me to and it wasn't enough, for these reasons - refer to PLOG - so might I suggest you go speak to Ops / NCC / Dispatch?!"
As a CYA, might I therein suggest that you keep copious notes wrt fuel remaining / flight levels / head-tail winds on your PLOG.
Saving fuel, be that for range / payload purposes, or simply to save money is sensible (
it's a commercial operation after all and is all part and parcel of what pays our wages) but fuel planning is
NOT an exact science and I'm all for taking plenty of motion-lotion when the needs dictate and therein I will happily argue the case as to why I did so, when required.