Aviation like life is full of axioms. Common sense rules to educated and guide us through work and life. One of my favorites is “the only time you have too much fuel is when you are in fire”. Now on face value insightful sage advice this statement is, but, does that mean you always take as much fuel as you can?
Now our flight planning system won’t issue a fuel load until one hour prior to the flight due to dynamic load planning or “bums on seats” changed. The issue here as crew is we show up one hour prior and by then, the fuel is already being pumped into the jet. Now to further complicate matters fuel is really expensive at some airports, including taxes, airport assessments and surcharges. So it does make sense to “ferry” some fuel into those airports. In my experience the places that have the most expensive fuel always have the shortest runways or the biggest hills around them which all put restrictions on the weight you can carry out or into them.
To figure out how much fuel you can carry you subtract the zero fuel weight, which is the weight of the aircraft plus passengers from the max landing weight. Then deduct the planned enroute fuel burn and see what is left over–THAT , minus a safety buffer and you’ll have a reasonable ferry fuel load.
The problem is, by the time I get to the jet, the “planned” fuel load–which doesn’t include the above calculation, because the zero fuel weight isn’t firm yet–is often aboard. If I do the math and find that we’ll be arriving weighing over the max landing weight, I have two choices: defuel (bad choice) before pushback or fly lower (dumb choice) to reduce the landing weight.
Both are bad options: if we defuel, that fuel must be discarded–trashed–because quality assurance standards wisely say you cannot take fuel from one aircraft’s tanks and meet the purity standards for another aircraft. So that money in the trash, plus a guaranteed delay to accomplish the defuel.
Fuel is time, to me, so nothing could be more important than more fuel if the maths supports it. Save the money safe comfortable profitable flight job done.
Unless as I noted above, you’re on fire, or more realistically, as I’ve just explained, you’re trying to achieve the best outcome as efficiently as possible. Anything less is just plane fuelishness.
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