John Cox| Special for USA TODAY
Question: On a recent flight from London, our takeoff was delayed by an hour as the pilot and the person in charge of refueling the aircraft appeared to disagree on how much fuel we had in our plane's tanks. I saw flight engineers climbing up underneath our wings. Could you please explain how the engineers measure the amount of fuel?
—Anna, Finland
Answer: The pilots have fuel gauges in the flight deck. There are also gauges for the fuelers. These gauges should read the same. Many airplanes have a manual system as a backup.
Normally, the fuelers receive instructions on the total fuel load, and how it is to be distributed, from the airline’s dispatch office. Once they have completed the fueling, they provide the pilots with a fuel slip showing the total load and the amount in each tank. The pilots verify the information.
In your case there was a disagreement either in the total amount (more common) or how the fuel was loaded in specific tanks. In those instances, it would be appropriate for the fuelers to manually check the fuel, which requires pulling sticks from the bottom of the wing.
Q: I was recently on a flight from O'Hare to Honolulu. We were delayed for around 30 minutes and idling waiting to take off. The pilot then told us he had to go back to the gate to refuel. Does a plane burn that much fuel just sitting out on the tarmac?
— Josh Elliott, Chicago
A: If a flight is planned tightly on fuel and extensive delays occur, it can become necessary to return to the gate for additional fuel. One additional consideration: The pilot may have learned that it would still be a significant delay to take off, calculating that when the takeoff clearance arrived there would not be fuel onboard to meet the minimum requirement. So he or she elected to return early and minimize what could become an even lengthier delay.
Q: On a recent flight from North America to Asia, we detoured far north over Alaska in order to avoid volcanic activity. This detour created a fuel issue and the possibility of a refueling stop in Alaska. The captain eventually elected not to divert, but my question is: Who does these fuel calculations in such circ*mstances? Is it the flight deck crew, airline staff on the ground, or somebody else?
— Tim Riener, Fremont, Calif.
A: More than one pilot will do such calculations and then compare the results. In addition, the flight dispatcher (a critical member of the safety team) also computes the fuel requirements. Only when all agree is a decision made to stop for refueling or continue on.
John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.
