Narrative:

I came on duty at early am. Flew two legs and had an 'airplane swap'. Accepted an airplane with left main tank fuel gauge on MEL. Flew it two more legs. Both times, the fuel tank was filled (9600 pounds). Both times it was verified full by maintenance and a notation, although not strictly required, was entered in the book. The last leg, from bos to roc, was scheduled to depart at xx:30. By this time I was tired and wanted to 'get with it.' I still believed however, that I was being careful. I went into operations and signed the release for fuel of 19000 pounds. The airplane was full, but boarding began late at xx:15. I returned to the airplane, where the first officer told me that the mechanic had been on board and said he would either verify the fuel by 'drip stick', or we could use a fuel log to calculate how much we had burned and ad a known quantity. This satisified me that maintenance was aware of the MEL and would take proper action. I turned my attention to checklists, etc. The gate agent brought the fuel slip at the last min before pushback, and it said 19000 pounds. This satisfied me. I meant to verify the fuel with maintenance on the headset during pushback, but the headset turned out to be inoperative and we pushed with hand signals. We took off uneventfully. The airplane was slightly heavy on the right side, but not to a particularly unusual degree. After we were en route, I noticed that the left tank (the inoperative one) was decreasing at the same rate as the right one. I wondered if it could, in fact, be working. It read approximately 1800 pounds lower than the right. I got the fuel slip out for closer inspection. The fueler said he had added 2100 pounds per side, but the meter readings showed he only added 330 gal, or 2211 pounds total. Now I was convinced that we had, in fact, taken with 9600 pounds in the right tank, the gauge for which was working, and 7500 pounds in the left, which was approximately the amount of fuel left in each tank after the previous leg. That would put us 2000 pounds low on fuel, but we would still land with 10000 pounds, more than enough for legal reserve and alternate. The problem was balanced. If we did, indeed, have 2000 pounds difference between tanks, we exceeded the lateral difference limitation of 1000 pounds. I was very angry with myself for failing to identify this problem before leaving the ground. I was let down by the fueler and by maintenance allowed myself to be rushed, and failed to verify, verify, verify. It is a lesson in the area of delegation of jobs, also. I should have tripled checked by watching them stick the tanks, and insisting on another logbook entry to that effect, as we had on the previous two legs. I honestly believe fatigue to be a factor in this misjudgement. Our airline is scheduling longer duty days for crew utilization, but the legal limits don't take into account normal human factors.

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Original NASA ASRS Text

Title: MLG TKOF WITH AN APPARENT 2000 LB SHORTAGE OF FUEL IN THE LEFT WING.

Narrative: I CAME ON DUTY AT EARLY AM. FLEW TWO LEGS AND HAD AN 'AIRPLANE SWAP'. ACCEPTED AN AIRPLANE WITH L MAIN TANK FUEL GAUGE ON MEL. FLEW IT TWO MORE LEGS. BOTH TIMES, THE FUEL TANK WAS FILLED (9600 LBS). BOTH TIMES IT WAS VERIFIED FULL BY MAINT AND A NOTATION, ALTHOUGH NOT STRICTLY REQUIRED, WAS ENTERED IN THE BOOK. THE LAST LEG, FROM BOS TO ROC, WAS SCHEDULED TO DEPART AT XX:30. BY THIS TIME I WAS TIRED AND WANTED TO 'GET WITH IT.' I STILL BELIEVED HOWEVER, THAT I WAS BEING CAREFUL. I WENT INTO OPS AND SIGNED THE RELEASE FOR FUEL OF 19000 LBS. THE AIRPLANE WAS FULL, BUT BOARDING BEGAN LATE AT XX:15. I RETURNED TO THE AIRPLANE, WHERE THE F/O TOLD ME THAT THE MECH HAD BEEN ON BOARD AND SAID HE WOULD EITHER VERIFY THE FUEL BY 'DRIP STICK', OR WE COULD USE A FUEL LOG TO CALCULATE HOW MUCH WE HAD BURNED AND AD A KNOWN QUANTITY. THIS SATISIFIED ME THAT MAINT WAS AWARE OF THE MEL AND WOULD TAKE PROPER ACTION. I TURNED MY ATTN TO CHKLISTS, ETC. THE GATE AGENT BROUGHT THE FUEL SLIP AT THE LAST MIN BEFORE PUSHBACK, AND IT SAID 19000 LBS. THIS SATISFIED ME. I MEANT TO VERIFY THE FUEL WITH MAINT ON THE HEADSET DURING PUSHBACK, BUT THE HEADSET TURNED OUT TO BE INOPERATIVE AND WE PUSHED WITH HAND SIGNALS. WE TOOK OFF UNEVENTFULLY. THE AIRPLANE WAS SLIGHTLY HVY ON THE R SIDE, BUT NOT TO A PARTICULARLY UNUSUAL DEG. AFTER WE WERE ENRTE, I NOTICED THAT THE L TANK (THE INOPERATIVE ONE) WAS DECREASING AT THE SAME RATE AS THE R ONE. I WONDERED IF IT COULD, IN FACT, BE WORKING. IT READ APPROX 1800 LBS LOWER THAN THE R. I GOT THE FUEL SLIP OUT FOR CLOSER INSPECTION. THE FUELER SAID HE HAD ADDED 2100 LBS PER SIDE, BUT THE METER READINGS SHOWED HE ONLY ADDED 330 GAL, OR 2211 LBS TOTAL. NOW I WAS CONVINCED THAT WE HAD, IN FACT, TAKEN WITH 9600 LBS IN THE R TANK, THE GAUGE FOR WHICH WAS WORKING, AND 7500 LBS IN THE L, WHICH WAS APPROX THE AMOUNT OF FUEL L IN EACH TANK AFTER THE PREVIOUS LEG. THAT WOULD PUT US 2000 LBS LOW ON FUEL, BUT WE WOULD STILL LAND WITH 10000 LBS, MORE THAN ENOUGH FOR LEGAL RESERVE AND ALTERNATE. THE PROB WAS BALANCED. IF WE DID, INDEED, HAVE 2000 LBS DIFFERENCE BTWN TANKS, WE EXCEEDED THE LATERAL DIFFERENCE LIMITATION OF 1000 LBS. I WAS VERY ANGRY WITH MYSELF FOR FAILING TO IDENT THIS PROB BEFORE LEAVING THE GND. I WAS LET DOWN BY THE FUELER AND BY MAINT ALLOWED MYSELF TO BE RUSHED, AND FAILED TO VERIFY, VERIFY, VERIFY. IT IS A LESSON IN THE AREA OF DELEGATION OF JOBS, ALSO. I SHOULD HAVE TRIPLED CHKED BY WATCHING THEM STICK THE TANKS, AND INSISTING ON ANOTHER LOGBOOK ENTRY TO THAT EFFECT, AS WE HAD ON THE PREVIOUS TWO LEGS. I HONESTLY BELIEVE FATIGUE TO BE A FACTOR IN THIS MISJUDGEMENT. OUR AIRLINE IS SCHEDULING LONGER DUTY DAYS FOR CREW UTILIZATION, BUT THE LEGAL LIMITS DON'T TAKE INTO ACCOUNT NORMAL HUMAN FACTORS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.