Narrative:

A B747-400 in cruise on A579 on a re-dispatch flight plan to syd (via virar-nan with re-dispatch to syd) was running 6 mins behind flight plan time and 9500 pounds below flight plan estimated fuel at the re-dispatch point -- virar. Flight was 3900 pounds below minimum re-dispatch at the re-dispatch point; and with an estimated 9000 pounds remaining at syd; diverted to bne and landing with 20.9. Flight refueled and continued to syd arriving about 2 hours late. Cleared fuel at sfo was 372.2 and boarded fuel was 51918 gallons -- 355.6 pounds. Added to the 19.6 aboard we had 375.2 -- tank quantity gauges indicated 375.7. Takeoff fuel was 373.0. Flight was 1 min ahead of flight plan and 300 pounds up at first chkpoint; level at FL280. Fuel remained stable at about flight plan estimated value until center tank burnout; then indicated quantity began to drop -- 5000 pounds in next 2 hours. Calculated quantity per fuel burn stayed with flight plan. Tank versus burn score began to widen and by virar; exceeded -6.0 pounds and was continuing to increase slowly; with the tank total being the low quantity. Zero fuel weight was 400 pounds less than flight plan value; but even with a score of -9.5 at the re-dispatch point; the flight was unable to stabilize the decreasing fuel as indicated by the quantity gauges; and the fuel score was approaching 10000 pounds and decreasing about 500 pounds every 30 mins below the flight plan estimated value. The aircraft flew well; in trim with no appreciable high EPR and on mach/altitude with a ci 50 selection; didn't struggle to alter or vary the cruise mach much as would happen with an overweight aircraft. Just the gradual; unrelenting drop in the tank quantity fuel score and the inability to arrest the increasing difference in the burn versus quantity gauge total necessitated a diversion before arrival fuel became problematic.

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Original NASA ASRS Text

Title: B747-400 ENRTE TO SYD DIVERTS TO BRISBANE ACCOUNT INSUFFICIENT FUEL.

Narrative: A B747-400 IN CRUISE ON A579 ON A RE-DISPATCH FLT PLAN TO SYD (VIA VIRAR-NAN WITH RE-DISPATCH TO SYD) WAS RUNNING 6 MINS BEHIND FLT PLAN TIME AND 9500 LBS BELOW FLT PLAN ESTIMATED FUEL AT THE RE-DISPATCH POINT -- VIRAR. FLT WAS 3900 LBS BELOW MINIMUM RE-DISPATCH AT THE RE-DISPATCH POINT; AND WITH AN ESTIMATED 9000 LBS REMAINING AT SYD; DIVERTED TO BNE AND LNDG WITH 20.9. FLT REFUELED AND CONTINUED TO SYD ARRIVING ABOUT 2 HRS LATE. CLRED FUEL AT SFO WAS 372.2 AND BOARDED FUEL WAS 51918 GALLONS -- 355.6 LBS. ADDED TO THE 19.6 ABOARD WE HAD 375.2 -- TANK QUANTITY GAUGES INDICATED 375.7. TKOF FUEL WAS 373.0. FLT WAS 1 MIN AHEAD OF FLT PLAN AND 300 LBS UP AT FIRST CHKPOINT; LEVEL AT FL280. FUEL REMAINED STABLE AT ABOUT FLT PLAN ESTIMATED VALUE UNTIL CTR TANK BURNOUT; THEN INDICATED QUANTITY BEGAN TO DROP -- 5000 LBS IN NEXT 2 HRS. CALCULATED QUANTITY PER FUEL BURN STAYED WITH FLT PLAN. TANK VERSUS BURN SCORE BEGAN TO WIDEN AND BY VIRAR; EXCEEDED -6.0 LBS AND WAS CONTINUING TO INCREASE SLOWLY; WITH THE TANK TOTAL BEING THE LOW QUANTITY. ZERO FUEL WT WAS 400 LBS LESS THAN FLT PLAN VALUE; BUT EVEN WITH A SCORE OF -9.5 AT THE RE-DISPATCH POINT; THE FLT WAS UNABLE TO STABILIZE THE DECREASING FUEL AS INDICATED BY THE QUANTITY GAUGES; AND THE FUEL SCORE WAS APCHING 10000 LBS AND DECREASING ABOUT 500 LBS EVERY 30 MINS BELOW THE FLT PLAN ESTIMATED VALUE. THE ACFT FLEW WELL; IN TRIM WITH NO APPRECIABLE HIGH EPR AND ON MACH/ALT WITH A CI 50 SELECTION; DIDN'T STRUGGLE TO ALTER OR VARY THE CRUISE MACH MUCH AS WOULD HAPPEN WITH AN OVERWT ACFT. JUST THE GRADUAL; UNRELENTING DROP IN THE TANK QUANTITY FUEL SCORE AND THE INABILITY TO ARREST THE INCREASING DIFFERENCE IN THE BURN VERSUS QUANTITY GAUGE TOTAL NECESSITATED A DIVERSION BEFORE ARR FUEL BECAME PROBLEMATIC.

Data retrieved from NASA's ASRS site as of January 2009 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.