Narrative:

On preflight the #2L fuel tank gauge was into and on mco. I asked the fueler to dipstick the 2L fuel tank after fueling to verify that the fuel quantity in 2L was correct. 2L tank had already been dipsticked prior to fueling. Later the fueler indicated to me verbally that the tank had been dipsticked, and the fuel slip indicated a balanced correct fuel load and that the tank had been dipsticked. On takeoff no unusual problems were noted. Around yyc (1 hour 20 min remaining of a 4 hour flight), the outboard 2L boost pump low pressure light came on. The appropriate pilot operating manual (pom) abnormal (ab) procedure was accomplished. About 5 mins later, the #2L boost pump low pressure light came on also. The fuel xfeed valves were opened and the #2R boost pumps were turned off in accordance with our pom. The autoplt was disconnected and the aircraft rolled to the right at about a standard rate turn. We suspected low fuel in the #2L tank causing the pump low pressure lights to come on and causing the aircraft to roll to the right, but were not positive due to the inoperative #2L fuel tank gauge. We discussed the problem with flight control and the maintenance coordinator, and they concurred a suspicion of low fuel quantity in tank 2L. Flight control reported the WX in slc on runway 34L was 2600 RVR. We had 37000 pounds of fuel in tanks one and three total and estimated it would take approximately 20000 pounds to get to slc. There was not enough fuel in tanks one and three to go to slc, make a missed approach and go to a suitable alternate. We checked WX of suitable airports en route with flight control and decided to divert into gtf which was about the top of descent distance from us. The WX in gtf was clear, visibility 20 mi, and the winds down runway 21 (headwind). The fueler and mechanic in gtf reported dipstick reading in 2L indicating 500 pounds of fuel prior to refueling. We refueled and proceeded to slc, west/O any further problems indicating low fuel. Lessons that were further impressed on me is that even though faith and confidence in the other person's capabilities and professionalism is nice to have, we need to be prepared for human fallibility. On a more practical basis, I have discussed this incident with with flight mgrs. They have assured me they would examine fueling procedures with the appropriate personnel. Supplemental information from acn 170261. We had 10000 pounds of fuel in #2R and required 3 degrees left rudder trim.

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Original NASA ASRS Text

Title: ACR WDB DIVERTS TO AN ALTERNATE ARPT IN LIEU OF DEST ARPT DUE TO LOW FUEL STATE.

Narrative: ON PREFLT THE #2L FUEL TANK GAUGE WAS INTO AND ON MCO. I ASKED THE FUELER TO DIPSTICK THE 2L FUEL TANK AFTER FUELING TO VERIFY THAT THE FUEL QUANTITY IN 2L WAS CORRECT. 2L TANK HAD ALREADY BEEN DIPSTICKED PRIOR TO FUELING. LATER THE FUELER INDICATED TO ME VERBALLY THAT THE TANK HAD BEEN DIPSTICKED, AND THE FUEL SLIP INDICATED A BALANCED CORRECT FUEL LOAD AND THAT THE TANK HAD BEEN DIPSTICKED. ON TKOF NO UNUSUAL PROBS WERE NOTED. AROUND YYC (1 HR 20 MIN REMAINING OF A 4 HR FLT), THE OUTBOARD 2L BOOST PUMP LOW PRESSURE LIGHT CAME ON. THE APPROPRIATE PLT OPERATING MANUAL (POM) ABNORMAL (AB) PROC WAS ACCOMPLISHED. ABOUT 5 MINS LATER, THE #2L BOOST PUMP LOW PRESSURE LIGHT CAME ON ALSO. THE FUEL XFEED VALVES WERE OPENED AND THE #2R BOOST PUMPS WERE TURNED OFF IN ACCORDANCE WITH OUR POM. THE AUTOPLT WAS DISCONNECTED AND THE ACFT ROLLED TO THE R AT ABOUT A STANDARD RATE TURN. WE SUSPECTED LOW FUEL IN THE #2L TANK CAUSING THE PUMP LOW PRESSURE LIGHTS TO COME ON AND CAUSING THE ACFT TO ROLL TO THE R, BUT WERE NOT POSITIVE DUE TO THE INOPERATIVE #2L FUEL TANK GAUGE. WE DISCUSSED THE PROB WITH FLT CTL AND THE MAINT COORDINATOR, AND THEY CONCURRED A SUSPICION OF LOW FUEL QUANTITY IN TANK 2L. FLT CTL RPTED THE WX IN SLC ON RWY 34L WAS 2600 RVR. WE HAD 37000 LBS OF FUEL IN TANKS ONE AND THREE TOTAL AND ESTIMATED IT WOULD TAKE APPROX 20000 LBS TO GET TO SLC. THERE WAS NOT ENOUGH FUEL IN TANKS ONE AND THREE TO GO TO SLC, MAKE A MISSED APCH AND GO TO A SUITABLE ALTERNATE. WE CHKED WX OF SUITABLE ARPTS ENRTE WITH FLT CTL AND DECIDED TO DIVERT INTO GTF WHICH WAS ABOUT THE TOP OF DSNT DISTANCE FROM US. THE WX IN GTF WAS CLR, VISIBILITY 20 MI, AND THE WINDS DOWN RWY 21 (HEADWIND). THE FUELER AND MECH IN GTF RPTED DIPSTICK READING IN 2L INDICATING 500 LBS OF FUEL PRIOR TO REFUELING. WE REFUELED AND PROCEEDED TO SLC, W/O ANY FURTHER PROBS INDICATING LOW FUEL. LESSONS THAT WERE FURTHER IMPRESSED ON ME IS THAT EVEN THOUGH FAITH AND CONFIDENCE IN THE OTHER PERSON'S CAPABILITIES AND PROFESSIONALISM IS NICE TO HAVE, WE NEED TO BE PREPARED FOR HUMAN FALLIBILITY. ON A MORE PRACTICAL BASIS, I HAVE DISCUSSED THIS INCIDENT WITH WITH FLT MGRS. THEY HAVE ASSURED ME THEY WOULD EXAMINE FUELING PROCS WITH THE APPROPRIATE PERSONNEL. SUPPLEMENTAL INFO FROM ACN 170261. WE HAD 10000 LBS OF FUEL IN #2R AND REQUIRED 3 DEGS L RUDDER TRIM.

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.