B737-400 DEPARTS WITH 3000 LBS MORE FUEL IN CTR FUEL TANK THAN CALCULATED.

Narrative

OUR FLT WAS RELEASED WITH INOP CTR TANK FLT DECK QUANTITY INDICATOR MINIMUM FUEL 22.9 AND THE FUELING FORM INDICATED 3000 LBS WAS LOADED IN CTR TANK VIA A KNOWN QUANTITY LOADED. TOTAL FUEL AT PUSH WAS 30.0 OR SO WE THOUGHT; AND TKOF WT WAS 131.3. CAPT; PNF; COMPUTED A FUEL LOG AND ESTIMATED CTR TANKS WOULD RUN DRY AT TOP OF CLB. CTR TANK CONTINUED TO FEED FOR 300 MI AT CRUISE AND WE KNEW EXTRA FUEL HAD TO HAVE BEEN IN CTR TANK. AS CTR TANK DID RUN DRY AND WE COMPUTED FUEL ON BOARD AT 18.8 (3300 LBS OVER FLT PLAN). AN ADDITIONAL PROB WAS LNDG WT AS REMAINING PROJECTED FUEL BURN WOULD GIVE US A LNDG WT OF 122.6 (1600 OVER MAX LNDG WT). WE CHANGED COURSE TO DIRECT SAC (90 MI W) DIRECT FIM FPR. WE STEPPED OUR ALTS DOWN TO INCREASE FUEL BURN WITH A TARGET OF 13.0 OVER FIM. WE MADE THAT TARGET WITHIN 200 LBS; AND FROM THAT POINT ON FOR REMAINDER OF DSCNT; APCH AND LNDG; NORMAL OPS WERE APPLIED. WE LANDED WITH 11.6 (120.4 GROSS) AND SHUT DOWN WITH 11.34 FUEL ON BOARD. MAINT FOUND INSIGNIFICANT AMOUNTS OF FUEL IN CTR TANK AND COMPLETED A NEW FUELING FORM TO VERIFY THAT CTR TANK WAS EMPTY FOR NEXT FLT. IT IS CLR NOW THAT APPROX 3000 LBS EXTRA FUEL WAS IN THE CTR RANK.