ACR FLT BURNED PART OF THEIR BALLAST FUEL.

Narrative

ON A FLT FROM ALO-STL WE HAD TO DECLARE A FUEL EMER. I HAD FUELED IN STL TO ALO AND RETURN AND ALTERNATE ARPT WAS NEEDED FOR ALO BUT NOT FOR STL. DUE TO THE PAX LOAD OF ONLY 8 BOOKED BACK TO STL; I HAD TO LAND WITH A MINIMUM OF 600 LBS OF FUEL FOR BALANCE PURPOSES WHICH IS APPROX 1 HR OF FUEL IN RESERVE. WE ALSO HAD A TAILWIND OF APPROX 60 KTS. WITH NO KNOWN DELAYS OR EXPECTED THERE WAS NO REASON FOR US TO EXPECT TO LAND WITH LESS THAN 600 LBS (1 HR) OF FUEL AND WHAT WE SAVED BECAUSE OF THE TAILWIND. WE WERE TOLD TO HOLD AT ATLAS (THE STL 323 DEG R/400) AND A EFC OF XA51Z WE ENTERED HOLDING AT XA22Z. WE DEPARTED THE HOLD AT XA51Z AND PROCEEDED TO THE ARPT 40 MI INBND ON THE STL 323 DEG R AND THEN OUTBND ON THE STL 115 DEG R. WE WERE ABOVE THE CLOUDS VMC (THE CEILING WAS APPROX 7000' AND 5 KM) AND ON DOWNWIND ABEAM THE ARPT WHEN I WAS LISTENING TO THE CTLR TALKING TO OTHER ATC ABOUT THE LENGTH OF THE LEGS AND FINALS. AT THIS POINT WE HAD APPROX 450# OF FUEL LEFT AND ADVISED APCH THAT I WAS FUEL CRITICAL. AT THAT POINT HE TOLD ME THAT THERE WAS A 51 KM FINAL AND I SAID I COULD NOT DO IT; THAT IT WAS TOO LONG; SO HE ASKED ME IF I WAS DECLARING AN EMER. I TOLD HIM THAT I GUESS I HAD TO BECAUSE I COULDN'T GO THE LONG FINAL. HE OFFERED ME RWY 24; BUT BECAUSE OF THE WINDS I SAID NO. THEN THE CTLR TOLD ME TO EXPECT 30L BEHIND AN ACFT ON 14 KM FINAL. WE GOT ON THE GND WITH NO PROBS AND NOTHING ELSE WAS SAID. THE FUEL GAUGES SHOWED 340# AT SHUTDOWN. AFTER RECREATING THE TRIP AND FUEL BURN I CAN ACCOUNT FOR ALL BUT 44# OF FUEL AND THIS COULD BE IN THE GAUGE ERROR.