Narrative:

The loadsheet was given to us for an on time pushback and the first officer loaded the numbers in the performance computer and CDU per normal operations. No discrepancies were noted at this time, however, I thought that the v-spds seemed lower than what they should have been (clue #1). The passenger count on the loadsheet and the flight attendant passenger count matched. Pushback and engine start were normal, followed by a short taxi to runway 1 for takeoff. Takeoff with flaps 5 degrees and reduced thrust of 85% per the performance computer were normal. We initially set the throttles at 90% and left them there. This actually helped our takeoff performance but also probably helped hide the weight discrepancy. Since it was the first officer's leg I did not notice anything unusual about the takeoff or aircraft performance. The first officer later informed me that the aircraft seemed to fly like a heavier aircraft than we had calculated, but that he thought the trim setting was a little off (clue #2). Climb and cruise seemed normal, however, the descent profile we flew was a little behind the required descent profile to make crossing altitudes (clue #3). Hou approach turned us inside downtown hou, from a left downwind for runway 12R, and slightly high. We were having trouble slowing the aircraft, getting it configured and descended on the approach with flaps 30 degrees as briefed (clue #4). We elected to use flaps 40 degrees, but still could not meet the stabilized approach criteria, so we asked for runway 4. It took several attempts to request runway 4 from approach control before we were answered. They sent us to hou tower and they were unable to give us runway 4 so we elected to go around. This probably helped our performance since the fuel used on the go around lowered our gross weight for the subsequent approach and landing on runway 12R. On the second approach to runway 12R we both noticed that the aircraft was unusually nose high for flaps 30 degrees and that more power than usual was required to maintain our calculated approach speed (clue #5). I rechked the flap setting at least twice to make sure the flaps were set correctly. We actually flew 10 KTS faster than our calculated approach speed in order to have better control over our pitch attitude. Once during the approach I noticed the stall indicator appear at the top of the HUD viewfinder and then go away (clue #6). At this point we knew that something was wrong, but even with all the clues we did not know what it was. The approach ended with a hard landing. At this point, it finally dawned on me that perhaps our weights were wrong on the loadsheet therefore wrong in the performance computer and CDU. When we checked the loadsheet we realized that the agent in msy had not added the passenger and cargo weight to the oew and had used the oew as the ZFW. This resulted in a 22000 pound error in our performance calculations.

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Original NASA ASRS Text

Title: B737-300 FLC USES THE WRONG GROSS WT FOR THE ACFT PERFORMANCE CALCULATIONS, RESULTING IN A HARD LNDG AT HOU, TX.

Narrative: THE LOADSHEET WAS GIVEN TO US FOR AN ON TIME PUSHBACK AND THE FO LOADED THE NUMBERS IN THE PERFORMANCE COMPUTER AND CDU PER NORMAL OPS. NO DISCREPANCIES WERE NOTED AT THIS TIME, HOWEVER, I THOUGHT THAT THE V-SPDS SEEMED LOWER THAN WHAT THEY SHOULD HAVE BEEN (CLUE #1). THE PAX COUNT ON THE LOADSHEET AND THE FLT ATTENDANT PAX COUNT MATCHED. PUSHBACK AND ENG START WERE NORMAL, FOLLOWED BY A SHORT TAXI TO RWY 1 FOR TKOF. TKOF WITH FLAPS 5 DEGS AND REDUCED THRUST OF 85% PER THE PERFORMANCE COMPUTER WERE NORMAL. WE INITIALLY SET THE THROTTLES AT 90% AND LEFT THEM THERE. THIS ACTUALLY HELPED OUR TKOF PERFORMANCE BUT ALSO PROBABLY HELPED HIDE THE WT DISCREPANCY. SINCE IT WAS THE FO'S LEG I DID NOT NOTICE ANYTHING UNUSUAL ABOUT THE TKOF OR ACFT PERFORMANCE. THE FO LATER INFORMED ME THAT THE ACFT SEEMED TO FLY LIKE A HEAVIER ACFT THAN WE HAD CALCULATED, BUT THAT HE THOUGHT THE TRIM SETTING WAS A LITTLE OFF (CLUE #2). CLB AND CRUISE SEEMED NORMAL, HOWEVER, THE DSCNT PROFILE WE FLEW WAS A LITTLE BEHIND THE REQUIRED DSCNT PROFILE TO MAKE XING ALTS (CLUE #3). HOU APCH TURNED US INSIDE DOWNTOWN HOU, FROM A L DOWNWIND FOR RWY 12R, AND SLIGHTLY HIGH. WE WERE HAVING TROUBLE SLOWING THE ACFT, GETTING IT CONFIGURED AND DSNDED ON THE APCH WITH FLAPS 30 DEGS AS BRIEFED (CLUE #4). WE ELECTED TO USE FLAPS 40 DEGS, BUT STILL COULD NOT MEET THE STABILIZED APCH CRITERIA, SO WE ASKED FOR RWY 4. IT TOOK SEVERAL ATTEMPTS TO REQUEST RWY 4 FROM APCH CTL BEFORE WE WERE ANSWERED. THEY SENT US TO HOU TWR AND THEY WERE UNABLE TO GIVE US RWY 4 SO WE ELECTED TO GO AROUND. THIS PROBABLY HELPED OUR PERFORMANCE SINCE THE FUEL USED ON THE GAR LOWERED OUR GROSS WT FOR THE SUBSEQUENT APCH AND LNDG ON RWY 12R. ON THE SECOND APCH TO RWY 12R WE BOTH NOTICED THAT THE ACFT WAS UNUSUALLY NOSE HIGH FOR FLAPS 30 DEGS AND THAT MORE PWR THAN USUAL WAS REQUIRED TO MAINTAIN OUR CALCULATED APCH SPD (CLUE #5). I RECHKED THE FLAP SETTING AT LEAST TWICE TO MAKE SURE THE FLAPS WERE SET CORRECTLY. WE ACTUALLY FLEW 10 KTS FASTER THAN OUR CALCULATED APCH SPD IN ORDER TO HAVE BETTER CTL OVER OUR PITCH ATTITUDE. ONCE DURING THE APCH I NOTICED THE STALL INDICATOR APPEAR AT THE TOP OF THE HUD VIEWFINDER AND THEN GO AWAY (CLUE #6). AT THIS POINT WE KNEW THAT SOMETHING WAS WRONG, BUT EVEN WITH ALL THE CLUES WE DID NOT KNOW WHAT IT WAS. THE APCH ENDED WITH A HARD LNDG. AT THIS POINT, IT FINALLY DAWNED ON ME THAT PERHAPS OUR WTS WERE WRONG ON THE LOADSHEET THEREFORE WRONG IN THE PERFORMANCE COMPUTER AND CDU. WHEN WE CHKED THE LOADSHEET WE REALIZED THAT THE AGENT IN MSY HAD NOT ADDED THE PAX AND CARGO WT TO THE OEW AND HAD USED THE OEW AS THE ZFW. THIS RESULTED IN A 22000 LB ERROR IN OUR PERFORMANCE CALCULATIONS.

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.