Narrative:

We were scheduled to fly a B737-800 from iah to pdx. This was the first and only leg of the first day of a 3-DAY trip. Due to aircraft maintenance problem, we were equipment-swapped to a B737-900. We eventually pushed 1 hours 31 mins late. All preflight inspections, checklists and routines were normal in the new airplane with the exception that we did not receive a pre departure clearance through ACARS. We obtained our clearance from clearance delivery. At the time of push, we did not receive a hard copy of our weight and balance from the gate agent. We had the expectation to receive our copy via the aircraft ACARS and printer, both of which were working normally. Ramp control told us to expect runway 8 for departure. We asked him if he could send us the latest 'numbers' for runway 8 since we normally receive runways 15L&right data. During taxi, we did not receive the load. Ground control then cleared us to runway 15L for departure. During taxi, I requested the final performance initiation and takeoff data via the ACARS. We received both data successfully through data uplink. While in the run-up pad for runway 15L, tower asked us to contact company. We did so and found out that they thought we may have departed the gate without one of our fuel caps. It was determined by maintenance that we could depart without the captain if in fact we were missing one. At this time we still did not receive any hard copy of our load via the printer. We departed iah without incident. Once en route to pdx, we received 3 SELCAL messages to contact our dispatcher. The captain had all conversations with the dispatcher. He passed that load planning wasn't sure which load we had and we replied that we only had the uplinked data. The dispatcher then sent us the correct load to our printer. The load and the conversations with the dispatcher confirmed that we departed iah with inaccurate data and in fact uploaded data calculated for our first plane a B737-800 and not a -900. I believe the difference in the zero fuel weights was about 8000 pounds lighter. The correct data was then entered into the plane's FMC and the flight continued to destination. Personally, my fault was that I forgot that we needed the hard copy on board prior to departure. I was under the assumption that the uplinked data would be good enough. The captain and I reviewed our fom and confirmed that we did need to have a copy on board. We also determined that our errors included that we could not verify passenger count, load confign and most importantly the actual aircraft data. Supplemental information from acn 572778: the first officer typed in several different runways and the data finally loaded, but the company pilot weight manifest did not come off the printer like it usually does. The lesson I learned was to not run the taxi checklist until we have a hard copy of the weight manifest. That would have prevented this incident.

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Original NASA ASRS Text

Title: A B737-900 FLT CREW DEPARTS WITHOUT A PROPER WT AND BAL AT IAH, TX.

Narrative: WE WERE SCHEDULED TO FLY A B737-800 FROM IAH TO PDX. THIS WAS THE FIRST AND ONLY LEG OF THE FIRST DAY OF A 3-DAY TRIP. DUE TO ACFT MAINT PROB, WE WERE EQUIP-SWAPPED TO A B737-900. WE EVENTUALLY PUSHED 1 HRS 31 MINS LATE. ALL PREFLT INSPECTIONS, CHKLISTS AND ROUTINES WERE NORMAL IN THE NEW AIRPLANE WITH THE EXCEPTION THAT WE DID NOT RECEIVE A PDC THROUGH ACARS. WE OBTAINED OUR CLRNC FROM CLRNC DELIVERY. AT THE TIME OF PUSH, WE DID NOT RECEIVE A HARD COPY OF OUR WT AND BAL FROM THE GATE AGENT. WE HAD THE EXPECTATION TO RECEIVE OUR COPY VIA THE ACFT ACARS AND PRINTER, BOTH OF WHICH WERE WORKING NORMALLY. RAMP CTL TOLD US TO EXPECT RWY 8 FOR DEP. WE ASKED HIM IF HE COULD SEND US THE LATEST 'NUMBERS' FOR RWY 8 SINCE WE NORMALLY RECEIVE RWYS 15L&R DATA. DURING TAXI, WE DID NOT RECEIVE THE LOAD. GND CTL THEN CLRED US TO RWY 15L FOR DEP. DURING TAXI, I REQUESTED THE FINAL PERFORMANCE INITIATION AND TKOF DATA VIA THE ACARS. WE RECEIVED BOTH DATA SUCCESSFULLY THROUGH DATA UPLINK. WHILE IN THE RUN-UP PAD FOR RWY 15L, TWR ASKED US TO CONTACT COMPANY. WE DID SO AND FOUND OUT THAT THEY THOUGHT WE MAY HAVE DEPARTED THE GATE WITHOUT ONE OF OUR FUEL CAPS. IT WAS DETERMINED BY MAINT THAT WE COULD DEPART WITHOUT THE CAPT IF IN FACT WE WERE MISSING ONE. AT THIS TIME WE STILL DID NOT RECEIVE ANY HARD COPY OF OUR LOAD VIA THE PRINTER. WE DEPARTED IAH WITHOUT INCIDENT. ONCE ENRTE TO PDX, WE RECEIVED 3 SELCAL MESSAGES TO CONTACT OUR DISPATCHER. THE CAPT HAD ALL CONVERSATIONS WITH THE DISPATCHER. HE PASSED THAT LOAD PLANNING WASN'T SURE WHICH LOAD WE HAD AND WE REPLIED THAT WE ONLY HAD THE UPLINKED DATA. THE DISPATCHER THEN SENT US THE CORRECT LOAD TO OUR PRINTER. THE LOAD AND THE CONVERSATIONS WITH THE DISPATCHER CONFIRMED THAT WE DEPARTED IAH WITH INACCURATE DATA AND IN FACT UPLOADED DATA CALCULATED FOR OUR FIRST PLANE A B737-800 AND NOT A -900. I BELIEVE THE DIFFERENCE IN THE ZERO FUEL WTS WAS ABOUT 8000 LBS LIGHTER. THE CORRECT DATA WAS THEN ENTERED INTO THE PLANE'S FMC AND THE FLT CONTINUED TO DEST. PERSONALLY, MY FAULT WAS THAT I FORGOT THAT WE NEEDED THE HARD COPY ON BOARD PRIOR TO DEP. I WAS UNDER THE ASSUMPTION THAT THE UPLINKED DATA WOULD BE GOOD ENOUGH. THE CAPT AND I REVIEWED OUR FOM AND CONFIRMED THAT WE DID NEED TO HAVE A COPY ON BOARD. WE ALSO DETERMINED THAT OUR ERRORS INCLUDED THAT WE COULD NOT VERIFY PAX COUNT, LOAD CONFIGN AND MOST IMPORTANTLY THE ACTUAL ACFT DATA. SUPPLEMENTAL INFO FROM ACN 572778: THE FO TYPED IN SEVERAL DIFFERENT RWYS AND THE DATA FINALLY LOADED, BUT THE COMPANY PLT WT MANIFEST DID NOT COME OFF THE PRINTER LIKE IT USUALLY DOES. THE LESSON I LEARNED WAS TO NOT RUN THE TAXI CHKLIST UNTIL WE HAVE A HARD COPY OF THE WT MANIFEST. THAT WOULD HAVE PREVENTED THIS INCIDENT.

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.