Narrative:

Flight delayed over 1 hour due to thunderstorms over mco/ground stop for western departures. Following normal pushback final weights received (paper copy/auto upload to FMC). The auto-load was accepted into perf init page of FMC and takeoff data request sent using the auto-load indicated takeoff weight. After receiving paper copy of takeoff data (mco runway 18L) as well as uploaded takeoff data for FMS I compared paper final weights/paper takeoff data/uploaded takeoff data and found the uploaded ZFW (140.0) was not the same as the paper ZFW (137.4) (final weights). +2600 pound difference.I sent an ACARS msg to load planning (lp) as we taxied out asking for clarification (what is our 'real' ZFW) and received no response. I then radioed mco ops and asked them to call lp for us via telephone to clarify which ZFW was correct/why the error... They declined (tried to re-direct us by simply repeating the ZFW shown on our paper copy. I used ACARS to again request new final weights and again received the same paper ZFW (137.4) and different auto-load ZFW (140.0).our flight was now very late; and with no help impending from the company (in fact help declined by mco operations) captain and first officer had been discussing the situation and decided to proceed with takeoff using the greater (conservative) 140.0 ZFW and also discussed possible out-of-trim condition on takeoff. We had previously preplanned max takeoff thrust for the weather. This was used and takeoff was accomplished with no problems.in cruise flight I sent ACARS msg to dispatch requesting assistance to find our actual ZFW for cruise altitude selection (our FMS was indicating lower altitude capability than planned) as well as accurate of landing data when we approached the destination airport.dispatch msg indicated 're-release back to the original release could have been the issue' which made no sense and left us again not knowing what our real ZFW was.I sent another msg explaining that I wanted to know if this was an automation error of the auto-load software and was told that the dispatcher 'just got off the phone with the chief pilot. He explained anytime it's less than planned will upload planned since conservative unless you request new weights.' this guidance to my understanding is just plain wrong... The purpose of the final weight upload is to put in the accurate ZFW/takeoff weight based on actual bag count/pax count/etc. As I don't consider a multi-thousand-pound-error 'standard operating procedure' I again inquired if this was an auto-load software issue that could potentially effect more than us and was told 'yes;' and the dispatcher now stated he was also filling out a report...my main concerns:-potential systemic FMS auto-load software issue...wrong ZFW loaded affecting C.G. (Even after additional attempt to call for ZFW/auto-load perf init data a second time.-failure of lp to respond to request for help.-subversion attempt of mco operations 'to just get us airborne.' they refused to acknowledge our need to speak to lp.-inaccurate chief pilot guidance to dispatcher concerning 2400 pound ZFW error.

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Original NASA ASRS Text

Title: B737 First Officer reported difficulty in obtaining final weights before takeoff at MCO.

Narrative: Flight delayed over 1 hour due to thunderstorms over MCO/ground stop for western departures. Following normal pushback Final Weights received (paper copy/auto upload to FMC). The auto-load was accepted into PERF INIT page of FMC and takeoff data request sent using the auto-load indicated takeoff weight. After receiving paper copy of takeoff data (MCO Runway 18L) as well as uploaded Takeoff data for FMS I compared paper Final Weights/paper Takeoff Data/uploaded Takeoff Data and found the uploaded ZFW (140.0) was not the same as the paper ZFW (137.4) (final weights). +2600 pound difference.I sent an ACARS msg to Load Planning (LP) as we taxied out asking for clarification (what is our 'real' ZFW) and received no response. I then radioed MCO ops and asked them to call LP for us via telephone to clarify which ZFW was correct/why the error... They declined (tried to re-direct us by simply repeating the ZFW shown on our paper copy. I used ACARS to again request new Final Weights and again received the same paper ZFW (137.4) and different auto-load ZFW (140.0).Our flight was now very late; and with no help impending from the company (in fact help declined by MCO operations) Captain and First Officer had been discussing the situation and decided to proceed with takeoff using the greater (conservative) 140.0 ZFW and also discussed possible out-of-trim condition on takeoff. We had previously preplanned Max Takeoff thrust for the weather. This was used and takeoff was accomplished with no problems.In cruise flight I sent ACARS msg to dispatch requesting assistance to find our actual ZFW for cruise altitude selection (our FMS was indicating lower altitude capability than planned) as well as accurate of landing data when we approached the destination airport.Dispatch msg indicated 're-release back to the original release could have been the issue' which made no sense and left us again not knowing what our real ZFW was.I sent another msg explaining that I wanted to know if this was an automation error of the auto-load software and was told that the dispatcher 'just got off the phone with the Chief Pilot. He explained anytime it's less than planned will upload planned since conservative unless you request new weights.' This guidance to my understanding is just plain wrong... the purpose of the Final Weight upload is to put in the accurate ZFW/Takeoff weight based on actual bag count/pax count/etc. As I don't consider a multi-thousand-pound-error 'standard operating procedure' I again inquired if this was an auto-load software issue that could potentially effect more than us and was told 'yes;' and the dispatcher now stated he was also filling out a report...My main concerns:-Potential systemic FMS auto-load software issue...wrong ZFW loaded affecting C.G. (even after additional attempt to call for ZFW/auto-load PERF INIT data a second time.-Failure of LP to respond to request for help.-Subversion attempt of MCO operations 'to just get us airborne.' They refused to acknowledge our need to speak to LP.-Inaccurate Chief Pilot guidance to dispatcher concerning 2400 pound ZFW error.

Data retrieved from NASA's ASRS site 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.