Narrative:

I believe there is an error in our company's ACARS runway data message system. The 4 of us have about 18 years experience on the 777 and have never seen T/O (takeoff) not possible; let alone 10 or more times. We all checked that every single entry was correct with the FM page. We asked dispatch for help and to get a 777 flight duty manager involved. Dispatch sent nine different runway data messages to us. The first was 38;400 pounds below actual final TOGW. I ACARS'ed back the large discrepancy error. He sent another for tog of 627.6 and I had to inform him again that our real final weights were 9;300 pounds higher!!!!! Then we got 3 more at 638.4 even though final weights were 636.9. But the big problem I told him is we are still getting T/O not possible on our runway data message and all of us agreed we needed to have ACARS runway data agree with dispatch calculations so could he please find out why ACARS is still showing us for the 10th time T/O not possible. Several minutes later ACARS runway data finally came up and we were able to takeoff legally but after so many different gw numbers all claiming to be correct it's hard to believe they were but the plane handled normal and fuel burn was right on. If this carrier has changed some computer system recently in relation to ACARS or dispatch runway data then an audit needs to be done because that many gross weight changes for no apparent reason is not right. I think I have most of the ACARS and dispatch messages printed although I could not print our outgoing messages to dispatch.

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Original NASA ASRS Text

Title: A B777 received nine T/O NOT POSSIBLE FMC messages because the gross weight takeoff data from Dispatch was incorrect and the Captain questioned whether a Company computer program had been modified.

Narrative: I believe there is an error in our Company's ACARS Runway Data message system. The 4 of us have about 18 years experience on the 777 and have never seen T/O (takeoff) NOT POSSIBLE; let alone 10 or more times. We all checked that every single entry was correct with the FM page. We asked Dispatch for help and to get a 777 Flight Duty Manager involved. Dispatch sent nine different RWY DATA messages to us. The first was 38;400 LBS below actual final TOGW. I ACARS'ed back the large discrepancy error. He sent another for TOG of 627.6 and I had to inform him again that our real final weights were 9;300 LBS HIGHER!!!!! Then we got 3 more at 638.4 even though final weights were 636.9. BUT the big problem I told him is we are still getting T/O NOT POSSIBLE on our RWY DATA message and all of us agreed we needed to have ACARS RWY DATA agree with dispatch calculations so could he please find out why ACARS is still showing us for the 10th time T/O NOT POSSIBLE. Several minutes later ACARS RWY DATA finally came up and we were able to takeoff legally but after so many different GW numbers all claiming to be correct it's hard to believe they were but the plane handled normal and fuel burn was right on. IF THIS CARRIER HAS CHANGED SOME COMPUTER SYSTEM RECENTLY IN RELATION TO ACARS OR Dispatch RWY DATA THEN AN AUDIT NEEDS TO BE DONE because that many gross weight changes for no apparent reason is not right. I think I have most of the ACARS and Dispatch messages printed although I could not print our outgoing messages to Dispatch.

Data retrieved from NASA's ASRS site as of July 2013 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.