Narrative:

After reviewing paperwork for our flight; I contacted dispatcher. We had a normal briefing. I had one question about the tow line on the front page of the performance paperwork. On that line; both our actual tow was printed as well as the limiting weight which; in this case was 641;000I. The four pilots had never seen this 'I' before so I asked dispatch about it. He gave me a very detailed and informative explanation of this and expressed his surprise that it was there. He mentioned in passing that this could potentially affect our standardized computerized aircraft performance (scap) and he was glad I brought it to his attention. Fast forward to just prior to departure after we receive our final weights. The first officer attempted to insert all the data into the box. It took everything until he tried to put the v-speeds in. The FMC would not take either vr or V2. It would replace the scap-generated vr and V2 with its own number with the annotation of 'vr min' and 'V2 min' next to the speeds. This caused a further delay in our flight. We requested new data through ACARS to insure we had the right parameters. We used different flap settings and nothing helped. While the first officer continued to solve the problem; I contacted dispatch about the problem. After several minutes describing the issue with our new dispatcher; the first officer deleted all the data from the perf/init page and the T/O page in the FMC and reinserted everything. At this point; he was able to insert and the FMC kept the scap-generated v-speeds. I alerted dispatch to this fact; and we were all satisfied it was safe to continue. Whether the 'I' number did indeed affect the scap or whether it was a 'stray electron;' I don't know. I found it strange we had such problems that none of us had ever encountered before and thought it worthwhile to bring it to your attention.

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Original NASA ASRS Text

Title: A B777 FMC would not accept the takeoff Standardized Computerized Aircraft Performance (SCAP) data because of an aircraft takeoff weight annotation 'I'; so the auto-entry data was cleared and reentered manually.

Narrative: After reviewing paperwork for our flight; I contacted Dispatcher. We had a normal briefing. I had one question about the TOW line on the front page of the performance paperwork. On that line; both our actual TOW was printed as well as the limiting weight which; in this case was 641;000I. The four pilots had never seen this 'I' before so I asked Dispatch about it. He gave me a very detailed and informative explanation of this and expressed his surprise that it was there. He mentioned in passing that this could potentially affect our Standardized Computerized Aircraft Performance (SCAP) and he was glad I brought it to his attention. Fast forward to just prior to departure after we receive our final weights. The First Officer attempted to insert all the data into the box. It took everything until he tried to put the V-speeds in. The FMC would not take either Vr or V2. It would replace the SCAP-generated Vr and V2 with its own number with the annotation of 'Vr min' and 'V2 min' next to the speeds. This caused a further delay in our flight. We requested new data through ACARS to insure we had the right parameters. We used different flap settings and nothing helped. While the First Officer continued to solve the problem; I contacted Dispatch about the problem. After several minutes describing the issue with our new Dispatcher; the First Officer deleted all the data from the Perf/Init page and the T/O page in the FMC and reinserted everything. At this point; he was able to insert and the FMC kept the SCAP-generated V-speeds. I alerted Dispatch to this fact; and we were all satisfied it was safe to continue. Whether the 'I' number did indeed affect the SCAP or whether it was a 'stray electron;' I don't know. I found it strange we had such problems that none of us had ever encountered before and thought it worthwhile to bring it to your attention.

Data retrieved from NASA's ASRS site as of April 2012 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.