Narrative:

Flight delayed 2 1/2 hours due to late inbound aircraft. Inbound crew had written up that they were unable to download winds; a problem I had experienced on a few other occasions; possibly on the same aircraft. We were delayed further while I worked with the mechanics to reset the FMC's and ACARS and comm radios and attempted to load the winds for our flight. Ultimately we/they reset the fmcs twice to troubleshoot the correct one (left) and fix the problem. During both resets; our fmcs retained their original loading of the route; dept./dest. Airports etc. While we re-requested winds while troubleshooting the problem with maintenance. I believe this may have potentially caused a glitch on with our LNAV/FD indications on initial climb out.we loaded the BLZZR3 RNAV departure off of 15R per SOP and took off normally. LNAV engaged appropriately and commanded a left turn to intercept our course out to foxxx intersection. After raising the gear and watching the first officer's (first officer) climb profile; I noticed him continuing a sharp left turn; following the flight director; only away from our initial fix of foxxx. We both caught the anomaly and I quickly checked the box and it showed us on course to intercept our course; but the map and FD were still commanding a sharp left turn. I mentioned to the first officer I wasn't sure what was going on but to rollout and proceed back in a right turn to foxxx. We had probably turned 60 degrees when he started back to foxxx and we were handed over to departure. The controller called 'radar contact; six miles north of the airport' and gave us vectors that basically followed the rest of the SID. Rest of flight proceeded normally. We were the only aircraft in the vicinity and I don't believe there was any conflict. The controller never mentioned anything other than just giving us altitudes and vectors prior to clearing us direct to a down-line SID fix before turning us over to the next frequency.

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Original NASA ASRS Text

Title: B757 Captain reported a track deviation resulted when a malfunctioning FMC commanded an off course turn.

Narrative: Flight delayed 2 1/2 hours due to late inbound aircraft. Inbound crew had written up that they were unable to download winds; a problem I had experienced on a few other occasions; possibly on the same aircraft. We were delayed further while I worked with the mechanics to reset the FMC's and ACARS and COMM radios and attempted to load the winds for our flight. Ultimately we/they reset the FMCs twice to troubleshoot the correct one (left) and fix the problem. During both resets; our FMCs retained their original loading of the route; dept./dest. airports etc. while we re-requested winds while troubleshooting the problem with maintenance. I believe this may have potentially caused a glitch on with our LNAV/FD indications on initial climb out.We loaded the BLZZR3 RNAV departure off of 15R per SOP and took off normally. LNAV engaged appropriately and commanded a left turn to intercept our course out to FOXXX intersection. After raising the gear and watching the First Officer's (FO) climb profile; I noticed him continuing a sharp left turn; following the flight director; only away from our initial fix of FOXXX. We both caught the anomaly and I quickly checked the box and it showed us on course to intercept our course; but the map and FD were still commanding a sharp left turn. I mentioned to the FO I wasn't sure what was going on but to rollout and proceed back in a right turn to FOXXX. We had probably turned 60 degrees when he started back to FOXXX and we were handed over to Departure. The Controller called 'radar contact; six miles north of the airport' and gave us vectors that basically followed the rest of the SID. Rest of flight proceeded normally. We were the only aircraft in the vicinity and I don't believe there was any conflict. The Controller never mentioned anything other than just giving us altitudes and vectors prior to clearing us direct to a down-line SID fix before turning us over to the next frequency.

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.