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B767 flight crew reported upon coast out at resno an offset of R1 is entered and the FMC dropped the next waypoint. The FMC never caught the offset (LNAV course) and continued to turn to the right. The next waypoint had dropped from the FMC.
| Attributes | |
| ACN | 1337452 |
| Time | |
| Date | 201603 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | EGGX.ARTCC |
| State Reference | FO |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B767 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Route In Use | Oceanic |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Total 20796 Flight Crew Type 9034 |
| Person 2 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 95 Flight Crew Total 10413 Flight Crew Type 3319 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types |
Narrative:
Upon returning to the cockpit from first break; the captain provided me with the standard relief pilot change briefing. After that; he told me about an anomaly that they experienced upon coasting out at resno. Evidently; after executing R1 the FMC dropped the active waypoint and the aircraft turned right to intercept the offset in LNAV. The aircraft did not intercept the outbound course and continued to turn to the north. Both pilots recognized the anomaly and quickly intervened with heading sel keeping the aircraft well within gne limits. They noted that the active waypoint was N5430 and redirected the aircraft to N5520 which had dropped out of the FMC. After confirming that the aircraft was back on track and navigating properly; the clearance was reconfirmed with both eggx and shanwick. The three of us formally debriefed after the flight and later the captain provided us with feedback on navigation anomalies.
Original NASA ASRS Text
Title: B767 flight crew reported upon coast out at RESNO an offset of R1 is entered and the FMC dropped the next waypoint. The FMC never caught the offset (LNAV course) and continued to turn to the right. The next waypoint had dropped from the FMC.
Narrative: Upon returning to the cockpit from first break; the Captain provided me with the standard relief pilot change briefing. After that; he told me about an anomaly that they experienced upon coasting out at RESNO. Evidently; after executing R1 the FMC dropped the active waypoint and the aircraft turned right to intercept the offset in LNAV. The aircraft did not intercept the outbound course and continued to turn to the north. Both pilots recognized the anomaly and quickly intervened with HDG SEL keeping the aircraft well within GNE limits. They noted that the active waypoint was N5430 and redirected the aircraft to N5520 which had dropped out of the FMC. After confirming that the aircraft was back on track and navigating properly; the clearance was reconfirmed with both EGGX and Shanwick. The three of us formally debriefed after the flight and later the Captain provided us with feedback on NAV anomalies.
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.