 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B777 on an RNAV arrival executed an uncommanded turn after the crew closed a route discontinuity miles down track near the ILS while the aircraft was close to the next and already active arrival waypoint.
| Attributes | |
| ACN | 1141451 |
| Time | |
| Date | 201401 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.TRACON |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B777-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | Pilot Not Flying Relief Pilot |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types |
Narrative:
While on the RNAV arrival crew closed a discontinuity just prior to ILS in the FMC while approaching a waypoint early on the RNAV arrival. The aircraft began an uncommanded right turn which the crew noticed immediately and corrected back onto the arrival by disconnecting the autopilot. The next waypoint was in fact the next point in the FMC. ATC commented on our right turn but we were already correcting and reissued clearance.automation failure. Three crewmembers verified that the FMC was programmed correctly for the arrival. Uncommanded turn occurred after discontinuity closed and close to the waypoint. Unable to explain why that would happen. Crew debriefed event and recalled an fcif describing uncommanded turns while editing FMC close to a waypoint. Not sure if this is related.
Original NASA ASRS Text
Title: A B777 on an RNAV arrival executed an uncommanded turn after the crew closed a route discontinuity miles down track near the ILS while the aircraft was close to the next and already active arrival waypoint.
Narrative: While on the RNAV arrival crew closed a discontinuity just prior to ILS in the FMC while approaching a waypoint early on the RNAV arrival. The aircraft began an uncommanded right turn which the crew noticed immediately and corrected back onto the arrival by disconnecting the autopilot. The next waypoint was in fact the next point in the FMC. ATC commented on our right turn but we were already correcting and reissued clearance.Automation failure. Three crewmembers verified that the FMC was programmed correctly for the arrival. Uncommanded turn occurred after discontinuity closed and close to the waypoint. Unable to explain why that would happen. Crew debriefed event and recalled an FCIF describing uncommanded turns while editing FMC close to a waypoint. Not sure if this is related.
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.