B777-200
Flight Crew Air Transport Pilot (ATP)
Time Pressure; Human-Machine Interface; Confusion
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance; General Maintenance Action
Aircraft
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.
[Narrative contains no additional information].
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.