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B767-300ER captain reported a track deviation in oceanic airspace following a wake encounter. Crew thought they were in LNAV but were actually in heading select.
| Attributes | |
| ACN | 1608803 |
| Time | |
| Date | 201901 |
| Aircraft 1 | |
| Make Model Name | B767-300 and 300 ER |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Route In Use | Oceanic |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | Cruise |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine |
| Events | |
| Anomaly | Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Wake Vortex Encounter |
Narrative:
[We] had a deviation of three miles left of course. We had been on a right slop (strategic lateral offset procedure); we had started encountering wake turbulence from an aircraft 2000 ft above. I decided to return to the track to avoid the wake. I deleted the offset and used heading to return to the track and engaged LNAV again. We were on track and LNAV. I had to go to the lav. When I returned the first officer (first officer) said we were left of track three miles. I saw we were in heading mode. I immediately turned to the route and re-engaged LNAV. I know we had verified LNAV after deleting the slop I think it's possible that I hit the heading select button as I exited the seat. Should be more aware of FMA (flight mode annunciator) indications when we change seats and positions.
Original NASA ASRS Text
Title: B767-300ER Captain reported a track deviation in oceanic airspace following a wake encounter. Crew thought they were in LNAV but were actually in HDG SELECT.
Narrative: [We] had a deviation of three miles left of course. We had been on a right SLOP (Strategic Lateral Offset Procedure); we had started encountering wake turbulence from an aircraft 2000 ft above. I decided to return to the track to avoid the wake. I deleted the offset and used heading to return to the track and engaged LNAV again. We were on track and LNAV. I had to go to the Lav. When I returned the First Officer (FO) said we were left of track three miles. I saw we were in HDG mode. I immediately turned to the route and re-engaged LNAV. I know we had verified LNAV after deleting the SLOP I think it's possible that I hit the HDG SELECT button as I exited the seat. Should be more aware of FMA (Flight Mode Annunciator) indications when we change seats and positions.
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.