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B737-700 first officer reported a track deviation occurred when the autopilot dropped out of LNAV mode following a wake turbulence encounter.
| Attributes | |
| ACN | 1542569 |
| Time | |
| Date | 201805 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | BTY.VORTAC |
| State Reference | NV |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 251 Flight Crew Type 251 |
| Events | |
| Anomaly | Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Wake Vortex Encounter |
Narrative:
In cruise flight to las; we were given a descent to 31;000 ft. We reached the assigned altitude 15 to 20 miles prior to the bty VOR; which was the initial arrival segment. Our aircraft was experiencing data link comm problems; which inhibited us from doing our approach briefings and descent checklists; as we needed to receive ATIS from las. About the time I was to start my approach brief when; we encountered wake turbulence from a preceding aircraft a few miles prior to crossing bty VOR. The aircraft rolled approximately 10 to 15 degrees to the left with some moderate turbulence caused by the wake.once the aircraft returned to a stabilized attitude; the captain checked in with the flight attendants to see if they were okay. As we crossed the bty VOR; I started my arrival brief as we were given a descend via clearance. Upon completing the arrival brief I looked up to notice that the aircraft had continued past bty VOR and did not make the turn to mycal and the cws right (control wheel steering) amber was annunciated on the pfd. I put the aircraft into heading sel mode and made a turn back to the left to re-intercept the bty - mycal course. ATC inquired us about our left hand turn; we told them about the wake turbulence incident; and that we were returning on course.ensure after a wake turbulence or any aircraft upset all vertical and lateral navigation modes are reengaged and correctly tracking.
Original NASA ASRS Text
Title: B737-700 First Officer reported a track deviation occurred when the autopilot dropped out of LNAV mode following a wake turbulence encounter.
Narrative: In cruise flight to LAS; we were given a descent to 31;000 ft. We reached the assigned altitude 15 to 20 miles prior to the BTY VOR; which was the initial arrival segment. Our aircraft was experiencing data link COMM problems; which inhibited us from doing our Approach Briefings and Descent Checklists; as we needed to receive ATIS from LAS. About the time I was to start my Approach Brief when; we encountered wake turbulence from a preceding aircraft a few miles prior to crossing BTY VOR. The aircraft rolled approximately 10 to 15 degrees to the left with some moderate turbulence caused by the wake.Once the aircraft returned to a stabilized attitude; the Captain checked in with the Flight Attendants to see if they were okay. As we crossed the BTY VOR; I started my Arrival Brief as we were given a descend via clearance. Upon completing the Arrival Brief I looked up to notice that the aircraft had continued past BTY VOR and did not make the turn to MYCAL and the CWS R (Control Wheel Steering) amber was annunciated on the PFD. I put the aircraft into HDG SEL mode and made a turn back to the left to re-intercept the BTY - MYCAL course. ATC inquired us about our left hand turn; we told them about the wake turbulence incident; and that we were returning on course.Ensure after a wake turbulence or any aircraft upset all vertical and lateral navigation modes are reengaged and correctly tracking.
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.