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B777 flight crew on a trans-pacific flight reported large excursions in altitude and speed during an encounter with severe turbulence in the vicinity of kodiak; ak.
| Attributes | |
| ACN | 1406395 |
| Time | |
| Date | 201612 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZAN.ARTCC |
| State Reference | AK |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B777 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Route In Use | Oceanic |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 150 Flight Crew Total 12943 Flight Crew Type 820 |
| Person 2 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 60 Flight Crew Total 14805 Flight Crew Type 12878 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence |
Narrative:
Approaching odk [at] FL340. Message from dispatch received saying [an air carrier flight] in front of us over odk reported moderate turbulence at FL360 and descended to FL330 with a smooth ride. We then descended to 330. Passengers were seated and flight attendant advised of area of reported turbulence as a precaution. West of odk we started to encounter moderate to severe turbulence. Flight attendant told to take jump seats and ATC was advised we were unable to maintain altitude and requested block FL320-340. We received block altitude from anc center. Alt deviation of 300+ feet and airspeed changes of 40+ knots associated with the turbulence and we suspect that some altitude deviation occurred after reporting unable to maintain altitude; but before receiving block altitude of FL320-340. Speed at cruise was about 285 but with speed changes we were as high as 330 which exceeded red line by 18 knots to 240 knots on the low end!
Original NASA ASRS Text
Title: B777 flight crew on a trans-Pacific flight reported large excursions in altitude and speed during an encounter with severe turbulence in the vicinity of Kodiak; AK.
Narrative: Approaching ODK [at] FL340. Message from dispatch received saying [an air carrier flight] in front of us over ODK reported moderate turbulence at FL360 and descended to FL330 with a smooth ride. We then descended to 330. Passengers were seated and FA advised of area of reported turbulence as a precaution. West of ODK we started to encounter moderate to severe turbulence. FA told to take jump seats and ATC was advised we were unable to maintain altitude and requested block FL320-340. We received block altitude from ANC center. Alt deviation of 300+ feet and airspeed changes of 40+ knots associated with the turbulence and we suspect that some altitude deviation occurred after reporting unable to maintain altitude; but before receiving block altitude of FL320-340. Speed at cruise was about 285 but with speed changes we were as high as 330 which exceeded red line by 18 knots to 240 knots on the low end!
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.