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B747-100 PIC initiates PIC emergency authority/authorized, turns off course from R578 and descends approximately 700 mi west of lax due to severe turbulence. Actions coordination with ZOA through comrdo on HF frequency.
| Attributes | |
| ACN | 573801 |
| Time | |
| Date | 200302 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | intersection : fears |
| State Reference | FO |
| Altitude | msl single value : 35000 |
| Environment | |
| Flight Conditions | VMC |
| Weather Elements | Turbulence |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B747-100 |
| Operating Under FAR Part | Part 121 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 19000 flight time type : 1500 |
| ASRS Report | 573801 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | controller military : 20 controller radar : 29 flight time last 90 days : 80 flight time total : 11038 flight time type : 800 |
| ASRS Report | 573122 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather other anomaly other other spatial deviation |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance flight crew : regained aircraft control flight crew : took evasive action flight crew : exited adverse environment |
| Supplementary | |
| Problem Areas | Weather Environmental Factor |
| Primary Problem | Weather |
Narrative:
We were at cruise, FL350, from kona, hi, to ZZZ, ca, when we encountered moderate to severe turbulence at approximately 80 mi west of fears intersection on R578. Aircraft was shaking so badly we could not read the instruments. Airspeed was fluctuating +/-25 KTS, altitude +/-300 ft. If it had been any worse, we felt a loss of control was possible. We decided a change in altitude was imperative. We turned the aircraft 90 degrees to track to the south of R578. At 15 mi we descended to FL330 and turned east to parallel R578 at 15 mi. We contacted san francisco radio on 8843 and obtained a clearance immediately to descend to FL310. At FL310 we turned back on track and turbulence subsided gradually. The whole event lasted approximately 15 mins. WX charts did not depict or forecast severe turbulence on this route.
Original NASA ASRS Text
Title: B747-100 PIC INITIATES PIC EMER AUTH, TURNS OFF COURSE FROM R578 AND DSNDS APPROX 700 MI W OF LAX DUE TO SEVERE TURB. ACTIONS COORD WITH ZOA THROUGH COMRDO ON HF FREQ.
Narrative: WE WERE AT CRUISE, FL350, FROM KONA, HI, TO ZZZ, CA, WHEN WE ENCOUNTERED MODERATE TO SEVERE TURB AT APPROX 80 MI W OF FEARS INTXN ON R578. ACFT WAS SHAKING SO BADLY WE COULD NOT READ THE INSTS. AIRSPD WAS FLUCTUATING +/-25 KTS, ALT +/-300 FT. IF IT HAD BEEN ANY WORSE, WE FELT A LOSS OF CTL WAS POSSIBLE. WE DECIDED A CHANGE IN ALT WAS IMPERATIVE. WE TURNED THE ACFT 90 DEGS TO TRACK TO THE S OF R578. AT 15 MI WE DSNDED TO FL330 AND TURNED E TO PARALLEL R578 AT 15 MI. WE CONTACTED SAN FRANCISCO RADIO ON 8843 AND OBTAINED A CLRNC IMMEDIATELY TO DSND TO FL310. AT FL310 WE TURNED BACK ON TRACK AND TURB SUBSIDED GRADUALLY. THE WHOLE EVENT LASTED APPROX 15 MINS. WX CHARTS DID NOT DEPICT OR FORECAST SEVERE TURB ON THIS RTE.
Data retrieved from NASA's ASRS site as of July 2007 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.