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B777 on north atlantic track system utilizing mach technique separation criteria reduced speed due to turbulence. Advised gander control when reducing and when resuming assigned mach.
| Attributes | |
| ACN | 597767 |
| Time | |
| Date | 200310 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : czqx.artcc |
| State Reference | NF |
| Altitude | msl single value : 38000 |
| Environment | |
| Weather Elements | Turbulence |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : czqx.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B777 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Route In Use | enroute : atlantic |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 597767 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument pilot : multi engine |
| ASRS Report | 597762 |
| Events | |
| Anomaly | inflight encounter : turbulence non adherence : clearance other anomaly |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance controller : issued advisory flight crew : took precautionary avoidance action flight crew : exited adverse environment |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | ATC Human Performance Environmental Factor Flight Crew Human Performance |
| Primary Problem | Environmental Factor |
Narrative:
Approaching 47N, 030W, we encountered moderate turbulence and were forced to reduce speed from mach .84 assigned to mach .82 for safety reasons. The time of the speed reduction was XA30Z. Gander was notified immediately upon reduction of speed. We resumed speed about 40 mi west of 030W on track. Gander was notified and a request for the speed reduction was initiated. I had exercised my emergency authority/authorized for safety of aircraft, crew and passenger. Speed was resumed prior to any permission by gander to reduce speed. Gander was notified of our resumption of normal speed as soon as it occurred. The segments involved were 4820N to 4730N to 4640N. The estimate for 4640N was not impacted by the speed change. Dispatch was notified about the speed change and the area of turbulence.
Original NASA ASRS Text
Title: B777 ON NORTH ATLANTIC TRACK SYS UTILIZING MACH TECHNIQUE SEPARATION CRITERIA REDUCED SPD DUE TO TURB. ADVISED GANDER CTL WHEN REDUCING AND WHEN RESUMING ASSIGNED MACH.
Narrative: APCHING 47N, 030W, WE ENCOUNTERED MODERATE TURB AND WERE FORCED TO REDUCE SPD FROM MACH .84 ASSIGNED TO MACH .82 FOR SAFETY REASONS. THE TIME OF THE SPD REDUCTION WAS XA30Z. GANDER WAS NOTIFIED IMMEDIATELY UPON REDUCTION OF SPD. WE RESUMED SPD ABOUT 40 MI W OF 030W ON TRACK. GANDER WAS NOTIFIED AND A REQUEST FOR THE SPD REDUCTION WAS INITIATED. I HAD EXERCISED MY EMER AUTH FOR SAFETY OF ACFT, CREW AND PAX. SPD WAS RESUMED PRIOR TO ANY PERMISSION BY GANDER TO REDUCE SPD. GANDER WAS NOTIFIED OF OUR RESUMPTION OF NORMAL SPD AS SOON AS IT OCCURRED. THE SEGMENTS INVOLVED WERE 4820N TO 4730N TO 4640N. THE ESTIMATE FOR 4640N WAS NOT IMPACTED BY THE SPD CHANGE. DISPATCH WAS NOTIFIED ABOUT THE SPD CHANGE AND THE AREA OF TURB.
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.