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When they received reports of severe turbulence ahead at their altitude an A330 flight crew exercised emergency authority to descend without clearance when they were unable to obtain clearance in a timely manner from oceanic control.
| Attributes | |
| ACN | 1168184 |
| Time | |
| Date | 201404 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZZ.ARTCC |
| State Reference | FO |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | A330 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | First Officer Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter Weather / Turbulence |
Narrative:
A company flight 30 min ahead of us at fl 390 reported descending to lower altitude on guard frequency due to severe turbulence and advised us to do so also. We were unable to contact control in a timely manner [although we were already] entering moderate turbulence; so we [advised our intentions in the blind]; checked TCAS for traffic; turned slightly off course and descended to FL300 to avoid severe turbulence; injury; and possible damage to the aircraft. We then advised control of our descent on cpdlc and were approved to cruise at lower altitude (no SIGMET had been issued). We advised dispatch; checked fuel; and climbed back to flight plan altitude later upon coast in with control. We then continued without incident. (Note: as captain; I was in the cabin on scheduled rest break during above incident and was not in cockpit to witness above events but I would have done the same thing the relief crew did using rvsm contingency plans as far as practical to avoid severe turbulence.)
Original NASA ASRS Text
Title: When they received reports of severe turbulence ahead at their altitude an A330 flight crew exercised emergency authority to descend without clearance when they were unable to obtain clearance in a timely manner from oceanic control.
Narrative: A company flight 30 min ahead of us at FL 390 reported descending to lower altitude on Guard Frequency due to severe turbulence and advised us to do so also. We were unable to contact Control in a timely manner [although we were already] entering moderate turbulence; so we [advised our intentions in the blind]; checked TCAS for traffic; turned slightly off course and descended to FL300 to avoid severe turbulence; injury; and possible damage to the aircraft. We then advised Control of our descent on CPDLC and were approved to cruise at lower altitude (no SIGMET had been issued). We advised Dispatch; checked fuel; and climbed back to flight plan altitude later upon coast in with Control. We then continued without incident. (Note: As Captain; I was in the cabin on scheduled rest break during above incident and was not in cockpit to witness above events but I would have done the same thing the relief crew did using RVSM contingency plans as far as practical to avoid severe turbulence.)
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.