ASN Wikibase Occurrence # 150700
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Narrative:A Boeing 777-300, registration A6-ETC, operating a scheduled passenger flight from Manila, Philippines to Abu Dhabi (United Arab Emirates) encountered a region of severe turbulence.
|Fatalities:||Fatalities: 0 / Occupants: |
|Aircraft damage:|| Minor|
|Location:||over the Bay of Bengal -
|Phase:|| En route|
|Nature:||Passenger - Scheduled|
|Departure airport:||Manila-Ninoy Aquino International Airport (MNL/RPLL) |
|Destination airport:||Abu Dhabi International Airport (AUH/OMAA) |
|Investigating agency: ||GCAA UAE|
|Confidence Rating:|| Accident investigation report completed and information captured|
The flight was approximately 194 nautical miles south south west of Yangon, Myanmar, at FL340 over the Bay of Bengal having just passed waypoint RINDA while transiting from the boundary of the Yangon Flight Information Region [FIR] and Kolkata FIR.
The Captain had left the flight deck to take a comfort break. The F/O was the Pilot Flying [PF] and the third crewman, also an F/O, was in the supernumerary seat who was assisting the PF with the radio communication with Yangoon and Kolkata Air Traffic Control (ATC). The second F/O was sitting on the jump seat as he was not CRP qualified, assisting the PF with managing the ATC communications.
The crew stated that the enroute weather was CAVOK prior to the event. However, the crew observed on the weather radar an isolated cumulonimbus (Cb) buildup directly on the flight path, ahead of the flight at about 20nm, or approximately 2 minutes track distance to run from the point it was observed.
During the Captains absence from the flight deck, the remaining crew received confusing and contradictory information on the Yangon frequency during the hand over from the Yangon Flight Information Region [FIR] to Kolkota FIR, with a contributory CPDLC uplink delay distracting the PF and supernumerary crew member.
The crew altered track to 315°, laterally off set to the right from the airway to avoid the Cb, the flight passed the Cb and when abeam the cell approximately 7 nm laterally off set, the airplane encountered severe turbulence for approximately 45 seconds.
During the severe turbulence encounter, the autopilot disconnected, the aircraft climbed approximately 600 feet and the stick shaker activated.
Following the turbulence the autopilot was re-engaged and the crew used the Mode Control Panel [MCP] to recover to the assigned flight level.
During the turbulence encounter, several cabin crew and passengers were injured. The vertical acceleration(g) maximum loads were +1.98 and -0.68.
The Captain was not on the flight deck when the event occurred, the Captain was in the business class cabin and occupied one of the vacant business class seats and remained there for the duration of the severe turbulence encounter. Following the severe turbulence encounter the captain returned to the flight deck.
CAUSAL AND CONTRIBUTING FACTORS
The following have been identified as contributing factors.
This combination of factors contributed to the late track deviation:
- Crew coordination
- Crew Resource Management
- HF Communications difficulties
- The absence of the Captain from the flight deck during the FIR transition and subsequent radio communication problems.
- The late recognition of the adverse weather on the weather radar
- The Captains delayed return to the flight deck immediately after the severe turbulence encounter effected the normalisation of the CRM environment.
Cabin Crew [CC]:
- Not effectively monitoring the passenger use of the lavatories when the seat belt sign has been switch on.
- Performing routine CC organisational duties when the seat belt sign is on in the galley and associated areas.
| || |
|Investigating agency: ||GCAA UAE |
|Status: ||Investigation completed|
|Download report: || Final report|
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