Flight History
On 1 August 2017, a Boeing 777-200 aircraft, registration 9V-SQN, departed Singapore Changi Airport at approximately 1305 hours local time for Bangkok, Thailand, as a scheduled passenger flight. The flight crew consisted of a Captain, a First Officer (FO), and a Second Officer (SO). The SO, under training, occupied the right seat as pilot flying (PF), while the Captain, serving as instructor, was in the left seat as pilot monitoring (PM). The FO acted as Safety Officer in the observer seat.
After takeoff, the fasten seatbelt sign, set to AUTO, turned off automatically at 10,300 feet. The PM noted good visibility and observed thick clouds building on the left side of the flight path and isolated clouds on the right. The weather radar indicated extensive cumulonimbus (CB) clouds on the left and scattered CBs on the right. The PF initially planned to deviate left but, after discussing with the PM, decided to deviate right to pass through clear areas. With ATC clearance, the aircraft climbed to 20,000 feet and later to 28,000 feet. The PM requested a heading of 010 degrees, but ATC initially cleared only 360 degrees due to traffic, later approving 010 degrees.
At 1317 hours, while the PM was making a passenger announcement about possible turbulence, the aircraft encountered moderate to severe turbulence lasting three to five seconds. The fasten seatbelt sign had been switched on 28 seconds before the turbulence, according to flight data. After the turbulence ceased, the sign was turned off. The Captain then went to the cabin to assess injuries.
Injuries
Six persons sustained injuries: one male passenger suffered a serious injury (fractured right foot) while walking back from the lavatory; two female cabin crew members sustained serious injuries (hairline fractures in heels); three female cabin crew members had minor injuries. All injured received medical attention upon arrival in Bangkok.
Personnel Information
The Captain, aged 46, held a valid license and medical certificate, with 6900 total flying hours. The First Officer had relevant qualifications. The Second Officer was undergoing line training.
Aircraft Information
The aircraft was a Boeing 777-200, registration 9V-SQN, powered by two Rolls-Royce Trent 800 engines. It was operated by Singapore Airlines. No damage to the aircraft was reported.
Flight Recorder Data
Flight Data Recorder (FDR) and Quick Access Recorder (QAR) data confirmed the turbulence encounter at 1317 hours. The fasten seatbelt sign was activated 28 seconds before the onset of turbulence.
Conclusion
The investigation found that the aircraft was operating in an area with thunderstorms and CB clouds. The fasten seatbelt sign was switched on before the turbulence, but the flight crew had insufficient time to complete a safety announcement to warn the cabin crew. The cabin crew were performing meal service and not seated at the time. The aircraft sustained no damage.