History of the Flight
On 26 February 2015, Thai Airways International Public Company Limited flight TG641, operated by an Airbus A340-600 with registration HS-TNF, was flying from Narita International Airport (RJAA), Japan, to Suvarnabhumi Airport (VTBS), Thailand. The flight carried 24 crew members and 227 passengers, totaling 251 persons. Throughout the route, the aircraft experienced light clear air turbulence and was unable to maintain stable altitude at FL360 and FL380. The pilot requested and received permission from air traffic control to descend to FL340 for passenger comfort and safety, encountering occasional light turbulence and vibration.
During the descent to Suvarnabhumi, the sky was covered with clouds and occasional turbulent winds. When the aircraft descended past FL200, the pilot turned on the seat belt sign and made an announcement. Flight attendants then proceeded to check the cabin for abnormalities. The pilot-in-command operated the aircraft through cloud formation; the weather radar screen did not detect any turbulent weather conditions in the cloud.
At approximately 02:22 p.m. local time, while the aircraft was at an altitude of about FL150, at a bearing of 048 degrees and 109 nautical miles from Suvarnabhumi Airport, the aircraft suddenly bounced up and down. Flight attendants and passengers who had not fastened their seat belts were thrown upward and collided with the cabin ceiling.
Injuries and Damage
One flight attendant suffered a serious injury (a broken right arm). Four other flight attendants received minor injuries, and three passengers sustained minor injuries. The aircraft's cabin sustained damage: the oxygen mask container over the attendant seat at the rear galley cracked; the ceiling above passenger seat 56D cracked; and the ceiling light cover above the rear galley cracked. No other damage was reported.
Meteorological Information
Meteorological reports from Suvarnabhumi Airport at the time of the incident indicated winds from 180 degrees at 8 knots, visibility 10 kilometers or more, few clouds at 2,000 to 3,000 feet, and scattered clouds at 30,000 feet. Temperature was 33°C, dew point around 19-20°C, and atmospheric pressure 1009 millibars. No significant changes were forecast.
Flight Crew Information
The pilot, aged 56, held an Airline Transport Pilot License with type ratings for A330-300 and A340-500/600, and had a total flight time of 25,702 hours, including 5,168 hours on the A340-600. The co-pilot, aged 32, also held an Airline Transport Pilot License with co-pilot ratings for A330-300 and A340-500/600, and had 2,880 hours total flight time, with 1,194 hours on type. Both pilots had recent proficiency checks and were medically fit with corrective lenses requirements.
Aircraft Information
The aircraft was an Airbus A340-600, serial number 953, manufactured in 2008 by Airbus Industrie. It was owned and operated by Thai Airways International Public Company Limited, with a valid certificate of airworthiness. The four engines were Rolls-Royce Trent 556-61.
Post-Accident Actions
Following the incident, the Inflight Manager reported the number of injured persons and initial damage to the pilot-in-command. The pilot contacted the Suvarnabhumi control tower to request an ambulance and a doctor. After the aircraft parked at the gate at 02:48 p.m., the injured were transported to Samitivej Srinakarin Hospital.