A Singapore Airlines flight that was hit by severe turbulence last week dropped nearly 200 feet in five seconds when it experienced a rapid change in gravitational force, a preliminary investigation has found.
Flight SQ321 from London to Singapore was forced to make an emergency landing after the plane encountered what the airline described as sudden, extreme turbulence while flying over Myanmar’s Irrawaddy Basin at 37,000ft, about 10 hours after departure.
The pilot declared a medical emergency and landed the plane, carrying 211 passengers and 18 crew, at Bangkok’s Suvarnabhumi airport last Tuesday.
A 73-year-old British man, Geoffrey Kitchen, died of a suspected heart attack and dozens were injured when they were slammed into the ceiling of the plane, during what the findings suggest was a plunge of 178ft in only five seconds.
Singapore’s Transport Safety Investigation Bureau, part of the country’s transport ministry, said in a statement: “The aircraft experienced a rapid change in G [gravitational force] … This likely resulted in the occupants who were not belted up to become airborne.
“The vertical acceleration changed from negative 1.5G to positive 1.5G within four seconds. This likely resulted in the occupants who were airborne to fall back down.” The bureau cited information from the flight data and cockpit voice recorders.
“The rapid changes in G over the 4.6 seconds duration resulted in an altitude drop of 178 ft (54m), from 37,362 ft to 37,184 ft. This sequence of events likely caused the injuries to the crew and passengers.”
The preliminary report said that when the flight encountered slight vibrations, there was an uncommanded increase in altitude, causing the autopilot to pitch the aircraft downwards. The pilots experienced an increase in airspeed and responded by applying brakes.
“While managing the airspeed … it was heard that a pilot called out that the fasten seatbelt sign had been switched on,” the report said.
Singapore Airlines said on Wednesday that it was “fully co-operating with the relevant authorities in the ongoing investigations into this incident. The safety and wellbeing of our passengers and staff are our top priorities.”
It reiterated that it would cover the medical and hospital expenses of passengers and crew who were on board, as well “as any additional assistance they may need”.
According to the airline, 28 passengers are still in hospitals in Thailand, some with brain, skull and spinal cord injuries.
It announced that it would change its rules around seatbelts and onboard meals as a result of the incident.
“In addition to the suspension of hot beverage service when the seat belt sign is on, the meal service will also be suspended. Crew members will also return to their seats and secure their seatbelts when the seatbelt sign is on,” Singapore Airlines said.