SINGAPORE - Preliminary findings of an investigation into the Singapore Airlines flight hit by severe turbulence last week showed a rapid change in gravitational force and a 54-metre altitude drop caused injuries, Singapore’s transport ministry said on Wednesday.
One passenger died of a suspected heart attack and dozens were injured after Singapore Airline Flight SQ321, flying from London to Singapore, encountered what the airline described as “sudden, extreme turbulence” while flying over Myanmar. The ministry said the investigation was ongoing.
Flight SQ321 from London to Singapore, on a Boeing 777-300ER carrying 211 passengers and 18 crew, diverted to Suvarnabhumi Airport in Bangkok for an emergency landing after the plane was buffeted by turbulence that flung passengers and crew around the cabin, slamming some into the ceiling.
“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 ministry said in a statement, citing a report by the Transport Safety Investigation Bureau of Singapore.
“The vertical acceleration changed from negative 1.5G to positive 1.5G within 4 seconds. This likely resulted in the occupants who were airborne to fall back down.
“The rapid changes in G over the 4.6 seconds duration resulted in an altitude drop of 178 feet (54 metres), from 37,362 to 37,184 feet. This sequence of events likely caused the injuries to the crew and passengers,” it said.
Shaken passengers described scenes of chaos in the minutes after the incident, with the turbulence throwing people upwards then into the aisle, many left with bleeding and head wounds.
Photographs of the cabin showed gashes in the overhead cabin panels, oxygen masks and panels hanging from the ceiling and luggage strewn around. A passenger said some people’s heads had slammed into lights above the seats and broken the panels.
The preliminary report said that upon the flight encountering slight vibrations there was an “uncommanded increase in altitude, resulting in the autopilot pitching the aircraft downwards”. The pilots experienced an increase in airspeed and responded by applying speed brakes.
“While managing the airspeed … it was heard that a pilot called out that the ‘fasten seat belt’ sign had been switched on,” it said.
The investigation team comprised Singaporean investigators, representatives from Boeing and United States officials from the National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA). The Singapore transport ministry said the investigation was ongoing.
Forty-five people who were on board the flight were still in Bangkok as of Tuesday, the airline said, including 28 passengers receiving medical treatment in hospital.
Officials of Samitivej Srinakarin Hospital have said that most of the injuries involved the head or spine, and more than a dozen people needed surgery.
Singapore Airlines has since introduced tighter cabin restrictions during turbulence, though stopped short of compelling passengers to wear seatbelts for the whole flight.
While injuries or deaths from such events are rare, a Qatar Airways flight over Turkey on Sunday also encountered extreme turbulence before the plane landed as scheduled in Dublin. Twelve people on board were hurt.