Singapore Airlines flight dropped 54 metres in four seconds, report finds

The turbulance-hit Singapore Airlines flight dropped 54 metres in four seconds before British man Geoffrey Kitchen died and dozens of other passengers were injured, a report has found.

Preliminary findings released on Wednesday showed that a rapid change in gravitational force and a 54-metre altitude drop caused injuries amid the horror flight last week.

Mr Kitchen died of a suspected heart attack and dozens were injured after flight SQ321, flying from London to Singapore, encountered what the airline described as sudden, extreme turbulence while flying over Myanmar.

The May 21 flight on a Boeing 777-300ER plane carrying 211 passengers and 18 crew diverted to 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 Singapore Transport Ministry said in a statement.

"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," it said, citing information extracted 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 (54 m), from 37,362 ft to 37,184 ft. This sequence of events likely caused the injuries to the crew and passengers," it added.

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.

Singapore Airlines said it acknowledged the report and was cooperating fully with the investigation.

The airline late on Tuesday had said 42 people who were on board the flight were still in Bangkok, including 26 passengers receiving medical treatment in hospital.

Among those initially hospitalised were patients with spinal cord injuries and some with brain and skull injuries, according to Thai medical officials.

The investigation team comprised Singaporean investigators, and US representatives from Boeing, the National Transportation Safety Board (NTSB) and the US Federal Aviation Administration (FAA). The Singapore transport ministry said the probe was ongoing.