The Singapore Airlines flight that was hit severe turbulence experienced a rapid change in gravitational force, plunging 178ft in altitude in just four seconds, a report has found.
It comes after a 73-year-old British man died after the incident on 21 May from a suspected heart attack.
Dozens more were injured on the London to Singapore flight with passengers describing fellow fliers being “launched into the ceiling” and overhead lockers.
Twenty-eight people are still in Thai hospitals after the plane made an emergency landing.
The Transport Safety Investigation Bureau said: “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.”
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“The rapid changes in G over the 4.6 seconds duration resulted in an altitude drop of 178ft (54m), from 37,362 ft to 37,184ft,” it added.
“This sequence of events likely caused the injuries to the crew and passengers.”
Last week, Singapore Airlines said a medical emergency was declared by the pilot, who landed in Bangkok after “sudden extreme turbulence over the Irrawaddy Basin at 37,000ft about 10 hours after departure”.
The British man who died was later named as Geoff Kitchen from Thornbury, Gloucestershire. The grandfather was with his wife Linda, who was taken to receive medical care in Bangkok.
Josh Silverstone, a broker from South London, described frantically texting his mother when the plane dropped.
He said: “I woke up on the floor. I didn’t realise what happened I must have hit my head somewhere.
“I thought I was going to die. I bought some airplane WIFI, and texted my mum, trying not to scare her, and just saying I love you. It was pretty scary.”
Over 100 passengers were taken to Bangkok’s Samitivej Hospital for treatment. Silverstone, 24, has since been discharged from hospital with minor injuries.
Hong Kong’s Greater Bay Airlines announced today that from Thursday it will ask passengers to fasten their seatbelts at all times during flights, even when the seat belt sign is off.
However, the firm said it is not a mandatory requirement, but is being advised for passenger safety.
Singapore Airlines acknowledged the report and said it was cooperating with investigators, supporting affected passengers and crew, including those with medical and hospital expenses.