Weather most likely to blame for 4.6 seconds of terror on Singapore Airlines flight SQ321, report finds

For less than 5 seconds, passengers and crew on a Singapore Airlines flight were trapped on a terrifying rollercoaster ride, a preliminary report has found.

A preliminary report on the terrifying Singapore Airlines’ in-flight drama has revealed those on-board experienced something akin to a rollercoaster ride over less than 5 seconds, leaving one person dead and scores of others injured.

The Transport Investigation Safety Bureau of Singapore pointed to weather as the most likely culprit for the sudden violent movement of the Boeing 777-300ER over Myanmar on May 21.

So strong was the updraft experienced by flight SQ321, there was nothing pilots could do as the widebody jet was forced up 362 feet in the blink of an eye,

The report noted the flight was likely flying over an area of “developing convective activity” causing fluctuations in gravitational forces recorded as vertical acceleration.

This resulted in an initial decrease in G force in the cabin from positive 1.35G to negative 1.5G in 0.6 of a second.

As a result of the change, objects and passengers and crew who were not buckled up became airborne, the report said.

Within four seconds, vertical acceleration changed again from negative 1.5G to positive 1.5G causing those who were airborne to fall to the floor.

“The rapid changes in G over the 4.6 second duration resulted in an altitude drop of 178ft, from 37,362ft to 37,184ft,” said the report.

“This sequence of events likely caused the injuries to the crew and passengers.”

In an effort to the get the flight back under control the pilots disengaged the autopilot in the midst of the rapid changes in altitude, the report said.

After manually flying the plane for 21 seconds, the autopilot was re-engaged.

It was also noted that the seatbelt sign was turned on but not until after the first upward movement.

The aftermath of a severe turbulence episode on SQ321. Picture: X

Australian and International Pilots Association safety and technical director Steve Cornell said the change in G forces over such a short space of time would have felt similar to a rollercoaster reaching its peak and then commencing a fast descent.

Captain Cornell said there had been thunderstorm activity in the area around the time of the incident so it was not surprising weather was considered the likely reason for the sudden uncommanded movement.

Almost half of the 211 passengers on board, and six of the 18 crew were injured in the episode, which resulted in the flight from London to Singapore being diverted to Bangkok.

The report noted the flight experienced no further turbulence, as it descended into Suvarnabhumi Airport, landing about an hour after the incident.

56 Australians were among the passengers, 14 of whom suffered serious injuries.

A British passenger Geoff Kitchen, 73, suffered a heart attack and died on-board shortly after the incident.

As of Wednesday, 28 people from the flight remained in hospitals in Bangkok.

Singapore Airlines released a statement in response to the preliminary report, reiterating their co-operation with the relevant authorities in the ongoing investigations.

“We are committed to supporting our passengers and crew members who were on board SQ321 on that day, as well as their families and loved ones,” said the statement.

“This includes covering their medical and hospital expenses, as well as any additional assistance they may need.”

The Singapore TISB was receiving assistance in the investigation from the US National Transportation Safety Board and Boeing.