The plane took off from London Heathrow Airport at 10.38pm local time on Monday, and was diverted to the Bangkok airport where it landed at about 3.45pm on Tuesday.

Singapore’s Transport Ministry is opening an investigation into the incident and said it would send investigators to Bangkok.

Here, the Post breaks down what air turbulence is and what passengers should do to stay safe.

1. What is air turbulence?

According to the Hong Kong Observatory, turbulence is caused by the rapid irregular motion of air, caused by storms, jet streams or when wind blows across mountain ranges.

“Turbulence usually occurs in areas where air masses with different speed, direction or temperature meet each other,” said the forecaster.

“In severe cases, the aircraft might go momentarily out of control.”

2. When does turbulence occur?

Paul Weatherilt, a pilot with Hong Kong’s flag carrier Cathay Pacific, said aircraft usually experience two kinds of turbulence.

One is the kind associated with weather, such as during thunderstorms, which are visible on the weather radar or even to the naked eye when looking out of the aircraft.

He added that aviation technology has developed to forecast such turbulence accurately and even indicated if it was predicted to be mild or severe, and pilots would stay clear of the area.

“We would be warned and bring the seat belt sign to alert the passengers,” he said.

Clear air turbulence, caused by strong wind shear and instability near jet streams, is less predictable.

“The other kind of turbulence is associated with jet streams, also known as clear air turbulence, which can be quite severe and unexpected,” he said.

Weatherilt warned that in cases of clear air turbulence, mild turbulence could escalate into severe shaking in a matter of seconds.

He pointed to the Pacific Ocean, which is one of the places with unexpected clear air turbulence caused by jet streams, while turbulence associated with poor weather could happen anywhere in the world.

3. How frequently does air turbulence cause serious injuries or fatalities?

Turbulence-related airline accidents are the most common type, according to a 2021 study by the National Transportation Safety Board.

From 2009 through 2018, the United States agency found that turbulence accounted for more than a third of reported airline accidents and most resulted in one or more serious injuries, but no aircraft damage.

The injuries reportedly included lacerations, broken bones, head wounds and loss of consciousness, mainly due to passengers not wearing their seat belts.

On April 30, a Cathay Pacific aircraft from Shanghai which tried to land in Hong Kong during an amber rainstorm battled intense turbulence and failed twice to land at the airport.

Passengers described vomiting and screaming in fear amid the bumpy and shaky ride.

The aircraft was eventually diverted to Shenzhen airport to refuel, before safely landing in Hong Kong at 2.42am the next day.

In July 2023, seven people were injured on a Hawaiian Airlines flight to Sydney, Australia, when the plane encountered severe turbulence.

In March 2023, a former White House official died after severe turbulence hit the private jet she was travelling on.

In December 2022, 20 people were sent to hospital after turbulence on a Hawaiian Airlines flight from Phoenix to Honolulu.

Weatherilt said severe accidents caused by air turbulence only happened about once a year globally and were usually associated with clear air turbulence where pilots were unable to avoid being close to jet streams.

However, experts from Reading University in the United Kingdom have warned that severe turbulence would occur more frequently as jet streams become more unpredictable due to climate change.

4. What can passengers do to keep themselves safe?

Weatherilt recommended that passengers always wear their seat belts, even when the sign is off.

“Never sit down with your seat belt undone,” he said. “People who get injured in incidents where there is unexpected turbulence, although very rare, are not sitting down with their seat belts on.”

He added that during severe turbulence, aircrew have a higher chance of being injured as passengers will mostly be seated with seat belts fastened, but crew members may be standing when the turbulence becomes worse than anticipated.

“Always have [your belt] done up because there is the possibility of an accident,” he said. “Even if you have that seat belt done up a little loosely, it will prevent you from being seriously injured.”