BANGKOK (AP) — Aviation investigators arrived in Bangkok Wednesday to learn how and why severe turbulence sent a Singapore Airlines plane into a sudden dive that tossed passengers and crew around the cabin, leaving a British man dead and dozens others injured.

Twenty people remained in intensive care in hospital after Flight SQ321, which was flying from London’s Heathrow airport to Singapore, hit the turbulence Tuesday over the Andaman Sea. The Boeing 777, which carried 211 passengers and 18 crew members, descended 6,000 feet (around 1,800 meters) in about three minutes, the carrier said.

After regaining control, the captain diverted the plane to Bangkok’s Suvarnabhumi Airport, where medical teams evaluated those aboard and sent more than 80 to hospital. Singapore Airlines said 131 passengers and 12 crew members who were well enough to travel were picked up on a special flight and arrived early Wednesday at Singapore’s Changi Airport.

Six crew members and 79 passengers stayed in Bangkok, where the majority remained in hospital, said Singapore Airlines CEO Goh Choon Phong.

<bsp-audio-player class=«HTML5AudioPlayerB» data-hours-abbreviation=«hr» data-minutes-abbreviation=«min»> </bsp-audio-player>

AP AUDIO: Aviation experts to begin probe of Singapore Airlines turbulence incident that left British man dead

In an AP interview, travel and tourism expert Anita Mendiratta says it is clear this was a weather-related incident that was going to affect any airline going through it.

Samitivej Srinakarin Hospital, where most of the injured were taken, said 20 people were being treated in intensive care while 27 others have been discharged. The ICU patients include six Britons, six Malaysians, three Australians, two Singaporeans and