A 73-year-old British man died and more than 30 others were injured when a Singapore Airlines flight from London to Singapore was hit by severe turbulence near Thailand on Tuesday.
The Boeing 777-300ER aircraft was diverted to Bangkok, where it made an emergency landing at 15:45 local time.
Passengers said the aircraft suddenly dropped - and people and objects were thrown around the cabin.
The flight was carrying 211 passengers and 18 crew, Singapore Airlines said. It offered its deepest condolences to the family of the deceased.
Authorities in Bangkok say the man probably died of a heart attack. His wife has been admitted to hospital, but her condition is unknown.
A passenger told BBC that the flight had completed 10 hours and there was no sign to put the seat belts on. All of a sudden there was turbulence.
Another passenger told Reuters that the aircraft suddenly started tilting up and later there was a dramatic drop.
Those not wearing a seatbelt hit the ceiling. Some hit their heads on the baggage cabins overhead, he added.
The airline said 31 people have been taken to hospital, while the rest of the passengers and crew were provided treatment at Suvarnabhumi International Airport in Bangkok.
Meanwhile, Boeing has said it is in contact with Singapore Airlines and is offering support.
Singapore's Transport Minister Chee Hong Tat said the government would provide assistance to the passengers and their families.
It is still not clear how events unfolded. Experts claim turbulence is most commonly caused by aircraft flying through clouds, but there is also "clear air" turbulence which is not visible on the plane's weather radar.
Kulsuma Aktergetty images