One passenger was killed and 30 injured after a Singapore Airlines flight from London hit severe turbulence en route on Tuesday, forcing it to make an emergency landing in Bangkok, officials and the airline said.

"Singapore Airlines offers its deepest condolences to the family of the deceased. We deeply apologise for the traumatic experience that our passengers and crew members suffered on this flight," the airline said, adding it was working with Thai authorities to provide all necessary assistance.

The flight fell into an air pocket while cabin crew was serving breakfast before it encountered turbulence, prompting the pilots to request an emergency landing, Suvarnabhumi airport general manager Kittipong Kittikachorn told a press conference.

A 73-year-old British man died during the incident, likely due to a heart attack, he said. Seven people were critically injured with head injuries.

Eighteen people have been hospitalised and 12 are being treated in hospitals, Singapore Airlines said.

It was not immediately possible to reconstruct the incident from publicly available tracking data, but a spokesperson for FlightRadar 24 said it was analysing data at around 07:49 GMT which shows the plane tilting upwards and return to its cruising altitude over the space of a minute.

A passenger who was on the flight told Reuters that the incident involved the sensation of rising then falling.

"Suddenly the aircraft starts tilting up and there was shaking so I started bracing for what was happening, and very suddenly there was a very dramatic drop so everyone seated and not wearing a seatbelt was launched immediately into the ceiling," Dzafran Azmir, a 28-year-old student on board the flight told Reuters.

"Some people hit their heads on the baggage cabins overhead and dented it, they hit the places where lights and masks are and broke straight through it," he said.

Kittikachorn said most of the passengers he had spoken to had been wearing their seatbelts.

The spokesperson for FlightRadar 24 said with regard to data showing a drop in height, "our initial thinking is the turbulence event is prior to the standard descent from 37,000 to 31,000 feet. That appears to just be a flight level change in preparation for landing."

The Boeing 777-300ER plane with 211 passengers and 18 crew was headed to Singapore when it made the emergency landing, the airline said.

Singapore news outlet CNA carried blurry pictures supplied by readers that it said appeared to be from the flight. They showed anxious passengers clinging to seats, with oxygen masks hanging from above, personal items strewn across the aisle and rubbish spilled on the floor of the cabin crew area.

Suvarnabhumi airport said the plane requested an emergency landing at 3:35pm local time and landed at 3:51. Uninjured passengers disembarked and an another aircraft will fly them onwards. The airline said it landed at 3:45.

TURBULENCE

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 U.S. 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.

Singapore Airlines, which is widely recognized as one of world's leading airlines and is a benchmark for much of the industry, has not had any major incidents in recent years.

Its last accident resulting in casualties was a flight from Singapore to Los Angeles via Taipei, where it crashed on Oct. 31, 2000 into construction equipment on the Taiwan Taoyuan International Airport after attempting to take off from the wrong runway. The crash killed 83 of the 179 people on board.

Singapore Airlines has had seven accidents according to records by the Aviation Safety Network.

Boeing (BA.N), opens new tab said it was in touch with Singapore Airlines and was ready to provide support. It referred further questions to the airline and local authorities.

"We extend our deepest condolences to the family who lost a loved one, and our thoughts are with the passengers and crew," it said.