A passenger who has been in intensive care since the turbulent Singapore Airlines flight has been given the devastating news that her husband, Geoff Kitchen, 73, has died.

Linda Kitchen, a grandmother from the UK, suffered spinal injuries from the frightening mid-air ordeal and is receiving care in hospital in Bangkok, The Sun reports.

She was told on Wednesday morning (British time) that her husband of 51 years had died from a suspected heart attack during the terrifying incident.

The British couple had just embarked on the trip of a lifetime, taking in Japan, Indonesia and Australia over six weeks.

“The tragic news was broken to her this morning. They were such a devoted couple, you can’t imagine what it must be like for her,” a family member told The Sun.

Twenty people are still fighting for their lives in intensive care in a Bangkok hospital — three of them are Australian.

Bangkok’s Samitivej Hospital said nine had undergone surgery, while five more were awaiting surgery.

Australian officials have been helping 12 citizens and one permanent resident hospitalised in Bangkok.

Some of the 56 Australian passengers who were on board began returning to Sydney Airport on Wednesday night.

The London-Singapore flight on a Boeing 777-300ER plane diverted to Bangkok for an emergency landing on Tuesday after the plane was buffeted by turbulence that flung passengers and crew around the cabin, slamming some into the ceiling.

Josh Silverstone, 24 from south London, woke up on the floor of the plane.

“I didn’t realise what happened. I must have got hit in the head somewhere. Lots of people hit their head. Everyone was bleeding,” he told Reuters as he left the hospital on Wednesday night after being treated. He had a cut on his eye.

Silverstone had been heading to Singapore for a holiday before meeting friends in Bali. He said he still hoped to make it to the Indonesian island.

Many passengers in the hospital still being treated had spinal injuries.

“I am lucky to be able to walk,” he said.

Photographs of the interior of the plane showed gashes in the overhead cabin panels, oxygen masks and panels hanging from the ceiling and luggage strewn around. A passenger said some people’s heads had slammed into the lights above the seats and broken the panels.

“I saw people from across the aisle going completely horizontal, hitting the ceiling and landing back down in like really awkward positions. People, like, getting massive gashes in the head, concussions,” Dzafran Azmir, a 28-year-old student onboard the flight, told Reuters after arriving in Singapore.

Geoff Kitchen died and his wife Linda remains in ICU. Photo: Supplied

Singapore Airlines flew 131 passengers and 12 crew on the relief flight from Bangkok, which reached Singapore just before 5am.

There were 211 passengers including many Australians, British and Singaporeans, and 18 crew on the original flight. Injured fliers and their families remained in Bangkok.

“On behalf of Singapore Airlines, I would like to express my deepest condolences to the family and loved ones of the deceased,” Singapore Airlines CEO Goh Choon Phong said in a video message.

Officers from Singapore’s Transport Safety Investigation Bureau arrived in Bangkok on Tuesday night, Singapore’s Transport Minister Chee Hong Tat said.

As the incident involves a US company, Boeing, which makes the 777-300ER aircraft, the US National Transportation Safety Board was sending a representative and four technical advisers to support the investigation, he said.

The plane encountered sudden extreme turbulence, Goh said, and the pilot then declared a medical emergency and diverted to Bangkok.

Weather forecasting service AccuWeather said on Tuesday that rapidly developing, explosive thunderstorms near the flight path of Flight 321 most likely contributed to violent turbulence.

Turbulence-related airline accidents are the most common type of accident, according to a 2021 NTSB study.

Singapore Airlines shares were not trading on Wednesday because of a public holiday in Singapore.

-with AAP