Thailand and Malaysia are experiencing the first recorded death of a passenger on an international flight since January 8, 2017.
The airline was forced to cancel all scheduled flights for a week after the death of passenger Lee Cheuk, 37, from the Malaysian city of Kota Bharu, who had suffered a heart attack.
Mr Cheuk was travelling on the Kuala Lumpur-Singapore route on March 8, 2016 when he lost consciousness in the cabin, and his body was found the next day.
The Thai National Transport Safety Board (NTSB) confirmed the death on Friday.
The NTSB said it would investigate the circumstances of the death.
“The NTSB will carry out an independent investigation into the circumstances surrounding Mr Cheung’s death and will submit its report to the Malaysian government within 30 days,” the NTSB’s investigation chief, H.E. Tanakorn, said in a statement.
A video released on the NTSBs website shows Mr Cheuuk’s body on a stretcher, and a female passenger on the tarmac.
He had suffered an “accidental death”, it said.
On March 6, 2016, Mr Cheucuk boarded a flight from Kuala Lumpur to Singapore on the Royal Brunei Air Lines (RBI) flight.
He was on his way to visit his sister, who is a Malaysian citizen.
It is not clear why Mr Cheuchuk died.
His family and friends described him as a gentle, kind man, who was travelling with his sister and his parents, who are also Malaysians.
Mr Cheuk had been on his second trip to Singapore since 2014 and had recently bought a new car.
He had recently finished his PhD in mathematics and had just completed his third year of work in the field.
Read more about Singapore