A Vietnam Airlines co-pilot was found dead in his hotel room in the French capital Paris December 5, and he is suspected to have had a stroke.
Nghiem Dinh Tuan, 52, was staying there with other crew members of his Boeing 777 aircraft, and was supposed to have flown back to Vietnam the next day.
The cause of death has not been officially determined yet, but online newspaper VnExpress quoted a source as saying Tuan died of a stroke.
The others said they had not noticed him behaving unusually the day before his death. He had played some sport in the afternoon before returning to his room saying he was tired.
When they failed to see him the following morning, they went to his room and found him dead.
A Vietnam Airlines representative said Tuan was a quiet man who did not drink or smoke.
The ex-army pilot was set to retire soon, according to the airline.
His sudden death did not affect the scheduled flight since there are always back-up pilots available for long-haul flights, it added.
The Paris police are investigating Tuan's death, but his body was brought back to Vietnam on Thursday (December 8).