A Singapore Airlines (SIA) flight that left Changi Airport early yesterday made a U-turn less than an hour after take-off due to a drop in cabin pressure.
It is not known what caused this to happen on the Boeing 777-300ER, but sources told The Straits Times that passengers seated at the back, near the cargo door, heard a thumping sound.
According to tracker FlightRadar24, SQ336, bound for Paris had climbed to 24,000 ft (7,315m) and was over Malaysia when it turned back towards Singapore.
Oxygen masks were deployed and the aircraft descended to 6,000 ft (1,829m).
The plane had to circle for about an hour to dump fuel before it could land; a common procedure to reduce the weight of the aircraft to ensure a safe landing.
Confirming the incident, an SIA spokesman said there were 234 passengers and 17 crew on board the aircraft.
There were no injuries reported.
At Changi Airport, emergency vehicles were standing by to receive the flight, which touched down at 2.30am.
Following an aircraft change, the flight departed Singapore at 6am and arrived in Paris just after noon (7pm Singapore time) the same day.
Flight SQ336 was originally scheduled to arrive in the French capital at 7.15am yesterday, Paris time.
A traveller who posted photos on Twitter of the inside of the plane said some passengers had been transferred to the SIA flight after an Air France service they were initially booked on was cancelled due to technical issues.
A loss of cabin pressure during flight can have serious consequences, safety experts say. At 40,000 ft (12,192m), people have as little as 18 seconds of useful consciousness if they are starved of oxygen.
In 2005, a Helios Airways plane en route from Cyprus to Athens crashed into a mountain after a loss of cabin pressure, killing all 115 passengers and six crew on board.
In January 2014, an SIA flight from London had to be diverted to Baku, Azerbaijan, after a fall in cabin pressure caused oxygen masks to be automatically deployed.
About 20 minutes after the Singapore-bound flight departed, some travellers reported a loud noise coming from one of the doors of the Airbus 380.
Investigations later revealed that the incident was caused by a small undetected crack in one of the aircraft doors, which allowed air from outside to enter the plane.
SIA had to fly an empty plane to eventually pick up the 467 passengers who were stranded in Baku.