A Jetstar Asia Airbus A320-200, registration 9V-JSR performing flight 3K535 from Singapore (Singapore) to Phuket (Thailand), was climbing through FL240 out of Singapore when the crew initiated a rapid descent to FL100 and returned to Singapore for a safe landing about 50 minutes after departure.

The airline reported a ventilation issue prompted the precautionary return to Singapore.

A replacement Airbus A320-200 registration 9V-JSI reached Phuket with a delay of 3 hours.