The Airbus A380 registered VH-OQI was flying at 31,000ft when it made rapid descent to 9,800ft at -6,000ft per minute.
From a Qantas spokesperson
“The captain of yesterday’s QF1 from Sydney to Dubai decided to return to Sydney about an hour into the flight after a cockpit indicator light reported a fault with part of the system that helps regulate the cabin temperature.”
“This system carries hot air from the engines which is used to help heat the cabin.”
“Because the flight was only an hour out of Sydney, it was more practical to return to Sydney where we do a lot of our A380 maintenance to have the fault inspected.”
“Customers were accommodated in hotels overnight whilst engineers inspected the aircraft and fixed the fault.”
“The QF1 service departed Sydney earlier this morning.”