A Qantas airliner carrying 99 passengers from Adelaide to Melbourne was forced rapidly to descend 26,000 feet after a sudden cabin depressurisation this morning.
According to media reports, oxygen masks dropped from the overhead consoles on the Boeing 737-400 as the pilots of flight QF670 announced that they would have to make a rapid descent from a cruising altitude of 36,000 feet to just 10,000 feet.
The incident occurred 30 minutes from Melbourne and the pilots obtained air traffic control permission to fly at the lower altitude for the rest of the flight into Melbourne.
The 21-year-old plane, registration VH-TJH, left Adelaide at 6.13 am and had just crossed into Victoria when the cabin lost pressure.
"It experienced a depressurisation in the cabin," Qantas spokeswoman Sophia Connelly said adding, "We think it was related to the airconditioning at this stage; we're waiting on confirmation of that".
The masks in the cabin dropped automatically as a result of the depressurisation, she said, but it was thought the passengers did not need to put them on immediately.
"It was automatic, rather than a deployed [mask] drop," she said.
"Flight crew would have got an indication in the cockpit and then requested a rapid descent to 10,000 feet into Melbourne. The captain made an announcement to say that we were making a controlled rapid descent".
The aircraft landed at Melbourne at 7.53 am.
"The aircraft landed without incident and there was no safety issue at any time. All passengers were fine, no one needed medical assistance. Our duty manager met the aircraft on arrival and they [the passengers] were all all right," Connelly said.
"Emergency services were not required to meet the aircraft and engineers are currently assessing the aircraft," she said.
A passenger Peter Cowan was quoted as saying that he had just finished his meal when "all of a sudden the plane started to drop and then the oxygen masks were deployed".
"I fly a lot around Australia and overseas and everything else like that, and it's the first time I've been on a plane where the oxygen masks were deployed, so that's a fairly scary experience, actually," he added.
Cowan said passengers were advised to put on their masks while the plane descended, but they were not told the reason for their descent for several minutes.
A number of passengers began to panic, Cowan said.
"One in particular was fairly panicked and there was a couple of hostesses trying to fan her down," he said.