China’s flag carrier is investigating claims a flight from Hong Kong to the Chinese mainland suddenly lost air pressure and dropped 6,000 meters (19,600 ft) because the pilots were smoking in the cockpit and accidentally pushed the wrong buttons.
Air China flight CA106, en route from Hong Kong to the northeastern Chinese city of Dalian, descended from above 10,000 meters (32,800 ft) to below 4,000 meters (13,100 ft) in less than nine minutes Tuesday, according to phone GPS data shared with CNN by a passenger on board.
The Boeing 737 jetliner was carrying 153 passengers and nine crew members and landed safely in Dalian, the country’s civil aviation regulator said Thursday.
Citing unnamed industry sources, multiple Chinese state media outlets reported the cockpit crew were smoking in violation of aviation regulations, and caused the loss of cabin pressure and drop in altitude when they mistook two switches as air recycling fans and turned them off.
Upon discovering their error, the crew turned the switches back on. The plane climbed to around 7,500 meters (24,600 ft) and flew to its destination with a less-than-adequate oxygen level in the cabin, according to state media.
Air China said Wednesday the crew is being investigated by the Civil Aviation Administration of China (CAAC).
“If the investigation discovers crew behaviors that have violated rules and regulations, we will adopt a zero-tolerance attitude and seriously punish those found responsible,” the airline said in a statement.
CAAC said investigators had inspected the aircraft and questioned the crew. The regulator added that the plane’s “black boxes” — the flight data recorder and cockpit voice recorder — had been sent to its laboratory for decoding and analysis.
In a video obtained by the Beijing News, a flight attendant is seen walking down the aisle to check on passengers, some of who are putting on oxygen masks in response to a pre-recorded announcement in Chinese and English asking them to do so.
Hoby Sun, the passenger who provided CNN with the flight altitude data, said everyone was calm when the oxygen masks dropped.
“I didn’t think too much of it at the time — we didn’t know what was going on, nor did the flight attendants it seemed,” he told CNN Thursday.
“I’m not physically hurt, but the psychological impact lingers. When I close my eyes, I see the oxygen masks dangling in front of me,” Sun added.
Air China, headquartered in Beijing and a member of the Star Alliance global network, has a fleet of more than 600 planes. Last year, the airline and its subsidiaries carried 102 million passengers across six continents, according to company statistics.
Its last and only fatal accident was in 2002 when a Boeing 767 jetliner crashed into a hill in bad weather near Busan, South Korea, killing 129 of the 166 people on board.
CNN’s Nanlin Fang in Beijing contributed to this report.