Air China is investigating two pilots on claims that they were smoking in the cockpit and pushing the wrong buttons, causing a passenger plane from Hong Kong to Dalian to rapidly descend mid-flight, South China Morning Post reports.
Flight CA106 dropped 7,620 meters (25,000 feet) in 10 minutes on the evening of July 10 around 30 minutes after it departed from Hong Kong International Airport. The 159-seat Boeing 737 lost altitude as it flew over Shantou and Xiamen in southern China, causing oxygen masks to be released in the cabin.
Some passengers shared photos and videos on social media of the emergency descent. Despite the mayday moment, the overall mood in the cabin appeared to be relatively calm, with one passenger giving the thumbs up in his oxygen mask selfie.
“The announcement from the cockpit said the ability to increase oxygen in the cabin malfunctioned so the plane lost pressure," wrote one of the passengers on Weibo.
Flight tracking data showed the aircraft leveling off after dropping to an altitude of 10,000 feet before climbing back up again to cruising altitude without making an emergency landing. The flight evenutally landed safely in Dalian later that evening without incident three hours after departure. No injuries or damages were reported.
State media later revealed that two unnamed pilots may have been smoking in the cockpit, thus violating aviation regulations, though exact details of how exactly the event unfolded are still a little unclear. The Paper reports that crew members may have mistaken two switches for ventilation fans and turned them off, leading to cabin decrompression. The pilots then descended to 10,000 feet, as is standard practice when an aircraft is undergoing depressurization.
Reports indicate that the pilots may have also mishandled the plane's re-ascent. According to The Paper, the aircraft hiked up to an altitude of 7,500 meters (24,000 feet) and continued on towards its final destination, despite the fact that oxygen levels were less than adequate for passengers in the cabin.
Industry experts told Reuters the decision to continue to Dalian was unusual given that the oxygen masks had been deployed. According to experts, there could have been risk of another decompression event after the oxygen masks were all used up. The masks are one-time use and only provide enough air to last 12 to 20 minutes.
Passengers also told Sina that they experienced another scare as they approached Dalian, when an announcement was made to put the masks back on after they had already run out of oxygen. However crew members reassured passengers that it was just a false alarm.
Air China addressed the crew misconduct allegations in a statement posted to Weibo. "If the investigation reveals that the crew has violated regulations, the company will seriously deal with the responsible person with zero tolerance," the airline's statement read.
The aircraft's flight data recorder and cockpit voice recorder have been submitted to the Civil Aviation Administration of China (CAAC) for further review. The CAAC also inspected the aircraft and questioned crew members. Air China confirmed that the two pilots are currently under investigation by the CAAC.
[Images via Weibo]