China’s civil aviation regulator began investigating an Air China flight that made an emergency descent while flying from Hong Kong to the northeast city of Dalian.
Flight CA106 received a flying height alert when the aircraft was midair on Tuesday night. The crew released oxygen masks and made a rapid descent, the Northeast Regional Administration with the Civil Aviation Administration of China said.
The aircraft landed safely at Dalian airport at 10:31pm and all 153 passengers and nine crew members were safe, the administration added.
Investigators have inspected the aircraft, interviewed crew members and sent the flight data recorder and voice recorder to the China Academy of Civil Aviation Science and Technology for further analysis.
An industry insider claimed on the Internet on Wednesday that the incident was caused by crew members who were smoking in the air. The insider claimed on Weibo that crew members mistakenly depressurized the cabin when they were attempting to turn off the circulating fan in order to smoke.
The online claim has yet to be confirmed by Air China, but the nation’s flagship carrier said in a statement that the company will take a no-tolerance approach if any violation is found among crew. “Any violators will be severely punished,” the airline promised.
A passenger surnamed Sun said he realized the aircraft descended from a height of 11 kilometers to 4 kilometers by monitoring the GPS system on his mobile phone. He told Beijing News that he could not breathe properly.
The incident is still under investigation.