An Air China jet made a rapid emergency descent after a co-pilot mistakenly turned off air-conditioning systems in a bid to hide his e-cigarette smoke, Chinese media quoted the country's civil aviation authority as saying Friday.
Earlier this week on Tuesday (10th July), it was reported that an Air China flight carrying 153 passengers and 9 crew members that flew from Hong Kong to Dalian, China suddenly dropped 25,000 feet (approx 7,600 meters) in 10 minutes during its journey.
Chinese officials said that the plane's co-pilot was vaping in the cockpit.
In desperation, the pilot reportedly hit the wrong switches, which dropped oxygen levels in the plane, triggering altitude warnings.
In a video of Flight CA106 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.
The flight landed safely in Dalian at 10:29 pm.
An initial probe by China's Civil Aviation Administration in China has shown that the co-pilot tried to turn off a fan to stop smoke reaching the passenger cabin without telling the captain, but turned off the air-conditioning unit instead.
Qiao Yibin, an official of the regulator's aviation safety office, said the shut-off triggered an alarm, prompting the crew to perform an emergency pressure relief procedure, which then released the cabin's oxygen masks.
It added that it was continuing to investigate the incident.
A clumsy co-pilot caused an Air China plane to plunge almost 20,000 feet midair when he pulled the wrong switch while trying to shut off an air recycling system - so he could vape in the cockpit.
The incident featured heavily on Chinese social media on Friday, with some commentators demanding harsh punishment and revocation of the pilot's flight licence.
Air China also said in a previous Weibo post on Wednesday it had a "zero tolerance" approach towards wrongdoing by any crew.