An Air China flight earlier plunged 3,000 metres this week after a co-pilot made an error while smoking an electronic cigarette, reported the Civil Aviation Administration of China (CAAC) on Friday.
During a flight on Tuesday from Hong Kong to Dalian, an Air China co-pilot accidentally switched off the plane's air conditioning to clear smoke out of the pilot's cabin when he finished smoking.
He intended to switch off the air circulation, according to China Daily, to prevent smoke from entering the main cabin.
However, his actions led to a loss in air pressure and the plane made a sharp descent, triggering the release of oxygen masks.
The flight, however, made it safely to Dalian on Tuesday night, with 153 passengers and nine crew on board, according to China Daily.
The co-pilot has yet to be identified by the CAAC. Smoking is prohibited on Air China flights.
