An Air China co-pilot apparently forced his plane to descend about 20,000 feet when he flicked the wrong switch to hide his vaping from passengers, CNN reports. Chinese aviation officials say the co-pilot, who remains unnamed, tried to shut off air recycling fans to prevent smoke from spreading to the passenger cabin on the Tuesday run from Hong Kong to Dalian, China, but flicked off the air conditioning by mistake. That lowered oxygen levels and set off altitude warnings, forcing pilots to descend immediately. Oxygen masks were also deployed during the emergency descent—photos of which later popped up on Chinese social media and can be seen at Australia's News Network. (Or see this passenger video on YouTube.)
After descending 19,600 feet in under nine minutes, pilots realized the mistake, re-activated air conditioning, and brought the flight to its regular altitude—but oxygen levels remained subpar for the rest of the flight, the BBC reports. Air China fired the whole flight deck crew and suggested the Civil Aviation Administration of China strip their licenses. For its part, the CAAC is investigating. On the upside, a passenger on flight CA106 says all 153 passengers appeared calm throughout: "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," Hoby Sun tells CNN. "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."