An emergency descent by an Air China aircraft after oxygen levels dropped in the cabin has been linked to a co-pilot who was smoking an e-cigarette during the flight, China's aviation regulator said on Friday (Jul 13).

The Civil Aviation Administration of China (CAAC) said in a press conference in Beijing that the drama was triggered when the co-pilot sought to turn off a ventilation system to prevent his smoke spreading into the main cabin, the respected news site Caixin said.

Smoking is not allowed aboard Chinese commercial passenger flights.

But the co-pilot accidentally switched off air-conditioning instead, leading to a decrease in cabin oxygen levels.

That set off an emergency warning system indicating that the 737 jet may have flown too high and instructing the pilots to quickly descend.

The Air China Boeing 737 aircraft was flying to the Chinese city of Dalian from Hong Kong, when it made an emergency descent to 10,000 feet (3,048m), during which oxygen masks were deployed, before climbing again to continue on to its destination.

Industry experts said the decision to climb and continue the flight was unusual given the oxygen masks had already been deployed and there was a risk another decompression event could occur after the one-time supply of 12 to 20 minutes from the oxygen masks was used up.

The CAAC has said there were no injuries to the 153 passengers and nine crew.

It added that it was continuing to investigate the incident.

Share This Post