SEATTLE — So this just happened: an Air China co-pilot who was smoking an electronic cigarette in the cockpit caused the plane to drop nearly 20,000 feet after flipping what he thought was the switch for the air recycling fans.

According to CNN, the unnamed co-pilot was trying to turn off the fans to prevent the vapour from spreading into the cabin. Instead, he flipped the wrong switches, causing a drop in oxygen levels that triggered altitude warnings just 30 minutes after takeoff.

As a result, Air China flight CA106, which was en route from Hong Kong to Dalian, China last Tuesday, dropped from over 32,800 feet to 13,100 feet in less than nine minutes. In a video obtained by the Beijing News, oxygen masks are seen hanging from overhead compartments while a flight attendant walks down the aisle to check on passengers.

In total, there were 153 passengers and nine crew members onboard the flight.

Multiple Chinese state media outlets reported that the plane eventually rose back to around 24,600 feet and continued to Dalian with a less-than-adequate oxygen level in the cabin.

Qiao Yibin, a senior official from the Civil Aviation Administration of China (CAAC) said that “severe punishment in accordance with laws and regulations” would be handed down. Air China fired the entire flight deck crew put forth a recommendation to CAAC to revoke the pilot’s licence upon completing its investigation.