Why would turning off the air con cause the plane to plummet? What does that have to do with vaping? Sounds to me like he was fire for being a bad pilot.
He turned off the wrong switches --oops
"A senior official from the Civil Aviation Administration of China (CAAC) told reporters Friday that, without notifying the pilot, the unnamed co-pilot was trying to turn off air recycling fans to prevent the vapor from spreading into the passenger cabin.
Instead, he toggled the wrong switches, which were close to his intended target, leading to a drop in oxygen levels that triggered altitude warnings."
(source
Officials: Vaping Co-Pilot Caused Plane to Plummet)
and they are in big trouble (rightfully so)
"
Qiao Yibin, the CAAC official, promised to hand down “severe punishment in accordance with laws and regulations,” if the regulator’s final conclusion on the incident matches its initial finding.
Air China fired the entire flight deck crew and suggested CAAC revoke their pilot’s licenses upon completing its investigation, the country’s flag carrier said Friday night in a statement."