How a Pilot Smoking in the Cockpit Caused His 737 to Lose Pressure and Descend 21,000 Feet

I’ve held off writing about the Air China flight which lost cabin pressure and quickly descended 21,000 feet because there were missing pieces to the story that just didn’t make sense. The incident was being blamed on a pilot smoking in the cockpit.

While it’s understandable that a pilot doing so wouldn’t want to be outed out of fear for their job, it was not clear how the smoking was in any way related to the incident. Until now, that is.

Flight CA106 from Hong Kong to Dalian, China was climbing to 35,000 feet while southwest of Shantou, China when the Boeing 737 initiated an emergency descent as a result of the loss of cabin pressure. Oxygen masks dropped. The plane leveled off around 10,000 feet, and then the crew brought the aircraft back up to around 24,000 feet.

The aircraft continued on to its destination, and landed safely around 3 hours after the incident in Dalian, China. The airline placed both pilots under investigation. They believed there was smoking going on on the flight deck, adn this led to the pressurization problem which then caused them to initiate an emergency descent.

So how on earth would smoking have done that? Apparently “while smoking in the cockpit the crew mistakenly shut down both bleed air supplies causing the cabin to lose pressure.”

The crew believed they lacked control over cabin pressure so brought the plane to a lower altitude. However they discovered, after leveling off around 10,000 feet, that they had just shut off the bleed air systems. They reactivated the systems, brought the cabin back to pressure, and climbed again to 24,000 feet.

Preliminary investigation by the Chinese Civil Aviation Authority suggests that the first officer was vaping with an electronic cigarette. Electronic or otherwise he didn’t want vapor or smoke to enter the cabin, revealing what he was up to, so he shut down the cabin re-circulation fan. He didn’t tell the captain he was doing it. Except that instead of shutting off the fan he shut down the bleed air. Oops.

And to potentially make matters even worse, when the plane descended it wound up in a dangerous trajectory in conflict with a private aircraft which then had to take evasive maneuvers.

About Gary Leff

Gary Leff is one of the foremost experts in the field of miles, points, and frequent business travel - a topic he has covered since 2002. Co-founder of frequent flyer community, emcee of the Freddie Awards, and named one of the "World's Top Travel Experts" by Conde' Nast Traveler (2010-Present) Gary has been a guest on most major news media, profiled in several top print publications, and published broadly on the topic of consumer loyalty. More About Gary »

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  1. I have been on two Chinese-airline flights where smoking was definitely happening in the cockpit. I was in business class both times and no one was smoking in the cabin or in the bathrooms.

  2. Wow this story keeps getting more horrific. Didn’t hear about evasive manoeuvres before.

    In addition to all that you listed, don’t forget the fact that the oxygen generators (which supply the masks that descended after the copilot essentially cut off the air supply) only last for 15 mins. So instead of diverting they re-ascended to 24,000 ft using an aircraft that had no more emergency oxygen supply for passengers and cabin crew.

    This is a safety failure on so many levels…. since the early 2000s China’s aviation sector has done a good job of growing exponentially without spectacular accidents but this is really crazy… everything from CRM to basic pilot training needs to be examined – for Air China too! The flagship airline.

  3. It is my experience that in parts of China (all the parts I’ve been to), smokers believe they can smoke absolutely anywhere they want, whether it’s allowed or not. I’ve been in (so called) 5-star hotels where there are clear “no-smoking” signs in all the public indoor spaces (restaurants, bars, lobby, elevators, hallways) and the hotel guests smoke as if its 1960 and the world is their ashtray – and they just ignore the signs. I complained to the manager at a 5-star hotel about this behavior which I was simply not used to, and really grossed me out. I asked that he have his staff stop the smoking in the restaurant where I had to get my included breakfast. The manager just laughed at me: “You’re so naive. The government gets a huge amount of revenue from tobacco taxes, and they will do nothing about enforcement. Nobody will have my back if I try to do any enforcement in my hotel. And you’ll find this problem is the same at all the hotels.” (I was pretty angry at the time, but I now believe, with more experience in China, that the hotel manager was sincere and correct. And for the record, he sent to my room a very nice fruit bowl with a nicely written apology, saying again that there’s nothing he can do about the other guests smoking.) My only recourse I think is to just suck it up if I want to do business in China. I’m not surprised that even pilots would have such an attitude (without serious and necessary counciling by their management). When you’re an addict, you judgement is defective if anything gets between you and your fix. Because tobacco consumption is so widespread in China, I’m guessing that the government might also be concerned about the social unrest factor that might go along with any serious anti-tobacco campaign. So they are kind of stuck with this selfish and disgusting habit for the time being.

  4. In other parts of the world, smoking is simply not the culturally offensive atrocity that it is in the States. Travelers would be well-served to recognize that before expecting standard, States-like behavior from others outside the US on things like smoking.

  5. @Raj – I don’t give a flip if someone wants to suck on cancer sticks on the ground, so long as it doesn’t become an olfactorily offensive atrocity.

    In the air is a different story — not just because of the odor, but because of safety issues as well. This really doesn’t have anything to do with finding smoking “culturally offensive.”

  6. Totally agree. The thought that smoking in some places could be or should be off limits is foreign to more than someone might think. “What do you mean I can’t smoke here?” It’s not obvious to all. That’s all.

  7. funny story.

    I’m 8 years old, or maybe 9, or maybe 7. at any rate that means it’s the mid-1960s

    My uncle works for Pan Am, and the Pope’s plane is at the Pan Am maintenance facility in JFK about to fly to Laguardia to pick up the Pope. So my uncle gets us a ride on the Pope’s plane for short haul.

    and of course with my Uncle being a navigator, the cockpit door is left open and we get the tour.

    all of the crew light up and one of them then stands up and OPENS A HOLE AT THE TOP OF THE COCKPIT !!!! he then jimmies it open with a pen.

    I am terrified. … I am no six or seven or eight-year-old dummy God damn it. …. I have seen that damn James Bond movie! I have seen a guy get sucked out of an airplane! And I am quaking.

    I later found out the little hole with the flap on it iis where they screw in an octant, and jamming the octant hole open was pretty much standard operating procedure for smoking Pilots. taking sightings with an octant was the way Navigators navigated in the 1960s.

    still can’t figure out how they would open that hole with the pressure differential at altitude

  8. I’m more (most?) bothered by the error the pilot made in trying to change the venting system – if he couldn’t do that correctly it kind of says something about his over all skills. And what else is going on in that the pilots are not telling each other.

  9. Raj: Those who rarely get out of their comfort zone don’t understand that US standards don’t prevail world-wide (and usually that’s a relief). I had a similar experience, though not so dangerous, in Portugal. I was on a first class bus with No Smoking signs all over the place but the guy seated next to me lit up a big, smelly cigar. When I pointed the No Smoking signs, he just shrugged. So I complained to the driver and got the same response. He said there were plenty of empty seats and I could move wherever I wanted.

  10. It was a first officer(co-pilot). Having trained some Chinese airline crews(seven different airlines to be exact), the first officers are very low-time inexperienced pilots. One of the biggest challenges in training these guys and gals is their “fast” hands in the cockpit. They push buttons and throw switches without looking or understanding what they are doing. As for the cigarette smoking in the cockpit. This is common among the Chinese airlines as well. I have had this riding in business class on China Eastern. Remember China Tobacco(owned by the government is the largest tobacco company in the world). Fly these airlines at your own peril.

  11. Yeah, sometimes cultural differences just don’t translate in the time that it takes to takeoff and land.

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