Fog in Your Airplane Cabin? No Worries, It’s Cool (Literally)

Aug 8, 2018

This post contains references to products from one or more of our advertisers. We may receive compensation when you click on links to those products. Terms apply to the offers listed on this page. For an explanation of our Advertising Policy, visit this page.

There are plenty of nervous flyers. We get it, airplanes can be a bit scary if you aren’t familiar with what’s going on.

When Twitter user Gavin Polone  stepped aboard a flight recently, it looked like the cabin was filling with smoke, and, feeling uneasy about the situation, he took to social media to ask others about it:

And he has a point asking: Fire and smoke in aviation are extremely serious. Onboard fires, for example from cigarettes, can bring down planes. It’s why “tampering with, disabling or destroying a lavatory smoke detector” is a serious federal offense in the US. Smoke in the cabin is a pretty automatic trigger for an immediate diversion and, on the ground, an evacuation.

But as it turns out, while this scene may appear serious, it’s normal, totally safe, and in some climates it happens all the time.

That’s because you’re not looking at smoke in the video above. Gavin is seeing mist — hot and humid outside air rapidly condensing upon contact with the aircraft’s onboard air conditioning unit that creates billows of water vapor. In this specific instance, there’s so much water vapor because the air conditioning is blasting, the doors are open and we’d bet the flight crew cranked up the AC just a few minutes prior, and water vapor is the result of all that hot and humid air mixing with air that’s much cooler.

Dave Powell, a retired Boeing 777 captain and now Dean of the College of Aviation at Western Michigan University, helped us understand.

He explained, “it is really nothing more than the very cold air coming out of the air conditioning forcing the air to release it’s moisture.” He reiterated that it happens “all the time” when flying and out of hot and humid locations and crews are looking to cool off the aircraft.

Consequently, you’ll experience this phenomenon most frequently when departing from hot and humid climates, as the blasting air conditioning units cause the hot, heavy air to condense and turn to mist. And unlike arriving flights, which have been climate-controlled for hours already during the flight, they’ve been sitting on the ground, doors open and humidity settling inside. This isn’t unique to aircraft either: A support page for GE air conditioners outlines this same effect — the worse the humidity, the more intense the mist, and it closes with a comforting conclusion: “The fog or smoke should disappear rapidly, usually in less than a minute or two, as the air conditioner removes the humidity from the air and the room air becomes cooler.”

Most planes are even equipped with something called a water separator to prevent this from happening often, but even that can’t keep up with conditions in especially hot and humid climates. A simple rule of thumb: if you board an airplane filled with what appears to be smoke, and the cabin crew and pilots are conducting business as usual, it’s a pretty safe bet it’s not toxic fumes that’s filling the cabin.

Editorial Disclaimer: Opinions expressed here are the author’s alone, not those of any bank, credit card issuer, airlines or hotel chain, and have not been reviewed, approved or otherwise endorsed by any of these entities.

Disclaimer: The responses below are not provided or commissioned by the bank advertiser. Responses have not been reviewed, approved or otherwise endorsed by the bank advertiser. It is not the bank advertiser’s responsibility to ensure all posts and/or questions are answered.