Here’s Why You Might See Fog And Mist Inside Your Airplane Cabin

If you’ve ever spot a thick layer of mist floating across the floor of your plane cabin, don’t panic. It’s (probably) not on fire.

Planes taking off from hot and humid climates often experience this unique “indoor weather.” That’s because the steamy air outside is being rapidly cooled and condensed by the plane’s onboard air conditioning unit. This creates waves of water vapor that can appear eerily like smoke.

“It is really nothing more than the very cold air coming out of the air conditioning forcing the air to release it’s moisture,” says retired Boeing 777 captain Dave Powell to The Points Guy.

While most planes have a special device called a water separator to prevent this situation, the machinery can’t always keep up when the outside conditions are especially warm and humid.

The good news is that this fog usually clears up within one to two minutes, so you won’t have to spend your entire flight in a sea of mist.