How Does the Polar Vortex Affect Aircraft?

The polar vortex's icy temperatures are slamming into the Midwest and churning toward the East Coast, leaving thousands of flight cancellations in its path. But despite this travel strife that flyers usually associate with winter weather, there is at least one bright spot to flying in the cold.

Planes actually fly best when the air temperature is low. (If flights aren't canceled due to snow, ice or wind, that is).

Even though Chicago is colder than Antarctica right now, and people in Iowa have been advised to "avoid taking deep breaths, and minimize talking" outside because it is so frigid there, the intense Arctic blast is bringing great conditions for a flight, if not for the snow. It comes down to the simple physics of aviation.

"Airplanes perform best in cold weather," Patrick Smith, a Boeing 767 first officer for a US airline, told The Points Guy. "Cold air is denser than warm air which, at a given altitude, allows the engines to produce more power and the wings to produce more lift."

The opposite is true when the mercury rises and heat waves set in: Planes have trouble taking off and flights are actually canceled, like in July 2018, when 14 flights in London were canceled due to sweltering temperatures in the area. Higher temperatures cause air density to decrease, meaning a plane needs more runway than normal to generate adequate lift.

Of course, there are downsides to cold air for airlines' operations, too. "Some planes do have limits that prohibit operation when ground temperatures fall below a certain point (the complications involve starting the engines, cold-soaked oil and such)," Smith said. "But that's not really the issue here."

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The issues airlines will face during this week's polar vortex won't be about a plane's ability to fly, he added.

"They’re about the weather's impact on the support infrastructure," he said. "That is, the effects on airport personnel and the ground support equipment — the various people, vehicles and machinery that go into supporting an airline's operation. You can't load and unload the luggage, fuel the tanks or cater the cabins if the baggage carts and belt-loaders aren't working, the trucks aren't starting and employees are so cold they can hardly move."

So, here's hoping all ground personnel in Chicago have bundled up in their heaviest winter coats.