This Is Exactly How Cold It Has to Be to Keep a Plane from Flying

By Madeline Wahl, Reader's Digest

Airlines deal with a lot of angry, exhausted travelers due to flight delays and cancellations. While snow, sleet, and icy conditions are definitely culprits in winter, frigid temperatures aren't. If you want to avoid as many delays as possible, this is the best time to fly.

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Almost 70 percent of all delays are caused by inclement weather in a given year, according to the Federal Aviation Administration, and delays also have significant monetary consequences, including costing both travelers and airlines billions of dollars every year.

But, is there an exact temperature that makes it too cold for a commercial airplane to fly? "There is not a specific temperature," says Tom Haines, Senior Vice President of Media, Communications & Outreach at the Aircraft Owners and Pilots Association (AOPA). "However, extreme cold on the ground can mean that around minus 20 F or so, the oil in the turbine engine may become so thick that it would be difficult to start the engine. Therefore, at around that temperature the operator would use hot forced air into the engine to warm the oil before starting. Once running, the engine can operate in much colder conditions." Make sure you know the potentially scary reason why airplanes dim the lights before takeoff.

When flying, it's important to check the safety of the aircraft, including knowing when jet fuel begins to freeze. "Jet fuel begins to gel in extreme conditions and does eventually freeze, typically at minus 40 or so, although additives can be included that reduce that further," says Haines. "Aircraft at cruising altitude will often experience temperatures of minus 50 to minus 70 F for hours on end."

Generally, engines like cold weather. Since cold air is denser than warm air, engines provide more power because there are more oxygen molecules. Similarly, "dense air makes the wings more efficient as there are more air molecules flowing over the wings, which improves takeoff and climb performance in cold weather," says Haines.