Breakdown: Why extreme heat can disrupt air travel

Published: Jun. 14, 2022 at 9:45 AM CDT
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MEMPHIS, Tenn. (WMC) - Having your flight delayed due to severe storms or winter weather is not unheard of, but did you know that periods of extreme heat can also delay or cancel your trip?

A situation like this might be confusing to airlines customers, as they may not understand why their flight is impacted on a bright, sunny day.

To understand why air temperature can make or break a functional flight, you have to know that pilots and flight engineers think of the gas-filled atmosphere instead as a fluid: Planes interact with the air similar to how we interact with water when we float.

As a plane cruises down a runway, it pushes against the air. Due to one of the main rules in physics — every action comes with an equal and opposite reaction — the air pushes back. Some of that response translates into “lift” (the official name for the force that pushes planes into the sky).

But higher-than-expected temperatures interfere with how the air pushes back.

Like with water, adding heat to air separates the molecules and forces more space between them.

When gases warm up, the atoms and molecules move faster, spread out, and rise. That’s why steam...
When gases warm up, the atoms and molecules move faster, spread out, and rise. That’s why steam coming off a pot of boiling water always goes upward. When air is colder, the gases get slower and closer together. Colder air sinks.(NOAA)

Hot air makes it harder for planes to fly. Warm air expands and is less dense—it’s why hot air balloons go up. It also means the air is thinner so it takes more power to get the lift that allows a plane to take off.

Under hot conditions, it takes more fuel, which is heavy, to lift the same amount of passengers and cargo. Researchers at Columbia University predict by 2050, there could be four times as many weight restriction days at the most at-risk airports in the United States.


  1. To deal with more frequent and hotter heat waves, U.S. airlines may have to move long-haul summer flights to early morning or late evening when it’s cooler. But that can create havoc with scheduling and require passengers to fly at inconvenient times.
  2. Another option is to lengthen runways or move hubs to airports with longer runways so planes have the distance needed to reach takeoff speed.
  3. Other solutions include carrying fewer passengers or cargo when temperatures are high, shifting to lighter airplanes, or installing more efficient engines.

Extreme heat events are increasing in frequency and duration in the United States. In the 1960s there were an average of two per year. By the 2010s the average was six.

They’re also lasting longer. The average heat wave in major U.S. urban areas is now four days long, a day longer than the 1960s, according to the Environmental Protection Agency. The season for heat waves is now 47 days longer than it was 60 years ago.

Last month’s United Nations report on climate change predicted even more intense heat waves to come.

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