Over three days in late June, American Airlines canceled 57 regional flights out of Phoenix due to extreme heat of 120 degrees Fahrenheit.
More heat waves in the future could mean flights get canceled, delayed or have to lose some weight. That weight could be you.
In the aviation business, really hot days are called “weight restriction days” because when it’s hot, fully loaded planes can’t get off the ground. There’s only three ways for a plane to lose weight — fuel, cargo, or passengers.
In a 2015 study, researchers at Columbia University predicted that by 2050 there could be four times as many weight restriction days at the most at-risk airports in the United States.
On the hottest days and longest flights, that potentially could mean dozens of passengers and their luggage are left waiting in the terminal.
To take off, a plane has to reach a certain minimum speed. On hot days and at high elevations, that minimum speed increases.
“High elevation and high temperature mean less molecules of air for the plane to push off of,” explained Radley Horton, a climate scientist at Columbia who was involved in the study.
Longer runways can help, allowing pilots to attain a faster speed.
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But when it’s too hot for a plane to take off, airlines must choose between canceling the flight, waiting until it’s cooler, or cutting back on weight. That’s why long flights out of the Middle East and parts of Central and South America routinely are scheduled for late in the evening or overnight.
The Columbia researchers found the number of weight restriction days already has increased since 1980. Some airports in the U.S. have adopted measures to deal with extreme heat.
Larger planes are better equipped to deal with weight restrictions. A standard 737 jet carries over 20 tons of fuel — and most flights do not require a full tank, Nolen said.
“These calculations happen every day, they’re computerized,” he said.
Smaller, older aircraft used for regional flights have an added challenge. Those models don’t stand up to extreme heat as well — and so, as with the flights out of Phoenix last month — are much more likely to be canceled.