Bigger jets like Boeing 737s and Airbus A320s have higher operating thresholds (126 and 127 degrees, respectively), he said. All three of those maximum temperatures are specific to the Phoenix airport; aircraft have different maximum operating temperatures depending on a variety of factors, including airport elevation.
But even though bigger planes weren’t affected, Mr. Feinstein said, American decided to give passengers on any flight to or from Phoenix between 3 p.m. and 6 p.m. — the hottest part of the day — the option to change their trips. Over all, more than 350 flights were potentially affected by the hot weather in Phoenix.
Robert Mann, the president of airline industry analysis firm R. W. Mann & Company, said that although airlines were working to become more efficient now, they were not doing much to prepare for the longer-term effects of climate change. “In a world where they’re focused on near-term issues, the glacial rate of environmental change is not within their fleet-planning horizon,” he said.
Mr. Feinstein of American Airlines referred questions about the effect of climate change on flying to an industry trade group, Airlines for America. The trade group provided its Earth Day statement describing its members’ efforts to become more environmentally friendly by using more fuel-efficient engines and modifying planes to be more aerodynamic.
How Higher Temperatures Affect Flying
As temperatures increase, air density decreases, which reduces lift and makes it harder for airplanes to take off. To address this, airlines could reduce airplane weight (by loading fewer passengers and less fuel or cargo) or schedule departures for cooler periods of the day.
Aviation is a major producer of carbon dioxide, responsible for about 2 percent of human-made emissions each year.
Researchers are just beginning to explore how climate change affects aviation and planes’ ability to fly. Because there is so little data available and so many factors at play — aircraft design, airport size and location, the weight of passengers and cargo, to name just a few — it can be hard to attribute any one service disruption to global warming.
Depending on their locations, airports may experience the effects differently. High-altitude airports like Denver have thinner air by nature, so lift is even more affected by higher temperatures.
La Guardia Airport in New York could also be affected, even though it is at sea level. La Guardia has a short runway relative to other major commercial airports, and on particularly hot days that can be a problem: Planes might not have enough distance to achieve the speed and lift needed to get airborne.
“Typically in the hotter days of the summer, you may have to bump payload, which includes cargo and/or passengers,” said David Wilhelm, a senior dispatch manager at Southwest Airlines. Reducing weight allows a plane to take off with less lift.
La Guardia, because of its short runway, already forces many planes to reduce their weight, regardless of the weather. A Boeing 737, for example, has to cut its maximum payload by a thousand pounds for a successful departure. That restriction increases on hotter days, up to 15,000 pounds when the temperature hits 91.4 degrees.
Restrictions like these are determined by individual airports and airlines, and not by a standardized industry regulation. American Airlines consults National Weather Service data and plugs it into a formula to calculate air density to determine if conditions at a given airport are suitable for takeoffs and landings.
In 2015, Radley Horton, a research scientist at Columbia University’s Earth Institute, published a joint study with a Ph.D. student, Ethan Coffel, on the effect of extreme heat on aviation. The conclusion: “We can say with confidence that there will be more weight-restricted days, and larger weight restrictions,” he said.
Already, since the 1980s, airports have seen an increasing number of weight-restricted summer days, their research found. “One thing that’s become abundantly clear,” Dr. Horton added, “is this is an underexplored area.”
How Stronger Winds Affect Flying
At cruising altitudes, winds are becoming stronger and more turbulent. Since the jet stream generally travels from west to east, this means that flight times could get longer heading westbound and shorter heading eastbound. This would probably increase overall travel time and fuel consumption across the industry.
PREVAILING WIND DIRECTION
Variable Polar
Jet Stream
Westbound flights
will be slowed.
Eastbound flights
will be sped up.
Flights are also likely
to become bumpier, particularly
eastbound flights, as stronger winds
create more turbulence.
PREVAILING WIND DIRECTION
Westbound flights
will be slowed.
Eastbound flights
will be sped up.
Variable Polar
Jet Stream
Flights are also likely
to become bumpier, particularly
eastbound flights, as stronger winds
create more turbulence.
The study examined conditions at four airports: La Guardia; Ronald Reagan Washington National Airport, which also has relatively shorter runways; Phoenix Sky Harbor International Airport; and Denver International Airport. Some airports, like Denver, could counteract rising temperatures by extending their runways. That option is less workable for a location like La Guardia, however, as it is hemmed in by the East River.
As global temperatures continue to rise, some of the heaviest planes on the longest flights may eventually be unable to depart during the hottest part of summer days, Dr. Horton said. Like an ocean liner waiting for the right tide to leave port, airplanes may be grounded until the air is cool and dense enough for takeoff at full capacity.
He also pointed out that a no-fly window of even a few hours at a particular airport could have a ripple effect across airline operations while further squeezing airlines’ already tight profit margins.
Extreme heat on the ground also affects airport workers; loading and unloading luggage and servicing planes between flights could become more onerous. In Phoenix this week, American Airlines set up cooling stations — air-conditioned tents on the tarmac — for its employees.
Places like Phoenix, already known for summer heat, are measurably warming up. Data from the National Centers for Environmental Information show that every year since 1976 has been hotter than the city’s historical average. Seven of the 10 hottest years on record there have been in the past decade.
With forecasts predicting record-breaking temperatures in Phoenix on Tuesday — and some flights being canceled pre-emptively — many passengers stayed away from the airport entirely. Security lines had almost no wait. The terminals were so empty, one traveler was spotted riding his bike through the airport.
Allison Thomas, a 28-year-old college student, said she had endured three flight cancellations as she tried to return home to Seattle. “I’m so tired!” she said, but added that she felt lucky that she had family in town. “Other people had to go to hotels.”
After her third cancellation, Ms. Thomas finally gave up. She decided to drive to San Diego to try to catch a flight there — despite the risk that planes might not take off there, either.
One of the most important changes for global travel involves the jet stream, the powerful upper-atmosphere winds that aircraft must navigate. Jet stream patterns influence flight routes, travel time and airline fuel economy because long-distance air corridors are designed to take maximum advantage of prevailing weather patterns, which give a tailwind to eastbound flights and a headwind to westbound ones.
