Hotter, Thinner Air Can Reduce Aircraft Performance, Forcing Airlines to Remove Passengers or Cargo, Carry Less Fuel or Wait Until Temperatures Fall
Most airline passengers know thunderstorms, snow and strong winds can delay a flight. A clear summer afternoon, however, may not seem like a warning sign.
Extreme heat can disrupt air travel even when there is not a cloud in the sky. As temperatures rise, the air becomes thinner, making it harder for aircraft wings to generate lift and jet engines to produce the thrust needed for takeoff.
The problem is familiar at airports in desert climates, but it can also affect major Texas airports during prolonged stretches of triple-digit temperatures. Airlines may impose weight restrictions, delay departures until cooler hours or reduce passenger, cargo and fuel loads to ensure aircraft can take off safely.
Why Extreme Heat Makes Takeoffs More Difficult
Hot air expands and becomes less dense than cooler air. That reduced density affects both an aircraft’s wings and engines.
“There is a science behind all this,” said Ross Aimer, a retired United Airlines captain and CEO of Aero Consulting Experts. “You can’t deny the science of flight and what it takes for an airplane to operate.”
Aimer compared the challenge to athletes competing at high elevations, where the thinner air makes physical activity more difficult.
“Just like human beings, jet engines require lots of cool, dense air to perform well,” he said.
Before departure, pilots and airline personnel calculate whether an aircraft can take off safely based on its weight, the outside temperature, the airport’s elevation and the available runway length, retired Delta Air Lines captain Alan Price said.
Higher-elevation airports already operate in thinner air, meaning flight performance can be affected at lower temperatures. Short runways create another complication because aircraft need additional distance to build enough speed during hot weather.
If the calculations show a plane cannot safely depart as scheduled, an airline may remove cargo, reduce the amount of fuel onboard, arrange an additional refueling stop or ask passengers to take a later flight. Airlines may also wait for temperatures to fall.
There are situations, however, when reducing the aircraft’s weight is not enough.
“At some point, the numbers just don’t make sense,” Aimer said. “You could roll down a runway as long as you want, and you still can’t take off.”
Airlines May Ask Passengers to Give Up Seats
According to the Associated Press, Las Vegas recently demonstrated how extreme temperatures can interfere with air travel.
American Airlines offered compensation to customers who volunteered to leave a July 24 flight from Harry Reid International Airport after the temperature reached 114 degrees. The airline said reducing an aircraft’s weight is a standard safety practice in hot-weather destinations when conditions require it.
Airlines have encountered similar problems for years.
American Airlines canceled several regional flights between Palm Springs, California, and Phoenix during extreme heat in June 2016. The following year, the carrier canceled dozens of regional flights in Arizona as Phoenix temperatures approached 120 degrees.
Some airlines removed passengers from flights at Denver International Airport in July 2018 when the temperature reached 98 degrees. Delta Air Lines also sought volunteers to leave a plane in Las Vegas during an excessive heat warning in July 2023 because of temperature-related weight restrictions. The flight was eventually canceled.
The Federal Aviation Administration does not have one maximum temperature that applies to every takeoff. Operating limits depend on the aircraft’s make and model, its total weight, airport elevation and other conditions.
Texas Airports Face Heat Beyond the Runway
During severe Texas heat waves, flight operations are only part of the challenge.
Ramp workers loading luggage, directing aircraft and servicing planes can spend hours on pavement where temperatures are significantly hotter than the official air temperature. Airlines and airports may rotate crews more frequently, establish hydration stations and require cooling breaks to reduce heat-related illnesses.
Terminal cooling systems can also struggle when outdoor temperatures remain in the triple digits. Large crowds, open jet bridges and constant foot traffic allow warm air into terminals, increasing pressure on air-conditioning systems.
Airports are especially vulnerable to the urban heat island effect because they contain large areas of pavement, limited shade and constant activity from airplanes, vehicles and cooling systems that release additional heat.
Jennifer Brady, a data scientist with Climate Central, said airports contain “all of the elements” that can make them some of the hottest spaces within a city.
Extreme surface heat can also contribute to rapidly developing thunderstorms. Those storms may result in Federal Aviation Administration ground stops that produce delays extending far beyond the airport where the weather began.
Climate Change Could Increase Flight Restrictions
Researchers say rising global temperatures could make heat-related flight delays and weight restrictions more common.
A 2017 study from researchers at Columbia University, NASA’s Goddard Institute for Space Studies and the Logistics Management Institute projected that some airports could face weight restrictions on 10% to 30% of flights departing during the hottest part of the day by the middle of the century if greenhouse gas emissions continued rising.
The study examined 19 airports and found that facilities with shorter runways, higher elevations and hotter climates faced the greatest risk.
A more recent study examining four European airports concluded that projected temperatures could force aircraft to remove weight equal to approximately 10 passengers per flight by 2065.
The number of extremely hot days has already increased at several major U.S. airports.
Phoenix Sky Harbor International Airport averaged 43 days per year with temperatures of at least 110 degrees from 2020 through 2025, according to an Associated Press analysis of weather station data. That was more than three times the average recorded during the middle of the 20th century.
Las Vegas averaged approximately 18 days per year at or above 110 degrees during the same period, more than twice the annual average recorded from the 1940s through the 1960s.
Palm Springs International Airport averaged 55 days per year at or above 110 degrees during the 2020s, an 83% increase compared with the 2000s.
For passengers, extreme heat may increasingly belong alongside thunderstorms, snow and high winds as a reason to prepare for travel disruptions. A sunny sky may look safe, but when temperatures climb high enough, the physics of flight can still keep an airplane on the ground.
