Sweltering Planes. Baking Runways. How This Heat Is Testing Summer Travel.

Travelers and crew members endured sweltering temperatures as their plane waited on the tarmac. ​Carriers have supplied baggage handlers with ice and extra breaks. Airlines have lightened jets to aid takeoff in the lighter air.

A heat wave that has engulfed swaths of the U.S. in recent weeks is​ putting up fresh challenges for airlines amid the hectic summer travel season. ​ 

Christopher DeBoer was a passenger on Delta Flight 555, scheduled to fly ​J​uly 17 from Las Vegas to Atlanta. The flight was on the ground for about three hours in the 111-degree heat before it was canceled.

“It was incredibly uncomfortable,” he said. “The longer we sat there, people were getting warm. You could kind of smell the mustiness.” 

The Transportation Department is investigating​ the incident. Delta Air Lines said it is cooperating with the investigation and looking into what led to the uncomfortable temperatures in the cabin. 

For airlines that have navigated a spate of disruptive summer storms, the record-breaking heat hitting parts of the U.S. is creating additional difficulties. Workers who sling bags outside need more frequent breaks. When temperatures surge, planes sometimes need longer runways or must reduce weight to take off in the less dense air.  

Delta, American Airlines, United Airlines, Southwest Airlines and other carriers said workers are encouraged to take breaks and keep hydrated during the hot summer months. American Airlines said it has had a “very small number” of flight diversions and delays related to high temperatures, but has worked to avoid a more significant impact. 

“We’re really taking this seriously, and we’re going to have to as we go forward,” American Airlines Chief Executive Robert Isom said during an earnings conference call last week.

Carriers say they work to ensure planes have appropriate air conditioning before passengers board. They pump chilled air through hoses at the gate to cool cabins and can run auxiliary power units for air conditioning, particularly when planes are taxiing.   

Passengers and crew members at times still complain that planes can start to feel like ovens as they linger on the ground with the sun beating down.

“It’s a consistent issue. It comes up every single summer,” said Taylor Garland, a spokeswoman for the Association of Flight Attendants-CWA, which represents flight attendants at several airlines. Auxiliary power units can break or aren’t turned on soon enough, and airports might not always have enough cooling units, she said.

AFA in 2018 petitioned the Transportation Department to set cabin-temperature standards. That year the group, along with the union that represents Southwest Airlines’ flight attendants, launched an app for flight attendants to report extreme temperature readings. No limits have been set.

A provision in a bill to reauthorize the Federal Aviation Administration, passed in the House last week, calls for a study of the effect on passengers and crew when temperatures inside planes reach extreme levels. Companion legislation set to be debated in the Senate includes a similar measure.

Following the ​July 17 flight, ​Delta awarded passengers 20,000 SkyMiles and refunded their fares, in addition to providing meal and hotel vouchers to the customers stuck in Las Vegas overnight.

“We recognize that you endured a very poor cabin experience due to a taxi delay and high cabin temperatures attributable to the scorching temperatures in the Las Vegas area on your day of travel,” the airline later wrote in a note to passengers. “We deeply regret the conditions on board flight 555.”

A flight attendant and passenger were treated at a local hospital, a Delta spokesman said.

A domestic flight that has been delayed on the ground has three hours before it has to start moving to a location where passengers can exit, and airlines can rack up fines for violations. The Delta flight’s time on the ground included periods when it had returned to the gate, the airline said. 

Carriers also have to maintain a “comfortable cabin temperature” during lengthy ground delays, but regulations don’t set a specific temperature range.  

The Transportation Department’s inspector general has said that the lack of a set definition of a comfortable cabin temperature has made it difficult for the department to enforce those rules, and recommended nearly a decade ago that the department enshrine the definition in regulations. 

In 2018 the DOT fined Allegiant Air $225,000 after receiving complaints that cabin air temperatures became uncomfortable on a number of delayed flights in the two previous years. The department wrote in its ruling that it considers written passenger complaints, crew-member statements, temperature readings, reported medical incidents and other factors to determine whether an airline lived up to its obligations. 

Allegiant said at the time that the affected flights were subjected to outside temperatures sometimes rising above 110 degrees Fahrenheit, which made it difficult to cool the cabin despite the airline’s use of air-conditioning carts, ground power units and other measures. 

Allegiant, based in Las Vegas, said that its fleet is now made up entirely of Airbus jets with better climate control than the older planes it was still flying until 2018 and that it hasn’t experienced issues with hot cabins this summer. Allegiant’s flight crews recently started using an app to track tarmac delays so planes don’t leave the gate earlier than they have to, letting them remain connected to a source of cool air as long as possible. 

“The goal is to take off quickly after pushing back, and if that’s not possible, we will delay a flight for the sake of passenger safety and comfort,” a spokeswoman said.  

Write to Alison Sider at [email protected]