ATLANTA — A power failure at Hartsfield-Jackson Atlanta International Airport on Sunday disrupted operations at the busiest airport in the world, forcing the cancellation of more than 1,150 departing or arriving flights and stranding travelers on planes on the tarmac for hours, the authorities and passengers said.
The power failure at the airport, a major hub for domestic and international flights, sent a ripple of disruptions across the country, affecting flights in Chicago, Los Angeles and elsewhere. There were signs the problems would linger into Monday, as Delta Air Lines announced Sunday evening that it planned to cancel 300 flights the next day.
Many flights in the air were diverted when the power went out, and the United States Customs and Border Protection said on Twitter that international flights destined for Atlanta were rerouted to other airports.
Georgia Power, the utility provider for the airport, said early Sunday evening that the failure, which occurred around 1 p.m., might have been caused by a fire that damaged an underground electrical facility and cut power to a substation serving the airport. It also damaged a backup system that provides power to the airport in emergencies.
Utility workers restored power to all terminals at the airport by midnight, the city said. The airport is the busiest in the world for passenger traffic, serving more than 104 million passengers last year, according to Airports Council International. The failure affected at least 30,000 people, airport officials said.
Mayor Kasim Reed said the authorities did not know yet what caused the fire, which produced intense flames and noxious fumes that prevented utility workers from accessing the tunnels for several hours. He said they were investigating whether someone had tampered with the electrical system.
The mayor said the airport would resume commercial flights after power is fully restored and the police complete a security sweep. “Once all our systems are up and operational, we can get everyone back on their planes as quickly as possible,” Mr. Reed said at a news conference on Sunday night.
As the sun set on Sunday, the airport descended into darkness, and at least three airlines canceled their remaining flights headed to Atlanta. Passengers waited in long lines to catch taxis and public transportation. With no announcement system working and few uniformed airline employees available, passengers said they did not know whether they should stay at the airport or how and when they could reschedule their flights.
Travelers in the south terminal were told to leave the gates and return to the other side of the security checkpoint. But with few hotels with rooms available, many passengers rested on the baggage carousels.
The failure also cut off basic amenities that require electricity, including some water fountains and toilets that rely on electronic motion sensors, passengers said on social media.
Passengers were getting some relief. Chick-fil-A, the fast-food chain, planned to provide food for stranded passengers, the mayor said. The city also opened the Georgia International Convention Center, which can hold up to 10,000 people, and was offering rides there from the airport. But security personnel outside the convention center said that only about 50 people had arrived, and that they were not expecting many more.
Matt Becker said that after his plane landed from Jacksonville, Fla., around 2 p.m., the pilot told passengers there was no power at the airport and no gate where they could exit. Around 5 p.m., the pilot said airport officials had started to allow passengers to exit the planes on ladders, Mr. Becker said.
Only five planes could unload passengers at a time, Mr. Becker said, quoting the pilot, and his flight was 26th in line out of 64 planes.
Nearly three hours later, Mr. Becker said he and fellow passengers had made their way off the airplane and were coming to a long line of travelers waiting to get on buses to public transportation and car rental sites.
“It’s one of those things that you hear about but you never think it’s going to happen to you,” he said in a telephone interview.
D. J. Barron, who landed on a plane from Dallas, said the sun had set by the time passengers on his flight were able to exit. “There were the people with glow sticks that had to direct us,” Mr. Barron, 31, said in an interview. “There was no light.”
Airlines canceled more than 1,150 flights into or out of Atlanta, according to FlightAware, the flight data website. That figure accounted for more than 90 percent of the cancellations in the United States as of early Sunday evening.
On a Sunday with clear weather, there are usually fewer than 100 flights canceled across the United States, Sara Orsi, a spokeswoman at FlightAware, said in an email.
Delta Air Lines, the largest carrier at the airport by number of passengers, said on its website that more than 450 of its flights were canceled. A spokesman at Southwest Airlines, the second-largest carrier there, said 70 of its 120 flights out of Atlanta had been canceled, including all departing flights for the rest of the day.
A spokeswoman at American Airlines said 24 departing flights were canceled, as well as 30 arrivals.
Outside of Atlanta, passengers reported delays affecting other airports across the country.
The Federal Aviation Administration said in a statement that its Atlanta tower had electricity and was operating normally but that it had issued a “ground stop,” which meant all flights headed to Atlanta were held at their departure airport.
As the day dragged on, travelers vented on social media about being stranded, the need to make alternate plans and what they complained was a lack of timely information. Some posted photos of passengers standing in the dark in the terminal.
The airport said on Twitter that power had been restored in Terminal F around 7:30 p.m.
William Kimble, 37, was at the Atlanta airport for a layover en route to San Antonio when the power went out. He spent hours in an airport lounge, struggling at times to use the internet with an increasingly spotty data connection.
Despite the lack of information, he said in an interview on Twitter, “passengers here are calm,” adding, “One would assume the folks stuck out on planes are not as happy.”