Delta Air Lines Inc's flights gradually resumed on Monday after an outage hit its computer systems, grounding planes and stranding passengers of one of the world's largest carriers at airports around the globe.
Atlanta-based Delta, the second-largest U.S. carrier by passenger traffic, said it had canceled about 300 flights after a power outage that began around 2:30 a.m. in Atlanta.
The power interruption caused a "system-wide outage," Delta said. At about 10:30 a.m., it said about 800 of its nearly 6,000 scheduled flights had taken off.
Georgia Power said a piece of Delta equipment failed and caused the airline's computer systems to lose power. The problem at Delta did not affect other Georgia Power customers, and there was no area-wide outage, utility spokesman John Kraft said.
Kraft said he did not know the type of equipment that failed or why it did.
Like many large airlines, Delta uses its proprietary computer system for its bookings and operations, and the fact that other airlines appeared unaffected by the outage also pointed to the company's equipment, said independent industry analyst Robert Mann.
Critical computer systems have backups and are tested to ensure high reliability, he said. It was not clear why those systems had not worked to prevent Delta's problems, he said.
"That suggest a communications component or network component could have failed," he said.
A Delta spokeswoman declined to comment when asked about backup systems.
Delta's flight information was not showing correctly on Delta's website or on airport information boards, and this could also take time to resolve, the carrier said in the latest update. Mann said monitors typically display cached data until the computer system updates with new information.
The booking area of Terminal 4 at John F. Kennedy airport was calm Monday around 11 a.m., showing little sign of the computer problems. Several Delta employees said it was much busier hours before, but they had gotten through the rush.
Brandy Lakis, 41, was in New York for a girls weekend and scheduled to fly back to her home in Los Angeles on Monday, but her flight was delayed hours. She quickly rebooked on American Airlines.
"It was so much fun until this morning," Lakis said about the weekend. "It's frustrating, but I have a safe guard because I'm getting home tonight."
Lakis said her original flight was at 1:45 p.m., but when she arrived at JFK, the agents told her it was delayed until 4:30 p.m. She asked for a refund and got one with ease, she said.
Lakis said she was surprised Delta gave a refund for the delay. She had only expected one if the flight was canceled.
"It's par for the course," she said, adding she flies regularly. "I think you have problems on any airline."
Delta said passengers booked for travel Aug. 8-12 would be entitled to a refund if their flight is cancelled or significantly delayed.
According to website Flightradar24, some of the first flights to take off were from Amsterdam to the United States, while a flight from Phoenix to Atlanta was among the first to depart from a U.S. airport.
Delta is a member of the SkyTeam alliance alongside airlines including Air France-KLM. It also partners for transatlantic flights with Virgin Atlantic, which said its flights were operating normally but cautioned that passengers should check tickets in case their flight was due to be operated by Delta as part of a code-share agreement.
Delta's outage follows several high-profile computer problems faced by U.S. airlines in the past year.
Budget carrier Southwest Airlines Co halted departures last month after a technical problem, while American Airlines suspended flights from three of its hubs last September after technical problems.
Industry consultants say airlines face an increasing risk from computer disruptions as they automate more of their operations, distribute boarding passes on smartphones and fit their planes with Wi-Fi.