What about my flight?

— Check your flight status before heading to the airport.

— Delta said travelers whose flights are cancelled or “significantly delayed” are entitled to a refund.

— Those who had flights booked on Delta on Monday can reschedule their flights for later in the week without paying certain change fees.

— If your flight has been changed or rebooked, Delta said customers’ original boarding passes will work at the gate for their new flights.

— People whose flights were canceled or delayed more than three hours are eligible for a $200 travel voucher.

A computer system meltdown at Delta Air Lines’ Atlanta hub forced hundreds of flight cancellations Monday and put a spotlight on how quickly airline technology failures can cascade into a crisis that disrupts travel across the nation.

“The airlines should plan better. They should have backup systems,” said Jevon Holder, who was among those stacked up at Hartsfield-Jackson International after Delta halted operations in the early morning. “This is too important to fail.”

Operations resumed as systems were restored but by late afternoon Delta had canceled more than 650 flights. FlightStats.com showed nearly 2,500 delays throughout Delta’s system Monday.

Delta did not say if it expects normal operations Tuesday, but such events can have a lingering effect as passengers have to be rebooked and flight crews reassigned.

The airline said it will offer $200 vouchers for future travel to customers whose flights were canceled or delayed more than three hours as a result of the episode.

The problem started with a 2:30 a.m. power outage that wreaked havoc on computer systems at Delta’s Atlanta hub.

Georgia Power said the outage was caused by the failure of a piece of Delta equipment called switch gear, which switches power flows within a system. That affected flight planning and customer tracking systems, and at 5 a.m. the airline declared a “ground stop” halting takeoffs around the world.

In its update late Monday afternoon, Delta said that after the power outage “some critical systems and network equipment didn’t switch over to Delta’s backup systems,” adding that “investigation into the causes is ongoing.”

The shutdown came just as travelers started flowing into Hartsfield-Jackson and other airports. Monday morning is usually busy as business travelers gear up and vacationers return home. Tens of thousands of affected customers struggled to figure out the status of their flights.

Delta’s problem came only weeks after a similar meltdown at Dallas-based Southwest Airlines — the No. 2 carrier in Atlanta behind Delta.

Such incidents show that computer and power systems for huge operations like airlines are “as important, or more important, as our bridges and other physical infrastructure that need to be constantly upgraded and maintained,” said Ramnath Chellappa, an Emory University business professor.

Delta had made major investments in technology upgrades in the late 1990s, but that was followed by hard times, a bankruptcy reorganization and a merger. In recent years, however, the company has enjoyed record profits.

As a side effect of the outage, many affected travelers said they did not get messages or updates from Delta on their flight status.

“I have had zero communications from Delta,” said John Chapman, of Rome, while waiting in Atlanta for a flight to Milwaukee for an energy conference. He wound up booking a flight on Southwest to Chicago and driving from there.

“I understand the power failure,” Chapman said. “But I would have liked to have seen more communications from Delta.”

Flight status lag time

Even as the morning wore on, Delta acknowledged “lag time” in accurate flight status info on its website, from Delta representatives on the phone and in the airport.

Delta released a video message Monday afternoon from CEO Ed Bastian, who apologized for the inconvenience to customers.

“The Delta team is working very, very hard to restore and get these systems back as quickly as possible,” Bastian said. He called it in “all hands-on deck effort.”

Georgia Power spokesman John Kraft said no other businesses or residences were affected. He said Georgia Power crews responded and determined that Georgia Power’s system “seems to be ok, and determined that it apparently was an issue on (Delta) equipment.”

Fitch Ratings, a credit-rating agency, said it expects “investment-grade companies like Delta and Southwest to have the ability to withstand unexpected events like these without harming their credit profiles.” But Fitch noted that outages can be costly due to rebooking expense and overtime, and can generate ill will with passengers.

It also noted: “The heavy reliance on computer reservation systems and the interconnectedness of airline schedules means that even minor outages tend to cause ripple effects that affect the network well beyond the time of the initial outage.”

Refreshments offered

Proof of that could be seen in the snaking lines of passengers at Delta’s check-in area Monday morning. Delta deployed carts to offer refreshments and beverages to customers at gate areas.

Some travelers took the delays in stride.

“It sucks, but what are you gonna do?” said Lori Leszczynski, whose flight home to Milwaukee was delayed. “This is Atlanta, it’s a major hub, I’m sure they have top people working on it.”

A group of students returning from a Catholic summer camp gathered in the airport atrium waiting for flights to their hometowns, and took it as a chance to spend more time with friends.

“It’s a blessing in disguise,” said Danielle Cormier, a student at the University of Louisiana from Lafayette, La. “We got to meet people going to Turkey!”

Lee McMillan, of Dothan, Ala., was headed to Seattle on business. His 10 a.m. departure was delayed until about 4 p.m.

“If it really was a power outage, you would think they have backup systems,” McMillan said. “You would just think they have redundancy.”

Staff photographer John Spink contributed to this article.