(WTXF/AP) - Delta Air Lines canceled about 300 hundred flights Monday after its computer systems crashed, stranding thousands of passengers on a busy travel day.
The flight tracking site FlightStats Inc. said more than 1,000 flights were delayed.
About six hours into the outage, just before 9am ET Monday, the airline said limited flights had resumed but that there were ongoing delays and cancelations.
Many passengers were frustrated that they received no notice of the problems, discovering that they were stranded only after making it through security and seeing other passengers sleeping on the floor.
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This is a statement from the airline: "A Delta ground stop has been lifted and limited departures are resuming following a power outage in Atlanta that impacted Delta computer systems and operations worldwide. Cancellations and delays continue.
It was unclear if the airline was even able to communicate due to its technical issues, and Delta said that there may be a lag issuing accurate flight status on the company website because of the outage.
A power outage at an Atlanta facility early Monday initiated a cascading meltdown, according to the airline, which is also based in Atlanta.
Flights that were already in the air when the outage occurred continued to their destinations, but flights on the ground remained there. Over the next several hours, only a handful of flights took off instead of the hundreds that is more typical for a Monday morning, according to flight-tracking services.
"Delta has experienced a computer outage that has affected flights scheduled for this morning," the Atlanta-based company tweeted to customers affected by delays. "Flights awaiting departure are currently delayed. Flights enroute are operating normally. We appreciate your patience."
The company said its IT systems were down "everywhere" and "hopefully it won't be much longer."
Several applications were affected, including the company's website.
MORE VIDEO: Click here to see slow start, monitors saying on-time at PHL
MORE COVERAGE: Click here for the scene at Delta's Atlanta hub.
At Philadelphia International Airport, FOX 29's Lauren Johnson reported from the Delta terminal on Monday morning. She found a relatively short line in the terminal, but said that may not be the case at the gates.
At the terminal, some passengers were able to check-in and even check their bags. Those passengers may have been able to do so because of their destination. Still, there are no flights leaving, despite TV monitors saying flights were on time.
FOX 29's Bob Kelly suggests departing passengers on all airlines check in as soon as possible. That's because Delta passengers who are not able to fly will try to take unconfirmed seats on other airlines.
American Airlines is PHL's largest carrier. Other cities are in worse situations because Delta is their major carrier.
Airlines depend on huge, overlapping and complicated technology systems to operate flights, schedule crews and run ticketing, boarding, airport kiosks, websites and mobile phone apps. Even brief outages can snarl traffic and cause long delays.
A spokesman for Georgia Power told The Associated Press that the company believes failure of Delta equipment caused the airline's power outage. He said no other customers lost power.
A Delta spokesman said he had no information on the report.
In Richmond, Virginia, Delta gate agents wrote out boarding passes by hand. In Tokyo, a dot-matrix printer was resurrected to keep track of passengers on a flight to Shanghai.
Technology that appeared to be working was sometimes giving inaccurate information. Flight-status systems, including airport screens, incorrectly showed flights on time, something the company said it was trying to fix.
"Not only are their flights delayed, but in the case of Delta the website and other places are all saying that the flights are on time because the airline has been so crippled from a technical standpoint," said Daniel Baker, CEO of tracking service FlightAware.com.
Delta issued an apology to customers and said teams were attempting to fix the problem as quickly as possible.
Many passengers, like Bryan Kopsick, 20, from Richmond, were shocked that computer glitches could cause such turmoil.
"It does feel like the old days," Kopsick said. "Maybe they will let us smoke on the plane, and give us five-star meals in-flight too! "
In Las Vegas, stranded passengers were sleeping on the floor, covered in red blankets. When boarding finally began for a Minneapolis flight -- the first to take off -- a Delta worker told people find friends who had wandered away from the gate area, or who might be sleeping off the delays.
Also among those affected by the Delta situation is Stephen Smith, 32, of Baton Rouge, Louisiana. He has been stuck on the ground for about three hours at Tokyo's Narita Airport on a flight that was supposed to go to Shanghai.
Smith took solace in the fact the air conditioning on the plane was working and said it seemed everyone on board was fine.
"Waiting game at this point," he tweeted to The Associated Press.
Early confirmation of the troubles first came in an official account that responds to customers via Twitter. The company had said its IT systems were down "everywhere." Several applications were affected, including the company's website.
Among those affected was Tanzie Bodeen, 22, a software company intern from Beaverton, Oregon. She left home at 4am to catch a flight from Minneapolis and learned about the delays only when she reached the airport and saw news crews gathered at the door.
Bodeen said that passengers were taking the matter in stride. "It doesn't seem really hostile yet," she said.
Airline data company Flightaware said there were at least 858 cancellations and 7,359 delays across the global industry on Monday morning. It's unclear how many are related to Delta's problems and whether Delta's groundings are reflected in the numbers.
The company said travelers will be entitled to a refund if the flight is canceled or significantly delayed. Travelers on some routes can also make a one-time change to the ticket free of charge.
Computer outages are a periodic plague for airlines. Last month, Southwest Airlines canceled more than 2,000 flights over several days after an outage that it blamed on a faulty network router. Unions called for the airline to replace the CEO, but the board gave him a vote of confidence.
Investors shrugged off Delta's IT mishap. In morning trading, shares of Delta Air Lines Inc. rose 43 cents, to $38.10.