Delta Air still struggles to cope with systems crash on day 2

Travellers on Delta Air Lines endured hundreds more cancelled and delayed flights on Tuesday as the carrier slogged through day two of its recovery from a global computer outage.

By early afternoon, Delta said it had cancelled about 530 flights as it moved planes and crews to "reset" its operation.

Nearly 1,200 Delta flights had been delayed, according to tracking service FlightStats Inc.

"We are still operating in recovery mode," said Dave Holtz, the airline's senior vice president of operations.

Tuesday's disruptions followed about 1,000 cancelations and 2,800 delayed flights on Monday after a power outage at Delta's Atlanta headquarters tripped its booking, communications and other systems.

The airline was back online after a few hours Monday, but the ripple effects could be felt a day later (SEE: Computer glitch at Delta Air Lines grounds passengers worldwide). More than 1,000 people spent the night at Narita Airport outside Tokyo because of the shutdown. While flights resumed in the morning, Delta spokeswoman Hiroko Okada said more delays were expected.

Delta also extended a travel-waiver policy to help stranded passengers rearrange their travel plans.

The airline posted a video apology by CEO Ed Bastian. And it offered refunds and $200 in travel vouchers to people whose flights were cancelled or delayed by at least three hours.

Delta's challenge on Tuesday was to find enough seats on planes during the busy summer vacation season to accommodate the tens of thousands of passengers whose flights were scrubbed.

Airlines have been putting more people in each plane, so when a system of a major carrier crashes, as has happened with others before Delta, finding a new seat for the waylaid becomes more difficult.

Last month, the average Delta flight was 87 per cent full.

Confusion among passengers on Monday was compounded as Delta's flight-status updates crashed as well. Instead of staying home or poolside at a hotel until the airline could fix the mess, many passengers learned about the gridlock only after they reached the airport, where they were stuck.

Delta spokesman Trebor Banstetter said that after the power outage, key systems and network equipment did not switch over to backups. The investigation of the outage is ongoing, but Banstetter said that there is no indication that the problems were caused by a hack or intentional breach of the system.

A spokesman for the local electric company, Georgia Power, said the problem started with a piece of Delta equipment called a switchgear, which direct flows within a power system. No other customers lost power, he said.

Airlines depend on huge, overlapping and complicated systems to operate flights, ticketing, boarding, airport kiosks, websites and mobile phone apps. Even brief outages can now snarl traffic and, as the Delta incident shows, those problems can go global in seconds.

Last month, Southwest Airlines cancelled more than 2,000 flights over four days after an outage that it blamed on a faulty network router. United Airlines and American Airlines both suffered outages last year - United has struggled with several meltdowns since combining technology systems with merger partner Continental Airlines.