Delta Air Lines said it canceled 680 flights Tuesday as it struggled to “normalize” operations for the second day in a row.

A power outage at the airline’s Atlanta headquarters initally forced it to halt departures on Monday. Sporadic departures began about 8:40 a.m. Monday, and arriving flights were not affected.

About 2,400 flights took off on Tuesday, Delta said.

However, cancellations were not the airline’s sole problem, according to FlightAware, an internet tracking service.

By early evening Tuesday, about 942 of Delta’s flights, or about 25 percent, were running late, it said.

That was up from about 20 percent of the flights that were delayed in the early afternoon.

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Eight flights from Kennedy Airport were canceled and 53 delayed, according to FlightAware. The statistics for inbound flights were not immediately available.

Twelve flights from LaGuardia Airport were canceled and 52 delayed. The totals were almost exactly the same for flights headed to LaGuardia, according to FlightAware.

Delta, in a statement, said its leaders were intent on smoothing its passengers’ trips. Monday’s systemwide cancellations affected more than 1,000 flights.

The airline is offering $200 in travel vouchers to any customer whose trip was delayed more than three hours or whose flight was canceled. Later, Delta noted it gave hotel vouchers to several thousand customers, including more than 2,000 on Monday night in Atlanta.

And “Delta sent reservations personnel from the corporate headquarters in Atlanta to help customer service agents process passengers at Hartsfield-Jackson Atlanta International Airport,” it said.

The company pinned the problems Monday, when the 2:30 a.m. power outage occurred, on “some critical systems and network equipment didn’t switch over to Delta’s backup systems.”

Chief Operating Officer Gil West likened the way computer problems have caused lingering delays to the difficulties a bad storm could cause.

“Similar to what happens after a severe weather event, it is not unusual for a global airline to take more than 24 hours to return to full reliability.”

Problems caused by the loss of power are rippling through Delta’s computer systems, causing “instability,” he said.

“For example, we’re seeing slowness in a system that airport customer service agents use to process check-ins, conduct boarding and dispatch aircraft.”

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This has forced Delta agents to use “the original interface we designed for this system while we continue with our resetting efforts,” West said.

“We were able to bring our system back on line and resume flights within a few hours yesterday, but we are still operating in recovery mode,” Delta Senior Vice President Dave Holtz said on the company’s website Tuesday morning.

“We are sorry for what many of our customers have experienced over the past 24 hours, including those who remain at airports and continue waiting on their flights,” he said.

“We are doing everything we can to return our operations to normal reliability, but we do expect additional delays and cancellations,” he said.

People flying Delta on Tuesday were advised to check the status of their flight before leaving for the airport.

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CORRECTION: An earlier version of this story misstated Delta’s flights cancellations on Monday.