Delta fliers faced delays, cancellations and more headaches Wednesday as the Atlanta-based airline struggled with its computer systems for the third straight day.

The company said 317 flights were cancelled by mid-afternoon Wednesday, in addition to the 800 scrapped Tuesday and 1,000 cancelled Monday.

Hundreds of other flights were delayed. In an update issued at 4:30 p.m. ET, the airline said about two-thirds its roughly 3,100 flights to that point in the day had taken off within 30 minutes of scheduled departure time. The airline said it operates roughly 6,000 flights a day at this time of year.

Delta Air Lines said in an earlier statement that it planned to resume "normal operation" by Wednesday afternoon.

"We're in the final hours of bouncing back from the disruption," said Bill Lentsch, Delta's senior vice-president for airport customer service and airline operations, in a posting on the company's website.

Hundreds of thousands of passengers have been stranded overnight throughout the ordeal, many spending the night in airports around the globe. Others were put up in hotels by Delta, including 2,300 in Atlanta alone Tuesday night.

The system the airline uses to check in and board passengers as well as dispatch its planes is still slow, Gil West, Delta's chief operating officer said Tuesday.

The problems started early Monday when, according to a statement by West, critical piece of equipment failed at the airline's headquarters. It caused a loss of power and key systems and equipment did not switch over to backups as designed.

Delta extended a travel-waiver policy to help stranded passengers rearrange their travel plans. It offered refunds and $200 in travel vouchers to people whose flights were cancelled or delayed at least three hours.

Airlines have been packing more people in each plane, so when a major carrier has a technology crash it's harder to find seats for the waylaid. Last month, the average Delta flight was 87 per cent full.