Delta canceled another 530 flights by Tuesday afternoon as it continues to recover from a monstrous system outage Monday that saw 1,000 flights canceled and tens of thousands of passengers stranded.
More than 200 other flights would likely be delayed throughout the day, the airline warned Tuesday morning.
It came as stranded passengers were still feeling the sting from the massive shutdown Delta said was caused by a power outage at its Atlanta base that crippled computer systems.
"Following the power loss, some critical systems and network equipment didn't switch over to Delta's backup systems," the airline said in a statement. "Delta's investigation into the causes is ongoing."
The utility company that delivers electricity to Delta disputed the airline's explanation. In a statement, Georgia Power spokesman John Kraft said that a piece of electrical equipment "on their (Delta's) system" was to blame for the outage.
"Our crews responded to the site this morning and we continue to work with the team at Delta," the statement said. "Other Georgia Power customers were not affected by the issue with Delta's equipment."
Delta said systems were fully operational late Monday but that residual delays and cancellations continued.
The airline urged passengers with travel scheduled for the morning to check the status of their flights on Delta's website or mobile app.
Delta said it was extending its offer of a refund to passengers traveling Tuesday and was also offering a $200 voucher to passengers whose flights were canceled or who were delayed for more than three hours.