MIAMI — Atlanta-based Delta Air Lines’ computer system was restored after midnight Sunday, following an outage of over five hours. The airline reported Monday that its operations were recovering, although about 280 flights have been cancelled so far. The airline warned that “a few additional cancellations” are possible.

“I want to apologize to all of our customers who have been impacted by this frustrating situation,” said Delta CEO Ed Bastian. “This type of disruption is not acceptable to the Delta family, which prides itself on reliability and customer service. I also want to thank our employees who are working tirelessly to accommodate our customers.”

The outage is the second for Delta in the last six months after a more widespread, multi-day outage in August 2016 cost the company nearly $100 million. It is also the second outage for a US airline in as many weeks, as United suffered a two hour outage last Sunday, January 22nd.

Delta said customers traveling today should check their flight status. A change fee waiver has been issued for customers scheduled to travel on January 29 and 30, for rebooking by February 3. Delta said unaccompanied minors will not be accepted for flights through noon ET today.