Delta Airlines has posted on its company website, Delta News Hub, that flights are returning to normal after a ground stop was lifted late Sunday night.   According to Delta, the airline's essential IT systems, which went down about 6:30 PM. Sunday, were restored a few hours later and all systems were back to normal shortly after midnight ET Monday.

 “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 who prides itself on reliability and customer service. I also want to thank our employees who are working tirelessly to accommodate our customers.”

About 170 were canceled Sunday night and approximately 80 flights scheduled for today have been canceled due to the outage with additional cancellations possible.

Delta has issued travel waivers for flights on January 29 and 30 for rebooking by February 3.  Unaccompanied minors are not being accepted on Delta flights through noon ET on Monday. 

Updates are being  provided on news.delta.com.