The company has not provided details about the cause of the outage, saying only that Delta's "essential IT systems" went down around 6:30 pm Eastern on Sunday. Thousands of passengers were stranded as carriers struggled to keep older information systems working. Delta did admit to having a systems outage on Sunday night, leading to the cancellation of approximately 150 flights.
A Delta Airlines jet sits on the tarmac at the Atlanta Hartsfield-Jackson International Airport. That's why many airline companies are now trying to use these systems for as long as they can.
The problems come about a week after United Airlines temporarily grounded domestic mainline flights due to an IT issue.
Delta didn't immediately respond to a request for further information on global flights.
On top of that aging system, Gupta added Delta has acquired numerous small airline companies in recent years that all use their own unique systems. The airline said some flights experienced delays upon landing, particularly at Delta's hub airports.
The FAA's Air Traffic Control System Command Center said in a statement that worldwide flights were exempt.
The airline said it "apologizes to customers for the inconvenience".
Delta offered to let passengers booked on flights Monday to delay travel plans for a few days without incurring the usual fee - $200 for domestic flights - for changing a ticket.
The IT systems outage at Delta is the latest of a number that have affected airline operations recently.
Customers planning to travel on Monday are urged to check their flight status at Delta's website or on the Fly Delta mobile app.