Tens of thousands of Delta passengers around the world were stranded Monday after a power outage at its Atlanta headquarters caused a global computer failure that halted all flights.
Check-in systems, airport screens and even the airline's website and smartphone apps were affected by the meltdown, which began at 2:38 a.m. ET and lasted six hours.
The airline suspended departures, with airport agents writing out boarding passes by hand. "Our systems are down everywhere," it told customers on Twitter.
The outage ended at about 8:30 a.m. ET, with "limited" resumption of flights. Some 427 flights had been canceled, the airline said.
Customers were warned that major delays and cancellations would continue.
Thousands have already spent the night on airport floors. The airline is allowing passengers to rebook for travel as late as Friday to avoid the chaos.