A tech outage led United Airlines to ground flights nationwide Wednesday night, and even with the issue now resolved, over 1,000 flights have been delayed and dozens canceled.

United Airlines has grounded flights nationwide on Wednesday night due to an issue with its weight and balance computer system.

United Airlines flight schedules are gradually returning to normal after a nationwide technical issue forced flight cancellations and delays Wednesday night. Residual delays and cancellations continued Thursday morning for United Airlines flyers at Chicago’s O’Hare International Airport after one of the airline’s computer systems went down Wednesday night,