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

United said that the technology issue was not a cyber attack and BWI-Marshall Airport was not among the affected airports listed by the FAA.

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,