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

The airline’s travel alert page notes that a technology disruption may impact flights to or from 14 airports including Newark, Washington, Los Angeles and Chicago.

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,