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,

The United ground stop has been lifted at airports in multiple cities as the airline resolved a technical issue. There are still residual delays.

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.