Flights were delayed or cancelled across the US on Wednesday, January 11, after a Federal Aviation Administration (FAA) system outage forced the agency to ground domestic flights.The FAA said on Wednesday morning that it was working to restore its Notice to Air Missions System, which alerts pilots to potential flight operations problems, and ordered all US airlines to delay domestic departures until 9 am Eastern Time.“Operations across the National Airspace System are affected,” it said.Flight Aware listed over 4,300 delays and 761 cancellations of US flights.The FAA later said the ground stop was lifted and air traffic was gradually returning to normal.This footage from Greater Rochester International Airport in New York shows people exciting a security area. Credit: Joseph Frascati via Storyful