READ HERE: “Normal air traffic operations are resuming gradually across the US following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted,” FAA tweeted. But, grounding all domestic flights for hours has sparked travel chaos this morning. There are currently 4,000 delays within, into, or out of the US, flight tracking website FlightAware showed. Another 700 were canceled.