https://www.vice.com/en_us/article/93a4bd/chaos-as-faa-grounds-every-domestic-flight-in-us-due-to-system-outage

The Federal Aviation Authority announced on Wednesday morning that every domestic flight departure in the U.S. was paused due to an overnight system outage. 

According to the agency, the issue affected the Notice to Air Missions (NOTAM) system, which provides airline staff with updates on changes to normal operation status.