https://techcrunch.com/2023/01/11/all-u-s-domestic-flights-grounded-as-key-faa-system-goes-down/

Flights across the U.S. – including potentially all that fly through any domestic U.S. airspace – are delayed this morning as a major system outage means the Federal Aviation Authority (FAA) can’t send out key hazard notices to commercial pilots. The FAA says it’s working to resolve the issue, but the widespread impact continues as of early Wednesday morning.

The agency said at just before 6:30 AM ET on Wednesday that it was “working to restore its Notice to Air Mission Systems” (aka NOTAM) via Twitter – an alert that came after many passengers were already reporting delays to their flights at airports across the country. The Notice to Air Missions System provides key real-time updates about potential flight hazards, as well as any airspace restrictions in place.