cfcaviation
FAA Meltdown: NOTAM System Outage Grounds 1,000's
The FAA's Notice to Air Missions (NOTAM) system suffered a nationwide outage, grounding thousands of flights early Wednesday, Jan. 11, forcing the FAA to issue a nationwide ground stop. Over 4,000 flights were affected, with 1,500 of those being Southwest flights. Around 750 total flights were cancelled as well. The ground stop started around 7:15am Wednesday, with the restriction being lifted just shy of 9am. The DOT will investigate the outage.

Photo source: https://www.cnn.com/us/live-news/faa-system-outage-us-flight-disruptions/index.html
Article sources: https://news.yahoo.com/flight-delays-us-faa-computer-113804140.html?guccounter=1, https://www.nbcnews.com/news/us-news/us-flights-grounded-faa-outage-rcna65243