https://www.siliconvalley.com/2023/01/11/faa-glitch-bay-area-airports-see-some-delays-cancellations-after-national-systems-meltdown/

A breakdown in the Federal Aviation Administration’s communications technology led to thousands of delayed or canceled flights throughout the country Wednesday, and the ripple effect was felt by all three major Bay Area airports.

The cause of the outage will be investigated by the federal Department of Transportation, President Joe Biden said. Air travel was halted for hours before resuming just after 6 a.m. Pacific time.