The FAA acknowledges the air traffic control system that handles traffic coming in and out of Newark Liberty International Airport is antiquated. After a recent incident, about a half dozen controllers sought trauma leave due to working conditions. Since April 28, nearly 900 flights have been canceled in and out of the busy airport.
https://www.cbsnews.com/video/what-to-know-about-air-traffic-control-system-staffing-at-newark-airport-amid-delays/