I got to visit the Denver TRACON a few years back. They said that they have a triple redundant system for managing it with radar these days. I asked what happened if it all failed, and got the response of, “Well, we get to go home!”
They mentioned that they could try to use the paper strips, but they’d rather close the airspace over get it wrong.
It’s crazy watching the sheer number of aircraft moving around on those screens and then watching the controllers pop between aircraft to talk to them. It’s like watching someone play a realtime strategy game, except that there are planes with real people instead of it just being a game.
