Air traffic controller Ray Smid watched the yellow blips slide across his radar screen. The circles moved in silence, but Smid never forgot that they embodied real aircraft. It didn't matter if the traffic was big or small. Lives were lost if the blips merged.
The eraser-shaped images toted "data blocks" displaying flight number, destination, speed, and altitude. Aircraft climbed and descended; others were at cruise altitude. Smid's flat-panel display constantly changed. The traffic never stopped.
It was 5:20 a.m. on Sept. 26, 2014, and while Smid couldn't see the sunrise from the dim control room at the Chicago Air Route Traffic Control Center (ARTCC), blue sky waited at the end of his shift. Smid had been a controller at the Aurora, Ill., facility for the past 27 years. Unlike airport control towers, Chicago Center and its counterparts in places like Minneapolis and Indianapolis are housed in nondescript buildings far from runways and taxiways.