The FAA facility handing arrivals and departures for Chicago's two main airports shut down earlier today:
The FAA started issuing revised flight departure times to airlines Tuesday afternoon after an approximately two-hour “ground stop’’ halted all flights to and from Chicago’s two airports because of smoke in an air traffic radar facility serving northeastern Illinois, airline officials said.
The ground stop was ordered as FAA workers were evacuated from the radar facility and operations transferred to the FAA's Chicago Center in Aurora, which usually handles just high-altitude traffic.
The smoke was traced to a faulty ventilation motor and the workers were allowed back into the facility around 1 p.m.
No planes were imperiled by the outage. The Chicago Center facility has no trouble handling arrivals for an hour or two.