The FlightAware Misery Map was at its worst at about 1:45 PM with 144 delays reported and 55 cancellations reported at O'Hare.
A ground stop was in effect from the time of the smoke investigation until about 3:17 p.m. A ground stop means that no flights are departing from O'Hare and no flights bound for Chicago O'Hare or Midway are taking off. Same situation for Midway.
FAA workers were evacuated and were allowed to return to the building at 12:50 p.m.
At 1:45 PM
Chicago O'Hare Intl (KORD)
all inbound flights being held at their origin until tuesday at 02:00p CDT (this time ended up being about 3:17 p.m.)
• departure delays an average of 1 hours 3 minutes
• arrival delays for airborne aircraft an average of 30 minutes
FLIGHT DELAYS: SMOKE INVESTIGATION FINDS FAULTY VENTILATION MOTOR AT CHICAGO TRACON http://t.co/JdJsKTHOeC pic.twitter.com/LGkOIagsRC
— ChicagoFireMap (@ChicagoFireMap) May 13, 2014