MIAMI — A major Chicago area air traffic control (ATC) facility was shut down Tuesday afternoon after a bathroom ceiling fan caught fire inside and was evacuated. The incident caused one of the busiest regions of airspace in the world to came to a grinding halt for hours. It is unclear to what extent operations have rebounded.

The facility in question is the Chicago TRACON building, which handles all arrivals and departures to the region. Without it, airplanes are unable to talk with controllers and descend safely to lower altitudes in preparation for landing. Consequently both of Chicago’s major airports, O’Hare and Midway, were placed on an FAA-mandated ground stop until around 3PM local time. Controllers from the affected facility migrated to a nearby facility – Chicago Center – in Aurora, IL, where they were able to resume limited operations. The affected facility, located in Elgin, IL, has reopened, but it is unclear to what extent it has resumed operations.

The outage has meant hundreds of flights and thousands of people were left stuck on Chicago airport runways and taxiways or mulling inside terminals for hours, waiting for what would come next.The latest reports from O’Hare indicate departures have increased to every few minutes, still far above the normal rate of one plane every thirty seconds.

In sum total over 700 flights between the two airports were cancelled as a result of the outage.

Earlier in the day, frustrated pilots lined up with plane fulls of passengers at Chicago O’Hare for what was expected to be an indefinite wait.  Controllers told them they could leave the gate in get in line, but that officials estimated wait times measured in hours before they could “even think” of getting airplanes off the ground. An O’Hare controller summed it up nicely at the time, saying that “The plan of action is nobody’s going anywhere for the forseeable future.”