Power outage knocks Chicago TV, radio stations off the air
Willis Tower, which was originally known as the Sears Tower, is the tallest building in Chicago and was once the tallest building in the world and U.S. for varying periods of time.
Because of its height, it is an ideal location for broadcast transmitters — and the building also hosts the facilities for numerous other local radio and TV stations.
Other stations’ over the air signals were not affected by the issues May 17.
Stations that were knocked off the air still were able to send a signal to most cable, satellite and streaming providers so subscribers to those services were still able to see the stations; though AT&T subscribers were affected in some cases.
All of the major broadcast affiliates in the Chicago market — Fox owned WFLD, ABC owned WLS and NBC owned WMAQ — have transmitter facilities in Willis, as does Nexstar owned WGN and NBC owned Telemundo affiliate WSNS.
Univision affiliate WGBO is the only major TV station in the market to not have its transmitter atop the Willis Tower — instead using the John Hancock Center.
While it is not immediately clear why only WBBM, WCIU, WTTW and the two radio stations were affected, it is not uncommon for large scale, enterprise grade facilities such as Willis Tower to segment its electrical systems.
Correction: An earlier version of this story listed the incorrect date of the incident.