This afternoon at the Jacksonville Air Route Traffic Control Center, one of 22 such centers that oversee U.S. airspace, most of the radar system went down for nearly an hour, along with half of the radio frequencies on which controllers talk to pilots. Landline phone communications at the center, which controllers use to share information with controllers at other centers, failed also. It's not clear if controllers used cell phones to try to deal with the situation as they did when a similar incident happened in Memphis in September.) Officially, cell phones are not allowed in the work area of FAA centers.
The FAA ordered a ground stop on Jacksonville Center, that meant that aircraft around the country planning to cross Jacksonville's airspace had to sit on the tarmac. Jacksonville is the seventh busiest en route center in the United States, handling airspace bounded roughly by the Florida-Alabama border, Orlando, southern Georgia, and the North Carolina-South Carolina border.
No cause for the failures has been announced. This looks like just one more symptom of an air traffic control system that has fallen behind the technological curve and, perhaps, is reaching its breaking point.