Hundreds of flights were delayed or diverted Tuesday after a communications failure shut down radar, radio and telephone contact at an air traffic center guiding flights over nine southern states.
There were no reports of near collisions, but controllers had to clear the skies above a broad area around Memphis in a scramble reminiscent of the hours after Sept. 11, according to the Federal Aviation Administration and controllers.
"We heard, 'All controllers to the control room,' and I knew something was wrong," said Ron Carpenter, president of the local controller's union at the Memphis Center. "This was a very major outage. I've been here 18 years and I can't remember something like this happening."
The outage at a nearby Bell South facility knocked out most of the air traffic center's radios, which run through data lines to transmitting equipment, said Federal Aviation Administration spokeswoman Laura Brown. That meant controllers could no longer talk to aircraft in the region, Brown said.
The FAA facility was guiding 220 air-craft when the outage happened at 11:35 a.m. CT, Brown said. So far it's unclear what caused the outage.
It also cut off signals from three of the nine radars in the area, creating zones where controllers could not see aircraft, particularly at low altitudes, Brown said. Phone lines that controllers use to talk to adjoining air traffic facilities also went dead.
Controllers followed contingency plans that turned over control of aircraft to nearby air traffic facilities and immediately began clearing planes from the sky, Brown and Carpenter said.
The failure took out both the agency's primary and backup data links, Brown said. The FAA will review the failure and examine whether it needs additional back-up systems, she said.
The agency has nearly completed an effort begun in 2002 to update data and telecommunications services at its 4,000 facilities across the country.
The FAA did not have figures on how many flights were disrupted, but flights bound for the region were held on the ground for hours. Northwest Airlines, which operates a small hub at Memphis airport, diverted 19 flights and canceled 13 others, spokesman Jim Herlihy said.
The system was repaired by about 2:30 p.m. CT, Brown said.
Carpenter said that controllers were forced to take creative measures to ensure safety at the facility that oversees high-altitude traffic above most of Tennessee, Arkansas and Mississippi, as well as small portions of Kentucky, Illinois, Missouri, Oklahoma, Louisiana and Alabama.
A handful of radios continued to work, so controllers enlisted the help of pilots, who used their radios to alert other aircraft to the outage. Controllers used their own cellphones to contact other air traffic centers to seek help and to alert them to arriving flights, Carpenter said.
Dave O'Malley, the National Air Traffic Controllers Association local president in Indianapolis Center, said controllers there had to essentially double their workload in just a matter of seconds.
"It's the worst feeling you can have as a controller," O'Malley said. "There's not much you can do. When you take that frequency away, you take our main communication away."