A computer glitch shut off radio communications between air traffic controllers and pilots in six Western states for one minute before controllers shifted to a backup system.
Radio communications were silenced in a 200,000-square-mile area including all of Washington state and parts of Oregon, California, Nevada, Montana and Idaho.
Although the Federal Aviation Administration says the problem is fixed, air traffic controllers have triggered a clause in their union contract absolving them from liability for problems linked to communications equipment.
The problem at the regional air traffic control center in Auburn last Friday was announced by the local chapter of the National Air Traffic Controllers Association on Tuesday.
The disclosure followed two more serious air traffic control problems in less than a week. Hourlong system shutdowns at Oakland, Calif., on Aug. 9 and at Miami last Saturday both were attributed to power outages and failed backup systems. At least two near-collisions were reported during the California outage as pilots tried to make their way by sight.
In the Auburn incident, air traffic was light and there were no accidents or near-collisions as a result of the blackout, the FAA and the controllers’ union agree.
A software problem was blamed for the shutdown at 1:35 p.m. Friday of the center’s new, $1.4 billion, computer-driven Voice Switching and Control Center, which has been in operation for just two months.
The controller on duty realized there was a problem, switched to a backup and then switched to the old system, which is still in operation, FAA spokesman Dick Meyer said Wednesday.
The new system was put back on line Sunday, and the FAA will have the software fixed by Friday, Meyer said.
Union leaders opposed going back on the new system Sunday.
“We’d like to know more about the problem and what the fix is before we use the equipment.” said Carl Jensen, president of the controllers’ local.
However, FAA spokesman Mitch Barker on Tuesday said the new system has been determined to be reliable.
The Auburn facility was the first of 21 regional air traffic centers to get the new system, now in place at Salt Lake City and Denver, and in partial use in Atlanta since Tuesday. The new system allows air traffic controllers to talk to pilots and keep their planes safe distances apart.
Generally, controllers are thrilled with the new system, Jensen said Wednesday, but all parties were aware a few bugs could turn up when it was put into operation.
“Friday a glitch showed up - a rather significant one that eliminated all our communications,” he said. “We’re still working on a new system that has the potential for the same type of error.”