U.S. Sen. Barbara Boxer on Thursday demanded that federal officials investigate and fix an equipment malfunction that sparked a two-hour power outage at a regional air traffic control facility earlier this week, leaving controllers briefly unable to see or talk with pilots.
In a letter to Federal Aviation Administrator Marion Blakey, Boxer urged the agency to figure out why a surge-protection system caused backup generators to fail, bringing down all equipment at the Palmdale center Tuesday evening.
"Not only were thousands of travelers stranded, but there could have been a serious accident," the Democratic senator from California wrote. "I am sure you agree that it is crucial for the safety of the flying public that the FAA's backup generators work."
The FAA said it could take technicians weeks to study data from the "equivalent of a black box in an accident investigation."
The box collected information from various systems at the center during the outage.
"We haven't found the cause of it yet," FAA spokeswoman Laura Brown said. After the agency determines what caused the power surge-protection system to fail, it will "look at what we could do to prevent it from happening again," she added.
Backup generators at the center kicked on immediately after a truck downed power lines about 4:20 p.m. Nearly 75 minutes later, radio and radar systems died when a system designed to protect backup generators from power spikes failed.
Power was restored at 7:30 p.m. The agency said no planes came too close to one another during the outage.
The incident snarled air traffic across the country, delaying 348 flights and stranding 25,000 passengers at Los Angeles International Airport alone. Controllers at the Palmdale center direct commercial flights over Southern California and much of Arizona and Nevada as the planes travel at high altitudes between airports.
Controllers lost radio communication with pilots for 15 minutes. Radar scopes were down for two hours.
On Thursday, a union representing technicians who fix FAA equipment said the agency had told workers several years ago not to replace a damaged switch in the backup system to save money.
Earlier in the week, technicians attributed the problem to an order from the FAA two years ago that they remove a switch for cost efficiency.
On Tuesday, one of the three remaining switches protecting the backup system from power surges failed at the Palmdale center, causing the others to go down with it.
The FAA denied it was reducing redundancy in backup systems to save money and said it is investigating what technicians at the Palmdale center were told.
The incident marked the second time in less than two years that problems at the Palmdale center have disrupted air service nationwide.
In September 2004, the facility lost radio communications for nearly three hours after a technician failed to perform required maintenance. Backup generators had also been configured incorrectly, which caused them to fail. The shutdown led to at least five instances in which planes flew too close to one another.
Airport and airline officials will meet Tuesday at LAX to discuss the cause of this week's outage and tally its effects.