Power Loss Knocks Out Air Traffic Control Center for an Hour : Safety: Other facilities relay instructions to pilots. Many flights were delayed, but FAA reports no ‘near misses.’

The failure of two backup power generating systems knocked out radar and radio communications at a key Northern California air traffic control center Wednesday morning, leaving airline pilots groping for guidance for more than an hour.

A controller at the center said two jetliners came closer to one another than normal, but the Federal Aviation Administration said it had no confirmed reports of “close calls” or “near misses.”

Carol Long, an FAA spokeswoman in Hawthorne, said most of the 60 to 70 aircraft affected by the blackout switched to alternate radio frequencies at other FAA facilities and were directed into holding patterns until the problem was resolved.

One hundred other planes remained grounded at airports across Northern California, and a ripple effect delayed scores of flights nationwide.

Long said limited radar coverage was restored after about half an hour, with full radar and radio service back on line after about an hour.

The power loss at the Oakland Air Route Traffic Control Center in Fremont occurred when commercial electrical service was cut off for repairs and the center’s two emergency generator systems--designed to kick in automatically in the event of a power loss--failed to activate.

The generator failure was the latest among dozens of air traffic control system breakdowns nationwide in recent months, but the FAA said Wednesday’s incident apparently was unrelated to the other problems, which have been blamed on aging equipment, computer malfunctions and lightning strikes.

The Oakland center handles high-altitude air traffic--keeping planes safely separated as they fly above 10,000 feet over a vast area stretching from San Luis Obispo to the Oregon border and from western Nevada to well off the Pacific Coast.

Other control facilities handling planes as they approach, land at or take off from airfields in the area--including the major airports in San Francisco, Oakland and San Jose--were not affected by the power outage.

The power failure at 7:13 a.m. left pilots without radio communications with the Oakland center. Trained in what procedures to follow in such circumstances, most switched to other frequencies and talked to other air traffic control facilities, some of which have radar coverage that overlaps the center’s. The other facilities--in touch with the center by telephone--relayed holding and routing instructions to the pilots.

“It’s not a terrible crisis when something like that happens,” said Rick Bergholz, a veteran airline pilot. “You revert to procedures in the manual. There are people to call, and you call them and tell them where you are.”

Bergholz said pilots quickly recognize the loss of radio contact.

“There’s almost continuous chatter on those frequencies,” he said. “When you go for five minutes and you don’t hear a sound, you check and see. You figure it out pretty quickly.”

Mike Seko, a controller at the center, told the Associated Press that at least two planes passed one another with less than 1,000 feet of vertical separation or 5,000 feet of horizontal separation during the blackout, but he provided no details. Acceptable separation minimums vary according to a variety of factors.

Bergholz noted that airliners are equipped with on-board collision-avoidance systems that sound alarms if planes get dangerously close together.

FAA spokesman Hank Verbais said there had been an unconfirmed report that a collision-avoidance alarm went off on a plane.

Long said that after the generators at the Oakland center failed to start up automatically, “technicians went in, hooked them up manually and they started.”

At 7:47 a.m., she said, the generators began supplying enough power to give center controllers some radar coverage. She said that at 8:18 a.m., commercial power came back on and complete radar and radio service was restored.