Image: Passenges in Las Vegas
Mark J. Terrill  /  AP
Passengers wait through flight delays Tuesday at McCarran Airport in Las Vegas.
updated 9/16/2004 8:40:45 PM ET 2004-09-17T00:40:45

Failure to perform a routine maintenance check caused the shutdown of an air traffic communications system serving a large swath of the West, resulting in several close calls in the skies, the FAA and a union official said Wednesday.

In at least five cases, aircraft in the sky passed dangerously close to each other Tuesday night after the shutdown knocked out radio contact between pilots and air traffic controllers, the union official said.

Two flights “were almost near-mid-air collisions,” said Hamid Ghaffari, local president of the National Air Traffic Controllers Association.

FAA denies near collisions
Federal Aviation Administration spokesman Greg Martin denied that, saying there was never a danger of a mid-air crash. The agency said it was looking into five instances in which planes apparently got too close to each other during the communications blackout.

In a statement, the FAA also said radio contact failed but radar coverage remained fully operational and aircraft were safely handed off to other air traffic control facilities.

The FAA center at Palmdale, north of Los Angeles, hit by the blackout controls airspace for a vast region that encompasses California, Arizona, Nevada and parts of Utah. The shutdown caused a ripple effect throughout the country as planes bound for the Los Angeles region were held on the ground for about three hours.

“A required 30-day maintenance check on the primary radio and voice communications system was not performed,” the agency said. “This system turns off if this check is not performed.”

It said a backup system also failed because it “was not configured properly to ensure its availability in the event of the primary system’s failure.”

The problems could have been avoided if strict FAA procedures had been followed, the agency said.

Controllers claim trauma
Three workers filed injury claims, saying they were traumatized by seeing flights veer toward one another on radar without being able to do anything, he said.

Airport operations were back to normal Wednesday.

During the outage, air traffic controllers could monitor planes on radar but were unable to communicate with them. Pilots had to switch to another radio frequency to communicate with other control centers that took over flights in the region.

“We couldn’t do anything,” Ghaffari said. “We can’t do our job unless there is communication. If there are no communications, you are helpless.”

Under FAA rules, planes must remain at least five miles apart horizontally and 2,000 feet vertically. In at least five cases, that safety bubble was violated, and in two cases planes came within about two miles of each other, Ghaffari said.

On-board safety equipment that includes a collision-avoidance system helped avert disaster, Ghaffari said.

“That was the hero of the night,” he said.

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