Backup generator for radar tracking at airport failed

The backup generator for a radar facility at Seattle-Tacoma International Airport failed Friday after losing regular power from the windstorm, and officials kept planes moving by switching control functions to an Auburn center that normally handles more distant air traffic.

The windstorm also snapped off a radar antenna at the Sea-Tac airport control tower.

The switch of air-traffic control functions caused delays as traffic slowed. Controllers put aircraft into holding patterns in the air or held them on the ground at other airports, said Mike Fergus, spokesman for the Federal Aviation Administration (FAA).

"There was no safety degradation," Fergus said. "Delays, yes."

The facility that went out was the Terminal Radar Approach Control (TRACON) facility beside the airport, which ordinarily handles all aircraft approaching or leaving any airport in Puget Sound.

Normally, the control towers at all local airports hand off control of an aircraft to TRACON as soon as it takes off. TRACON handles the traffic until the airplane is out of the busiest airspace in a 40-mile radius around Puget Sound and then hands off to Air Route Traffic Control Center in Auburn. The same hand-off chain in reverse serves incoming aircraft.

Friday, TRACON went to a backup generator when power went out. But the generator quit when a fuel actuator failed, causing the system to roll automatically to an emergency battery-operated power system.

Because that could operate only for a very limited time, FAA managers decided to switch all traffic to the Auburn center.

"We put our alternative traffic plan into effect," Fergus said. "We didn't know when the commercial power was coming back in."

Fergus said air-traffic controllers from TRACON went to Auburn to assist with the operations.

TRACON resumed control at 1:15 p.m. Saturday, Fergus said.

The antenna that snapped off is used to track the location of planes on the ground at the airport and is essential only when bad weather keeps the tower from seeing the ground.

The failure of that system did not cause a major problem over the weekend, said another FAA spokesman Allen Kenitzer. A crane crew was setting up Monday afternoon to replace the antenna, which should be operating again by this morning.

Dominic Gates: 206-464-2963 or dgates@seattletimes.com