The failure of an instrument landing system at Los Angeles International Airport amid dense fog Monday delayed inbound flights up to 90 minutes and cut the number of landings air traffic controllers could handle per hour by more than half, authorities said.
The outage of the automated equipment represents the ninth radar and radio failure involving air traffic control facilities in Southern California since February -- the highest number of problems of their kind reported in the nation, air traffic controllers say.
Instrument landing systems transmit radio signals that guide airplanes during bad weather when visibility is poor. On Monday morning, heavy fog hugged the local coastline, obscuring LAX.
Ian Gregor, a spokesman for the Federal Aviation Administration, said the automated landing system for the airport’s northern runways began experiencing problems with its radio signal about 3 a.m.
When the problem could not be fixed, he said, air traffic control shifted landings to the southern side of LAX about 6 a.m. and halted departures of aircraft bound for LAX from airports about an hour’s flying time from Los Angeles, such as Oakland, San Francisco, San Diego, Las Vegas and Phoenix.
Gregor said that landings at LAX were reduced from 68 to 32 per hour and dozens of aircraft remained on the ground before the fog lifted about 9:40 a.m. and normal flight operations resumed.
The FAA estimated that the arrivals of 63 commercial flights were delayed an average of 37 minutes. Air traffic controllers said there were delays of up to 90 minutes in some cases.
Gregor said the problem at LAX occurred in a part of the system that controls an airplane’s glide slope or angle of descent during landings. He added that technicians were still trying to repair the equipment Monday afternoon.
“This is unusual,” Gregor said. “The equipment is incredibly reliable, but when it does go out, the impact can be obvious and widely felt by the traveling public.”
The FAA estimates that the agency’s air traffic control equipment is in service 99.7% of the time across the nation. But air traffic controllers say they were concerned about the instrument landing system because there have been eight other radio- and radar-related malfunctions since February at airports and the Southern California control center, which guides aircraft through the region’s busy skies.
Those failures, they say, raised safety concerns for pilots, passengers and airports including LAX, Burbank, Van Nuys, John Wayne in Orange County, and San Diego International.
“The number is unprecedented in the history of air traffic control in Southern California,” said Mel Davis, an air traffic controller and local official for the National Air Traffic Control Assn., the controller’s union. “I have been a controller for 22 years. Never in my experience have I seen more than one significant failure a year.”
Though noting that the “union leadership has a well-documented history of exaggeration,” Gregor said the FAA does not dispute whether equipment failures occur, but only whether the number the association cites is unusual.
“We have thousands of pieces of equipment in hundreds of facilities throughout California. It’s quite a stretch to argue that a handful of unrelated incidents at different locations constitutes any kind of pattern,” Gregor said.