- The Washington Times - Monday, October 22, 2001

LINTHICUM,Md. (AP) For 27 hours in August, the main radar system at Baltimore-Washington International Airport went down and its two backups malfunctioned, BWI air-traffic controllers said.
Controllers said the situation left them blind at times to planes they were trying to guide.
But Federal Aviation Administration officials said conditions were not unsafe at the airport.
Fearing possible aircraft collisions amid the radar problems, BWI controllers said they asked supervisors to temporarily shut down the airport's airspace but were turned down.
Instead, air traffic continued at almost normal levels, and tower managers apparently kept quiet about any problems on Aug. 30-31. They did not notify pilots flying through the airport's airspace who thought the backup radar was working.
About 1,700 planes flew through BWI's airspace during the period, and about 800 of them took off or landed at the airport, controllers said.
There were no collisions or near-collisions. But controllers said there were times when they had to track planes and keep them the required distances apart by jotting notes on paper and using guesswork. They said images of planes disappeared from their radar screens for as much as 20 miles.
Rockton Thurman, a senior BWI controller, estimates that more than 1,000 flights during the period disappeared for unusual lengths of time from controllers' screens.
"Without wanting to sound alarmist, the potential scenario was the worst-case scenario," Mr. Thurman said. "All it would have required was an aircraft not checking in when it was supposed to or misreporting an altitude or anybody not following an instruction or a controller making a mistake. We got lucky."
FAA and Maryland Aviation Administration officials said last week that they had not been notified of problems with the backup radar. An FAA spokesman said Friday that reports indicate the backup system, known as CENRAP, had worked properly and denied that conditions were unsafe.
FAA spokesman Jim Peters would say only that, eventually, the agency was able to restore BWI's main radar system late the second day.
"That's all we're going to say," he said.
The acting executive director of the Maryland Aviation Administration, Beverly Swaim-Staley, called the FAA on Friday after learning for the first time about the problems of Aug. 30-31.
"I've been assured that safety was not compromised during that period," she said.
Radar failure, usually from storms, occurs a couple of times a year at BWI, forcing controllers to depend on backup systems.
At 6:34 p.m. Aug. 30, lightning knocked out the airport's primary radar, known as ASR-9, and its immediate backup system, called CENRAP-Plus.
Departures were halted and arrivals diverted over the next hour while technicians tapped into CENRAP, a less sophisticated backup system.
Controllers began receiving new radar images 16 minutes later but said they immediately met with problems.
Soon after the second backup system kicked in, controllers said, they noticed significant "blind spots." Some aircraft traveled distances as much as 20 miles before being picked up by radar. Other planes that were being tracked suddenly disappeared for the same distances.
Controllers said supervisors rejected suggestions that traffic be stopped until the problems were solved.
Other than increasing the minimum three-mile separation between planes to five miles, a step taken automatically when using the second backup system, little else was done in the way of added safety precautions.
Controllers repeatedly contacted other towers for help in determining the positions of some planes. Fearful of the inability to keep track of flights, they used "paper stops" holding aircraft level at certain altitudes and keeping notes of their whereabouts on paper while they waited for pilots to report their locations.
Tower managers could not be reached or declined to comment on the incident.
Later Aug. 31, when the tower's evening shift began about 2:30 p.m., a traffic-management coordinator began rerouting some aircraft around BWI airspace. Controllers identified the coordinator as Pat McKay. Efforts to reach Mr. McKay were unsuccessful.
The radar problems continued until 9:20 p.m., when repair on the main radar was completed and it went back into service.

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