Faulty Radar Prompts FAA Inspections

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Faulty Radar Prompts FAA Inspections Problems at 23 Installations Are Linked to Support Stands or Tilt Mechanisms

By Don Phillips Washington Post Staff Writer Monday, March 19, 2001; Page A02

As a cold wind lashed across Long Island on a December night, the main radar for New York's John F. Kennedy Airport cracked loose and fell backward, briefly leaving air traffic controllers out of radar contact with aircraft in the area and later delaying some flights, officials said.

Federal Aviation Administration investigators, concerned by the incident and a similar falling-radar occurence at Boston's Logan Airport last year, inspected all similar radar installations throughout the nation and uncovered 23 cases, including one at Andrews Air Force Base, where there were problems.

The radar under investigation is ASR-9, which is the system that tracks planes at 134 major U.S. airports, including Reagan National, Dulles and Baltimore-Washington, as well as at military facilities. It is the most modern terminal radar available and is used for tracking aircraft for distances out to a little more than 60 miles.

Of the problem radar systems, 17 were found to have the same problem as Boston: Stripped rivets in the support assembly made the radar unstable. Six were found to have the more serious Kennedy problem: The jackscrew assembly that tilts the antenna up or down was stripped.

The ASR-9 radar systems at National, Dulles and BWI did not show any of the problems found at Kennedy or Logan. At Andrews Air Force Base, the FAA found some rivet problems similar to those at Logan, though not as bad. The radar system has been repaired.

The Kennedy incident has prompted the FAA to redesign the tilting mechanism for radars and to revise its radar inspection policies. The agency said it is analyzing whether the failure was caused by inferior materials, poor workmanship, undetected corrosion or some combination of factors.

In the Boston case, there were a number of sheared rivets on the radar, so the antenna base came apart "like a zipper," said James Link, FAA surveillance team leader. Rivets on the 17 defective radar were strengthened and eventually all 134 systems will be reinforced, according to the FAA.

In the April 22 incident at Logan, hundreds of flights had to be canceled until another antenna was flown in from Oklahoma City and installed.

Although the Dec. 17 incident at Kennedy drew no publicity, it apparently delayed dozens of flights the day after the incident. According to FAA statistics, Kennedy suffered 110 delays the day after the incident, all attributed to air traffic equipment delays, presumably the radar.

However, Kennedy airport did not have to slow operations because the New York area has radar installations at Newark and other nearby airports that can give adequate coverage to Kennedy as long as weather remains clear.

Kennedy controllers plugged into the Newark Airport radar just minutes after the radar fell down. FAA officials said no planes were ever in danger. Officials acknowledged that if the weather had turned bad and visibility had deteriorated, the airport would have been shut down until the new radar was installed and operating.

"If the weather hadn't cooperated, the system would have been throttled," said Peter H. Challan, the FAA's deputy associate administrator for air traffic services.

Radar waves travel in a straight line, and the curve of the earth between Newark and Kennedy is enough to prevent the Newark radar from giving complete coverage to the Kennedy runways. Planes landing at Kennedy disappeared from radar 300 feet above the runway, and departing planes were not picked up by radar until about 600 feet above the runway. Controllers must be able to see the airplanes once they disappear from the radar.

Installing the radar was not easy. For almost three days, FAA technicians bundled against the howling wind and worked on a tower far above the ground to erect the new antenna -- a curved metal latticework 36 feet wide and 17 feet tall.

ASR-9 was built by Westinghouse Electric Corp., now part of Northrop Grumman Corp. The design work began two decades ago. The first installation began in 1989 and was completed in 1995. Raytheon Co. now has a contract to produce the next generation of terminal radar, the digital ASR-11.

"The design 20 years ago was the best we knew," the FAA's Link said. "Would we build them the same today? No."

Radar turns constantly in a circle, and it also has a mechanism that can tilt it up or down as it turns. At Kennedy, that mechanism -- a steel jackscrew that turns inside an aluminum block -- failed when the threads on the jackscrew were stripped.

Alan R. Moore, the FAA's director of Airways Facilities, said radars at six other locations were found with worn jackscrews. Those locations have been repaired and strengthened, he said.

The agency also decided to redesign the tilting mechanism using a stainless steel jackscrew, and all ASR-9's are to be refitted, Moore said. Raytheon had been included in discussions about the problem and will use the new design on ASR-11, he said.

Robert D. Long Jr., deputy director of Airway Facilities, said the FAA is also revising its radar inspection policies.

Under the yearly visual exams, inspectors looked for obvious problems, like external signs of corrosion or whether the facility was still waterproof. Instead radar installations will now be turned off and given a lengthy exam that will look for specific signs of failure.

If inspectors had been told to focus on the possibility of a jackscrew failure, they probably would have found the problem, said Moore, but "in a generalized condition of inspection, they probably would not have seen it."

Jim Reinhard, a spokesman for Northrop Grumman, said the company worked "hand-in-hand" with the FAA on the problem, and that the FAA had come up with a good solution.

FAA officials said the government, rather than Northrop Grumman, will pay for all repairs and redesigns. They said the initial cost of the Kennedy repair was "fairly low" -- $30,000 -- but they have no estimate yet on the cost of redesign and installation of new parts.

The total cost of fixing and replacing the Boston radar and strengthening the other 133 radar installations will be at least $22 million, according to the FAA.

http://washingtonpost.com/wp-dyn/nation/A23566-2001Mar18.html

-- Doris (nocents@bellsouth.net), March 20, 2001


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