FAA eyes antenna for radar errors
Logan officials ask FBI to rule out sabotage
Federal aviation officials last night focused on a problem antenna as the possible cause of a malfunctioning radar system slowing flights in and out of Logan International Airport. After two full days of delays, frustrated Logan officials also asked federal investigators to rule out sabotage.
Investigators with the Federal Aviation Administration found errors during tests on the radar antenna atop Logan's control tower, and replaced the equipment last night with a new one from Maine, said spokeswoman Arlene Murray.
The investigators planned to test the replacement overnight. A series of tests yesterday on the rest of the radar equipment at Logan found no problems.
If the antenna is not the cause, then investigators plan to focus on pinpointing an as-yet unknown source of radio interference. Yesterday, a high-technology van drove around the airport trying to track the interference, and could eventually scour the region, which stretches from Nantucket to Portland, Maine, for the source of the interference, which could be anything from a building to a cellphone tower to a ship at sea.
A high-ranking official at the Massachusetts Port Authority, which runs Logan, said yesterday the agency had contacted both the Federal Bureau of Investigation and the Transportation Security Administration to help rule out any malicious intent behind the radar glitch.
''We're just covering all the bases," said the official. ''We've got a critical piece of infrastructure that's down and we don't know why."
The radar system, which transmits an airplane's position and flight information, works by radio waves on a single frequency that are sent out from Logan's control tower, hit a plane, and bounce off a series of radar beacons across New England. The information is distributed to radar screens at Logan and across the region.
When the radio waves are diverted or blocked, the system can generate incorrect data. Another Massport official familiar with the investigation said it is ''very, very, very, very unlikely" that the problem is caused by new buildings at Logan -- three floors atop the central parking garage and the new $400 million Terminal A.
Until the flaw is fixed, Logan's capacity has been slashed in half, with only one runway for takeoffs and another for landings. Yesterday, the airport handled 26 to 28 incoming flights per hour, compared to a normal good-weather maximum of 60. Thousands of passengers faced canceled flights and delays of one to five hours or more for a second consecutive day.
''We are not very happy," said Jessica Hinman, 28, of Grass Valley, Calif., who lost an entire day of her first vacation in Ireland. Her American Airlines flight Monday from San Francisco to Logan was delayed for four hours, then canceled.
''We'll never come to this airport again if we can help it," Hinman said as she waited to get on last night's American flight from Boston to Shannon.
Starting Sunday, radar screens at the Boston Terminal Radar Approach Control in Merrimack, N.H. -- the center that controls commercial airspace up to 14,000 feet in the area from Laconia, N.H., to north of Plymouth, Mass. -- have been showing air traffic controllers ''false targets." Controllers are getting multiple false transponder readings around real aircraft detected by the radar, Massport officials said. The false images set off the system's audible warning against potential collisions, according to FAA officials.
The false readings began Sunday morning, stopped for a few hours, then resumed Monday morning during a weekend of heavy holiday air travel. The problems continued yesterday as a five-member team from the FAA's technical headquarters came to Logan from Atlantic City to troubleshoot the problem.
FAA officials switched to another FAA radar system in Nashua, N.H., on Sunday as a backup. The system is slower than the one at Logan, prompting controllers to increase the space between planes going in and out of Logan from 3 miles to 5 miles. One controller said some distances between planes over the weekend were as great as 8 miles to account for strong tailwinds produced by storms.
Delays of inbound flights averaged 2 hours and 20 minutes yesterday morning, according to Massport officials. The impact varied widely among airlines. At noon,
US Airways Inc. spokesman David Castelveter said his airline had canceled 12 flights out of Boston yesterday, and by late afternoon most flights were delayed no more than one hour.
Dr. Mark Lyons, a Phoenix neurosurgeon who was in town for a seminar, was looking at a five-hour delay on his five-hour flight back home. ''I came here for a day-and-a-half meeting, and it feels like it's going to take that long to get out of your airport," Lyons joked.
Officials at Manchester Airport in New Hampshire and T. F. Green Airport in Warwick, R.I., reported no influx of passengers trying to avoid delays in Boston.
Mike O'Rourke, a retired National Transportation Safety Board investigator who specialized in air traffic control and radar issues, said problems with the radar system have been around for years across the country and can be caused by anything from a billboard to a building. In Minneapolis, O'Rourke said, false targets on local radar screens were detected when the door of an old airport hangar was open, and disappeared when it was closed.
Other aviation specialists have said the radar problems are unusual.
The National Air Traffic Controllers Association, the union representing air traffic controllers that is negotiating a new contract with the FAA, plans a conference call with reporters today on its longstanding safety concerns with equipment malfunctions at regional FAA radar centers.
Union officials said new equipment in the 18-month-old Merrimack center is causing controllers to temporarily lose contact with airplanes. They also said new radar software gives incorrect information for jets that have recently taken off. Controllers said they are often forced to take their eyes off the radar scopes to study written lists of scheduled departures.
''Any time our eyes are distracted from the scopes, safety is compromised," said Andy Blanchard, local representative for the union at the regional radar center in New Hampshire.
He said this malfunction came at ''the worst time" with the heavy rainstorms that swept through the region. Collision alarms were blaring in the center throughout the weekend. ''It's stressful and nerve-racking to the controller," he said. ''And with the weather . . . you don't need false-alarm collisions when you're trying to move a lot of airplanes."
Mac Daniel can be reached at mdaniel@globe.com. Peter J. Howe can be reached at howe@globe.com. Matthew Brelis of the Globe staff contributed to this report. 
