2 Jets Nearly Collide on Approach to Boston

March 23, 2007
A collision alert sounded in the cockpit of Delta Flight 1637 at 4:37 p.m. Tuesday after it came too close to a Delta Connection flight operated by Chautauqua Airlines.

BOSTON - A Delta Air Lines jetliner aborted its landing at Logan International Airport this week after nearly colliding with a regional jet over Hingham Bay.

A collision alert sounded in the cockpit of Delta Flight 1637 at 4:37 p.m. Tuesday after it came too close to a Delta Connection flight operated by Chautauqua Airlines, FAA spokesman Jim Peters said.

In a transmission captured on the aviation Web site liveatc.net, the Delta pilot notified the Logan tower of the close call after he aborted the landing.

"Tower, (this is Delta flight) 1637, we're level at 3,000 (feet). That traffic was just about 100 feet below us."

A passenger on the Delta jet, Brian Phillips of Salt Lake City, said the pilot later told passengers the planes had come within 200 to 300 feet of each other. The pilot seemed to blame air traffic controllers for the close call, Phillips said.

"He said, 'We're going to climb back up to 3,000 feet and try (to land) again and try to figure out what's going on with air traffic control,' because they should have told him, (or) something to that effect," Phillips said.

The smaller plane, a 50-passenger Embraer 145 from Buffalo, N.Y., was on its final approach for Runway 32, the new landing strip for regional flights that opened in November after a three-decade court battle.

The Delta flight, a Boeing 757 out of Salt Lake City, was inbound for a landing on the nearly parallel Runway 33L, which is primarily used by large commercial jets.

Both planes were approaching Point Allerton in Hull in northwest winds gusting to 39 mph.

"We had high wind conditions," Peters said. "It appears that the 757 might have been turned to the left, kind of toward Runway 32."

Staggered approaches to the nearly parallel runways are allowed on clear days when pilots can maintain visual contact with other aircraft, Peters said.

Air traffic controllers had notified the Chautauqua pilot to locate the Delta jet and maintain visual separation, and he acknowledged, Peters said. Controllers also notified the Delta pilot of the Chautauqua flight to his rear left, and he acknowledged, Peters said.

Shortly thereafter, the Delta pilot radioed that he was responding to a collision avoidance system alarm, which is triggered by an onboard radar system, and a resolution advisory alert, which orders the pilot to climb or descend to avoid a midair collision.

The Delta flight climbed sharply and circled over Boston Harbor and landed safely. The other jet continued on to its landing on Runway 32.

The incident illustrates the effectiveness of the collision avoidance equipment, which is required on all U.S. commercial flights, a spokesman for the Washington, D.C.-based Air Line Pilots Association International said.

"It's a great system and the pilots performed what we call a normal but rare maneuver to follow the (alarm) guidance" by aborting the landing, spokesman Pete Janhunen said.

No formal investigation is under way, but because of the alert, the Delta pilot will be required to submit a report to the FAA, Peters said. The FAA will then review any changes to air traffic control procedures at Logan, Peters said.

The $100 million, 5,000-foot Runway 14/32 was designed to reduce delays at Logan by siphoning off traffic from smaller aircraft. Until Runway 32, which is used for landings only, began operation in November, Runway 15R/33L had been the airport's lone operational runway in strong northwest winds and was used for both landings and takeoffs simultaneously. That configuration was being used Tuesday afternoon because of the windy conditions, with only landings allowed on the new runway.

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