The FAA report, obtained by The Sun under the Freedom of Information Act, for the first time reports that only quick action by the USAir pilot averted a possible crash 800 feet over Ferndale. Just 50 feet separated the two planes.
"He was already descending," said Paul Turk, a USAir spokesman. "The pilot had to steepen the angle of descent. It might or might not have been noticeable" to passengers.
The incident occurred about one mile northeast of BWI. The USAir Express plane carried about three dozen passengers.
In their report, FAA investigators concluded that the near-collision occurred when the air traffic controller handling the Cessna 172, Clovell Miller, did not notify a colleague of the Cessna's flight path.
The controller was taken off the job temporarily and given remedial training. Mr. Miller -- who cut short an interview yesterday and then did not return several subsequent phone calls -- told the FAA that he had assumed that a colleague whom he had just relieved had made the proper notification, the report says.
He then granted the Cessna's route request, unknowingly putting it in the path of the descending USAir plane.
USAir Express Flight 3949, coming in from Albany, N.Y., "was descending on visual approach to Runway 15 when the pilot saw the other aircraft directly in front of him," the FAA report says. "The pilot pushed the nose over and flew under the other aircraft by about 50 feet and landed without incident."
The controller handling the 37-seat deHavilland-8 USAir plane, Robert A. Reiter, did not know the Cessna was in the area as he directed the commuter plane into BWI.
"Hey tower, do you copy the Cessna here going across the final approach path?" the unidentified USAir pilot radioed to him.
"Negative," Mr. Reiter responded.
"Wow. That was quite close," the pilot said, adding later: "He went right over the top of us . . . apparently nobody was talking to him."
Mr. Turk said the incident demonstrates that pilots "are alert to their environment. They don't depend totally on what they hear. . . . This is an unfortunate error and the FAA looks like they have taken additional steps to train the controllers involved."
The near-collision was the sixth close call between planes flying into or out of BWI in the past two years, according to FAA records. A near-collision is defined as planes flying within 500 feet one another.
No commercial airliner has ever crashed at or near BWI. In December 1992, a cargo plane went down in an Elkridge industrial park, off Route 1, killing the pilot. In 1989, a cargo plane slammed into a Ferndale home, killing an infant inside the house as well as the pilot.
Officials could not say yesterday how many passengers were aboard the USAir flight, which took off from Albany County Airport at 10:20 a.m. and landed in Baltimore at 11:50 a.m. Mr. Turk said the plane was nearly full.
The Cessna is owned by Colonial Pipeline Co., based in Atlanta, which uses such planes to monitor its vast network of underground pipelines. One in Maryland delivers aviation fuel to BWI from Westminster.
Pilots look for dead vegetation, which could indicate leaks, or heavy equipment operating near a line.
The FAA's report says the controller handling the Cessna, Mr. Miller, "was not familiar with the pipeline route."
A Colonial spokesman, Noel Griese, said pilots have been flying the same pattern near BWI since the early 1980s. "Since this operation is and has been fairly routine for many years it will be incorporated in the facility training program," the FAA report says.
Mr. Miller, in his statement to FAA investigators, said he thought that the controller handling the USAir plane knew the Cessna's course and he felt that the Cessna's request "would have little or no impact on arrival operations."
Mr. Miller said that when he realized how close the two planes were, he tried to warn the other controller, but could not because the radio was busy.
He then transferred communications with the Cessna to the controller handling the USAir flight.
Mr. Miller was decertified as a result of the investigation and ordered to undergo eight hours of remedial training in four categories, including airspace separation and radar handoffs, the FAA report says.
The FAA recertified Mr. Miller Jan. 15. "The employee demonstrated the ability to perform relevant operational duties," the report says. The results of a February follow up were not available.
Mr. Miller is scheduled for another test July 10.