A Federal Aviation Administration inquiry board has blamed an air traffic controller for the near head-on-collision of two speeding jetliners high over North Carolina on Nov. 1, but points to several contributing factors, including computer failure and a communications breakdown.
The report, made available last night, is certain to add heat to a raging controversy between controllers and the FAA.
The controllers are blaming their failing computers for creating more and more unsafe conditions; the FAA, in its official report, concedes that the computer at the air route traffic control center in suburban Leesburg failed, but holds the adequate backup systems were available and that human failure were the primary cause of the highly publicized incident.
It occured about 7 p.m. Nov 1 when the pilot of an Air Florida Boeing 737 turned to the left to avoid a Delta Airlines Lockheed £1011. The planes carried a total of 208 people, and a captain of one of them later reported to the FAA that the planes passed within 200 to 300 feet of each other.
The Delta pilot, who had received permission from air traffic control to descend through the altitude assigned to the Air Florida plane, spotted the other craft and turned on his landing lights to give warning. Then the Air Florida pilot turned.
According to air traffic control radio transcripts released with the report, the Air Florida pilot complained, "That was a little close . . . We had to take a turn to miss him."
It happened, in the bureaucratic language of the FAA, because of "Controller A's failure to radar identify and maintain the identity of Aircraft No. 2 prior to issuing a descent clearance to Aircraft No. 1."
The initial report of the inquiry board stated that the failure of the air traffic control computer contributed to the incident because it changed "a moderate, routine flow of traffic into a complex situation due to the added workload requirements."
Both the chief of the Leesburg facility and the FAA regional headquarters in New York disagreed with listing the computer failure as the primary contributing condition, and shifted that blame to another controller.
What happened, according to the report, was this: The computerized portion of the Leesburg radar failed, forcing the controllers to use their back-up systems, a World War II-era radar screen. The changeover process was complicated by the fact that the -- back-up radar screen would not lock in place for viewing -- a problem that controllers have complained about for at least five years.
Once the back-up screen was locked down, all the airplanes under control had to be reidentified by hand. The computer, when it works, provides identifying data and altitude assignments, among other pieces of information. When the computer is broken, that identifying data must be written in grease pencil on little plastic strips, called "shrimp boats" by controllers. The "shrimp boats" are then pushed across the radar screen as the planes proceed.
The computer remained out for about 7 minutes, then returned to service. All the airplanes in the sector then had to be reidentified to the computer. Both the Delta and the Air Florida planes entered the sector about this time. The Delta flight was entered into the computer; the Air Florida flight was not.
The Air Florida plane was entering Leesburg airspace from airspace controlled by a regional center in Jacksonville, and the Jacksonville computer signaled the Leesburg computer that it wanted to "hand off" the airplanes.
The "hand off" controller in Leesburg "did not accept the handoff or advise the [primary] controller of his action," the report says.
However, there was a radio instruction from the primary controller to the Air Florida plane -- indicating the primary controller was at least aware of its presence even though the plane had not been entered into the computer and its altitude had aparently not been determined by the primary controller.
Then the Delta captain requested permission to descend; it was granted, and the Air Florida captain complained about the near-miss.
"My first knowledge of (the Air Florida plane) was when he called, complaining of traffic . . ." the controller said in his statement, a part of the report.
The controllers' statements, highly technical, nonetheless reflect the fear of which many controllers speak when they talk about their job and its pressures. In one handwritten statement accompanying the report, a controller writes:
"Give us a back-up system that can handle the volume of aircraft we are now working . . . The (old-style radar) was a good back-up six years ago; it now stinks . . ."