Testifies in Collision Over Cerritos : No Blip From Small Plane--Controller

The air traffic controller who was guiding an Aeromexico jet toward Los Angeles International Airport Aug. 31 said Tuesday that his radar screen never showed the presence of the small plane that collided with the jet, killing 82 people, including 15 on the ground in Cerritos.

“The aircraft was positively not displayed on my radarscope,” said Walter R. White, testifying in Los Angeles on the first day of a week of National Transportation Safety Board hearings into the crash.

White, making his first public comments about his handling of Aeromexico Flight 498 and its collision with a small Piper airplane, said that because of the unpredictability of the Federal Aviation Administration’s radar system it is not unusual for him to not spot airplanes.

On the day of the crash, White was tracking and advising the Aeromexico DC-9 on its approach from the Los Angeles Terminal Radar Approach Control facility. Trained in several controller positions, he was on that day assigned to guide jets through a large area east of Los Angeles.

White, 35, a six-year FAA controller with a good work record, said air traffic on the day of the crash was light. In response to questions by the NTSB board of inquiry and representatives of several aviation industry organizations, he discounted any possibility that he had somehow failed to see the image of the Piper on his screen.

His assertion focused attention on the reliability of the radar systems that controllers use to guide planes in and out of the crowded Los Angeles Basin. Critics of the FAA, including some controllers and radar specialists, have said the equipment is outdated.

With NTSB Chairman James E. Burnett Jr. presiding, the investigators intend to examine not merely the technical causes of the crash but the safety of aviation in the Los Angeles area as well. Witnesses have been scheduled to testify on such things as airspace restrictions, traffic control procedures and possible new limits on general aviation.

However, Burnett said Tuesday that no conclusions about the cause of the accident nor recommendations for changing procedures will be announced when the hearings end.

“Neither I nor any other board personnel will attempt to analyze the facts or announce a probable cause at the close of the hearing,” Burnett said. “Such analysis and cause determination will be made by the full safety board after due consideration of all of the evidence.”

As a result, representatives of some segments of the aviation industry are carefully watching the hearing, aware that any factors deemed to be contributing causes will likely be targets for further regulation.

The crash, the worst mid-air disaster in Los Angeles, occurred shortly before noon when the Mexican jet, descending from the south, collided with the Piper, flown by pilot William K. Kramer, who had taken off from Torrance Municipal Airport en route to Big Bear. Kramer had flown into the Los Angeles Terminal Control Area without authorization--far afield of what was believed to be his intended route.

The Terminal Control Area surrounds the L.A. airport and is primarily intended to protect airliners, but with proper equipment and air traffic control approval, any plane may enter it.

Normally, a plane with the equipment that Kramer was using would show up on White’s radar screen as a plane with a distinct location but no discernible altitude because Kramer’s plane did not have an encoding altimeter.

Even so, that crude warning would allow a controller to tell airliners to be on the lookout for a plane in the general vicinity.

White said the radar system he uses is not completely reliable, sometimes because of apparent defects in the system itself, other times when variables such as weather or the direction, type and speed of the aircraft affect the strength of the radar signal.

“I have experienced having not had targets displayed that aircraft have seen and asked me about,” he said. Southern California pilots who fly under “instrument flight rules” have echoed similar complaints, referring to being surprised by nearby airplanes that the controller never saw.

Sometimes a “missing” plane will appear soon after such inquiries, White said. “Other times I will never see it on my scope.

Called Imperfect

“Generally the equipment is adequate . . . but unfortunately radar is not a perfect system,” he said, adding that pilots must continue to rely on the traditional see-and-be-seen concept even when they are under radar control.

White said he knew of other controllers who experienced similar radar problems and said such trouble is normally reported to supervisors, who can attempt to resolve the problem by switching radar channels or systems.

He said that during the six months before the crash, he had asked at least once for a change in channel and had asked at least once to be switched to another system.

On the day of the crash, White said, he “was receiving an adequate radar presentation” on his 22-inch-wide radar screen, which shows air traffic over an area of 50 miles, about half of which White was responsible for in the job he held that day.

His radar screen showed no other planes that might endanger the Mexican jet, White said.

White’s remarks illustrated one contradiction in air control in Los Angeles.

On the day of the crash, he said, traffic was light enough to allow him to scan an area within 10 miles of the Mexican jet for possible conflict, he said.

However, he noted that on heavy days controllers are able to pay scarce attention to intruding small planes. In fact, he said, drawing surprise from one of his questioners, NTSB traffic control specialist Allen Lebo, it is common for controllers to change the coding of their radar systems to, in effect, make themselves less aware of other traffic so that they may focus attention more sharply on dense jet traffic .

In an effort to test White’s contention that he had never seen the Piper, Lebo showed White a computer-generated printout that plotted the colliding courses of the two planes.

The diagram was based on information collected by FAA computers from radar. However, NTSB officials acknowledged that not every piece of that radar data is transmitted to the controller’s screen.

Asked by one questioner if he would like better equipment, White said he would, but added, “That’s a matter for the taxpayers and the Congress to decide.”

It was not until several minutes after the two planes collided--with neither pilot having seen the other, according to the majority of 15 eyewitnesses interviewed by the NTSB--that controllers figured out what had happened. Ironically, during the seconds when the two planes were colliding, White’s attention was focused on another potential problem.

He was talking by radio to another private plane that allegedly had strayed into the Terminal Control Area. (The FAA now plans to suspend for six months the license of the pilot, Roland Furman of Buena Park.)

As White finished his conversation with Furman, he turned his attention back to the Mexican jet, which he was going to direct to a different runway.

“I noticed . . . that Aeromexico 498 was in coast status,” he said, referring to a situation in which a block of data disappears from the controller’s screen. “Shortly thereafter I lost the primary target. . . . I asked Aeromexico to turn left . . . I received no acknowledgement.”