The Ultimate Detection Gear--the Pilots’ Eyes

Electronic proximity-warning equipment designed to prevent the sort of tragic midair collision that occurred over Cerritos on Sunday is still in the testing stages, and in the final analysis, avoiding such accidents is still up to the pilots.

That was the consensus of federal officials, air safety experts and pilots as National Transportation Safety Board experts flew here from Washington on Sunday night in an effort to determine the cause of a collision between a light plane and an Aeromexico DC-9 that claimed at least 67 lives.

“The pilots have the primary responsibility,” said Bill Bush, a spokesman with the National Transportation Safety Board in Washington. “They’re supposed to use the ‘see-and-avoid’ concept--make sure they keep their eyes open to avoid other planes in the area.”

Federal Aviation Administration officials said the DC-9 was under FAA control at the time of the collision. The light plane was not.

That means that in the moments before the collision, the Aeromexico pilot was talking on his radio to an air traffic controller preparatory to landing at Los Angeles International Airport on a flight that had originated in Mexico City. The pilot of the light plane was not believed to have been talking to anyone, federal officials said.

The FAA has declined to give further details about the circumstances surrounding the accident, but air safety experts and pilots familiar with LAX landing procedures say the controller should have warned the Aeromexico pilot if control radar showed there was another plane near--or on a collision course--with his.

Reliance on Transponder

But John Galipault, director of the Aviation Safety Institute in Worthington, Ohio, said the controller wouldn’t have been able to relay information about the light plane’s altitude unless the small craft was equipped with a transponder that broadcast such information. As of Sunday evening, it had yet to be determined whether the single-engine Piper had a transponder linked to an encoding altimeter.

And without transponder equipment, Galipault said, the controller might not have seen the light plane at all.

“Controllers’ radar is tuned up to receive targets with transponders,” Galipault said. “It’s quite possible that the echo from the (light plane’s) skin alone might not be terribly visible.”

That means the two pilots might have been dependent on eyesight alone. And if that was the case, it obviously wasn’t enough.

Galipault said concerns over the inadequacy of present systems has led to a search for effective--and affordable--equipment to warn pilots that they are on a collision course with another aircraft.

Two Threat Collision Avoidance Systems, one active, the other passive, are currently being tested, but both are years away from widespread deployment.

The active system currently under study by Piedmont Airlines employs ground radar that analyzes the course and altitude of each plane that it picks up and transmits the information to all other planes utilizing the system. Galipault said the principal problem is a price tag for each unit of between $75,000 and $100,000, well out of the reach of the private plane market.

Transmitter, Computer

The passive system being developed for the Navy employs radar, a transmitter and mini-computer aboard each plane. The transmitter sends out a signal, the on-board radar listens for the echo, and the computer calculates whether a collision is imminent. Again, Galipault said, the price is currently prohibitive for private pilots.

Galipault said the need for effective collision avoidance systems is especially acute over the Los Angeles area.

“One-third of all the air traffic in the United States is over Southern California,” he said. “The FAA has estimated that if you take a given point in Southern California, there probably are 15 planes in the air within a radius of four miles. That’s pretty dense.

“And nobody has resolved the problem of how to keep controlled and uncontrolled airplanes separated.

“Everyone knew there was going to be another collision,” Galipault said. “We were bound to have one. It was just a question of where it was going to be.”