Collision in the "Birdcage"

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Private Pilot Jim Campbell, flying at 1,500 ft. near Los Angeles, could not believe his eyes. Looking up, he saw a flash of light 1 1/2 miles off to the left of his aircraft. The fireball turned into a plume of black smoke, and Campbell watched in horror as a huge DC-9 airliner dropped its nose and rolled to its left. Twisting upside down, the wounded aircraft picked up speed as it plunged toward earth. "Oh!" shouted Campbell to himself. "Pull her up. Pull her up. Oh, pull her up!"

In the cockpit of Aeromexico Flight 498, Pilot Arturo Valdes Prom was helpless. Glistening behind him in the noonday sun were the falling remains of his plane's horizontal stabilizer, a part of the tail that is vital to maintaining control. Also fluttering to the ground was the fuselage of a single-engine Piper Cherokee Archer that had collided with the DC-9 on the virtually cloudless day. Trying to slow the dive of his 60-ton plane, Valdes threw its two engines into reverse thrust. The whine of the jets grew to an awful roar before the airliner smashed with a fiery explosion into a pleasant middle-class neighborhood of suburban Cerritos, where residents had been enjoying the Labor Day weekend.

All the Aeromexico airliner's 64 occupants perished. So did William Kramer, 53, a retired executive of Kaiser Aluminum & Chemical Corp., who was piloting the Piper; his wife Kathleen, 51; and daughter Caroline, 27. The tragedy was compounded by the devastation on the ground. The disintegrating jet slammed into the tidy houses below, igniting fires and spewing debris over several blocks. Sixteen houses were badly damaged, eight destroyed. The task of counting fatalities turned into a macabre chore as authorities tried to distinguish body parts of the air travelers from those of victims on the ground. The best estimate was that 15 neighborhood people had died, raising the death toll to 82.

The Aeromexico disaster was frighteningly similar to the collision of a Pacific Southwest Airlines jet and a small plane over San Diego on Sept. 25, 1978, which killed 144 people. The latest crash was a harrowing reminder that too little has been done in the intervening years to reduce the danger of small planes straying into the path of big passenger carriers at the nation's increasingly crowded airports. The problem is particularly acute in Southern California, which has the heaviest air traffic of any area in the world.

The danger is not solely the fault of the little planes: in the San Diego crash, federal investigators blamed the P.S.A. crew for failing to keep the smaller craft in view. Still, the scary mix of traffic over a center like Los Angeles International Airport (LAX) may be even more hazardous than it was eight years ago. Says one 747 captain: "You get below 10,000 ft., and it becomes almost suicidal not to devote a tremendous amount of attention outside the cockpit. I can't tell you how difficult it is to pick up a small airplane."

Most small-craft pilots shun the "birdcages" around major airports whenever possible. William Kramer had no such choice: he took off from Torrance Municipal Airport, just ten miles from LAX, and was heading across the city toward Big Bear Lake, a resort area some 90 miles to the east. Kramer, who had moved from Spokane to the affluent Palos Verdes Peninsula early this year, had been licensed to fly for six years but had logged only 231 hours in the air, most of them in Washington's relatively uncrowded skies. On the fateful Sunday morning, Kramer reportedly bought an up-to-date map of the terminal control area that surrounds LAX. In effect at all major airports, the TCA, often described as an upside-down wedding cake, is a restricted area; planes must receive permission from an air controller to enter it. The unusually complex Los Angeles TCA has a uniform ceiling of 7,000 ft., but its twelve sectors have varying floors that grow lower as planes get closer to LAX. The Torrance airport lies under this TCA, at a point where the floor is set at 5,000 ft.

At 11:40 a.m., Kramer, his wife and daughter took off to the northwest toward the Pacific in the four-seat Piper that he had purchased three years ago for $33,000. He then banked to the right and headed eastward toward Big Bear Lake. At that point he was in a sector far enough from LAX to avoid the controlled space if he kept his plane below 6,000 ft. Tragically, he did not do so.

As noon approached, Valdes was guiding Flight 498 toward a landing in Los Angeles. A 14-year Aeromexico veteran, he had departed from Mexico City and made stops in Guadalajara, Loreto and Tijuana. At 11:51, he made his first radio contact with the terminal radar control (TRACON) center at the Los Angeles airport.

Despite the holiday weekend, the air traffic around LAX was not unusually heavy. The unidentified experienced controller covering Flight 498 had only ten radar transponder blips to track on his screen. "It was busy, but we weren't to the point of saturation," said Air Controller Karl Grundmann, another of the men on duty. Flight 498's controller told the pilot to descend from 7,000 ft. to 6,000. At 11:53, he issued a warning to the Aeromexico jet: "Traffic 10 o'clock (slightly to the airliner's left), one mile northbound, altitude unknown." Re- sponded 498: "Roger." This plane is not believed to have been Kramer's Piper. Seconds later the controller's attention was diverted by a "pop-up," a small plane that unexpectedly radioed for traffic advice and instrument control. The controller assigned the plane a transponder code for identification as the craft flew across the Los Angeles Basin. But precious time was wasted when the pilot got the number wrong and had to be corrected.

When the controller turned his attention back to Flight 498, seconds after 11:55, he was shocked to discover that it had vanished from his screen. Frantically he called Flight 498 eight times. There was no reply.

"He was hoping against hope that a transponder had gone out or there was something wrong with the radar -- anything but a crash," recalled Grundmann. "He was looking anguished. We knew something was wrong."

The controller asked another airliner to look for the Aeromexico jet. "I don't see a DC-9," this pilot reported. "But I sure see a lot of smoke." It was coming from the carnage on the ground.

Federal investigators discovered that the Piper's path toward the airliner had been visible on the TRACON screen "for several minutes," as one described it. The planes had collided at 6,500 ft., just 500 ft. above the floor of the protected space. The left wing of the Piper clipped the descending airliner's left side at the tail. The jet's stabilizer sheared off the Piper's top, decapitating Kramer and his two passengers. There was no answer to the crucial question: Why had no one in either plane spotted the other craft in time?

, The investigators speculated that Kramer had made two critical mistakes: he had not sought permission by radio to enter the restricted area; and although his radar transponder was on, as required, it was not equipped to transmit the mandatory altitude information. John Lauber, heading the investigation for the National Transportation Safety Board, reported that the controller said he did not recall seeing the Piper's blip. Even if he had seen it, said Lauber, "if he doesn't have altitude information, then it's a reasonable assumption for him that the aircraft is not operating in the terminal control area."

But many pilots sympathize with Kramer, who had to take off directly under a TCA and was new to the area. Said Art Patstone, an air-show pilot from Ann Arbor, Mich.: "There's no sign in the sky that says, STOP, YOU'RE ENTERING A TCA."

What should be done to prevent yet another San Diego or Los Angeles midair tragedy? Experts in all segments of aviation contend that the Federal Aviation Administration has moved much too slowly in developing airborne electronic devices, already used by some military jets, that could warn an airline pilot when he is dangerously close to another plane and flash directions for avoiding it.

The FAA insists that technical reasons are to blame for the snail-paced progress. But the bigger obstacle may be political. Some $8 billion has accumulated in an aviation trust fund dedicated to improving air safety; the money has been piling up from an 8% tax on every airline passenger's ticket. Many in the aviation industry contend that Transportation Secretary Elizabeth Dole, who is FAA Administrator Donald Engen's boss, has been cowed by the White House Office of Management and Budget into holding these assigned funds in reserve against the federal deficit. "Hogwash!" says OMB Director James Miller III. "If I had a bias, it would be toward air safety." Unfortunately, that bias has yet to be translated into equipment that might make the nation's crowded "birdcages" safer.