Pilot Should Have Seen Aeromexico Jet : Odds Were Only 10% That He’d Not Spot DC-9, Expert Says

Pilot William Kramer had a 90% chance of seeing an Aeromexico jet 12 seconds before his small plane collided with the DC-9 over Cerritos on Aug. 31, a collision-avoidance expert told a National Transportation Safety Board hearing Friday.

By contrast, said John Andrews, a staff member of the Massachusetts Institute of Technology’s Lincoln Laboratory, the captain of Aeromexico Flight 498 had a far less favorable angle of view of Kramer’s Piper Cherokee.

The jet’s crew had only a 42% chance of seeing Kramer’s plane 12 seconds before the crash--the minimum time considered necessary for avoiding a collision, said Andrews, who based his calculations on a statistical model culled from 250 near-miss flight tests.

According to eyewitnesses, neither plane took evasive action before the nose wheel of the Piper hit the tail of the jetliner.

The combined chance of both pilots failing to see the other was minimal--only 6%--Andrews said.

Andrews’ testimony, which came as an NTSB board of inquiry completed four days of public hearings in Los Angeles, provided the first quantifiable evidence of which pilot had the better chance of seeing the other before their planes collided at 6,400 feet, killing 82 people.

In one sense, however, the evidence served to only deepen the mystery of Los Angeles’ worst midair collision. For if there was ever a pilot who seemed unlikely to ram into an airliner, it was Kramer.

According to NTSB staff reports prepared for the hearing, Kramer, 53, was described as cautious, meticulous, painstaking and even “old-maidish” by various flight instructors and friends when it came to flight preparation and scanning the skies for other traffic. Initial indications that he suffered a heart attack in flight have been largely discounted.

The contradiction between Kramer’s reputation and his failure to see the jet is one of two key questions that appear to make clear-cut resolution of the Cerritos crash a dim possibility.

This week’s hearings bore out a prediction made a few days after the accident by Dr. John Lauber, the head of the NTSB on-site investigation, who said he did not expect to find a single cause.

After all, Lauber said, “an accident only happens because of a series of failures.”

The failure of Kramer and Aeromexico Capt. Arturo Valdez-Prom to see each other was preceded by the failure of the FAA’s traffic control system to keep the two planes out of each other’s way.

It was air traffic control--specifically, the computer system that converts radar data into symbols on the screens of traffic controllers--that drew the most attention and criticism this week.

Testimony clearly established that radar from the Federal Aviation Administration’s Los Angeles Terminal Radar Approach Control (TRACON), which is responsible for guiding planes over the Los Angeles Basin toward Los Angeles International Airport, picked up the path of Kramer’s plane after it left Torrance Municipal Airport and headed east, straying into Los Angeles International’s Terminal Control Area (TCA).

String of Circles

Computer printouts of radar data show Kramer’s plane, a string of triangles, and Valdez-Prom’s jet, a string of northbound circles, heading toward disaster.

However, numerous witnesses contended that not all of the radar data is properly transmitted to the controller’s screen.

Controller Walter White, who was guiding Flight 498 when it crashed, said flatly that Kramer’s plane never appeared on his screen.

White, 35, a six-year controller with a spotless work record, said controllers occasionally encounter this problem and usually become aware of it only when a pilot radios them to complain that controllers failed to warn him about a nearby plane.

Richard Cox, TRACON’s air traffic manager, said the same thing.

“It is inherent in the system,” he said.

Existing Problem

Lawrence Cuesta, an air traffic manager familiar with the Los Angeles system, said the problem had existed since the early 1970s.

A memo by the FAA technical staff, written in 1973, confirmed that computer data was being lost, meaning that some planes picked up by radar were not being transmitted to the controllers’ consoles.

Some expert testimony clashed with White’s.

Two computer systems analysts at the FAA’s Atlantic City, N.J., technical center said such data losses were rare and that if they occurred, they would last less than 10 seconds, not for the longer stretches of time described by White and other controllers.

Further, if the image of the Piper did appear on White’s screen, an adjustment that the controller made to his console would have made it harder for the controller to see it. Following an informal policy at TRACON, White had turned off a backup decoding system that adds two slashes to the normal triangle symbol used to indicate a general aviation plane like the Piper.

Cluttered Screen

Controllers say they forgo the backup system to avoid having a screen so cluttered with data that it cannot be read.

The weight of the testimony was illustrated Thursday by an incidental remark made by one witness, Barry Jay, general manager of the aviation company where Kramer kept his plane.

Asked if, as a pilot, he believed he was always under the eye of FAA controllers when he flew in Los Angeles, Jay said soberly, “That’s the impression I had until today.”

Representatives of several aviation industry groups that participated in the hearing and were allowed to question witnesses said Friday that they are not sure what probable-cause verdict to expect from the NTSB, which will make findings and recommendations within several months.

Concern Voiced

Spokesmen for the Aircraft Owners and Pilots Assn., which represents small-plane owners; the Professional Airways Systems Specialists, which represents FAA radar technicians, and the Airline Pilots Assn. all said they are concerned by testimony about radar flaws.

Don McClure, chairman of the Airline Pilots Assn.’s accident investigation board, said similar complaints about radar malfunctions have been voiced by pilots in other parts of the country.

Many of the areas in which the safety board seems likely to make recommendations are already being addressed by the FAA in the wake of the Cerritos crash. The FAA has introduced proposals to expand TCAs, increase penalties for pilots who violate airspace restrictions and require more knowledge of local flight restrictions to pass license examinations.

In Los Angeles, the FAA has begun filing TCA violation cases against about 10 pilots a month, compared to only one a month before the crash.

Aging Radar

The FAA is also planning to replace aging radar and computer equipment at the TRACON facility next year and plans to begin equipping airliners with automatic collision-avoidance systems by the 1990s--a program that the NTSB may recommend be implemented more quickly.

Changes in airspace regulation are critical to Los Angeles, which has the world’s highest density of airplane traffic.

A study conducted for the FAA in 1983 by a Virginia consulting firm said that by the year 2000, the Los Angeles Basin’s area of heaviest airplane concentration will grow from .18 planes per square nautical mile to .45.

In testimony Friday, Joseph Fee, the FAA’s manager of airborne collision and data systems, said that any area more dense than .30 planes per square nautical mile “we call an aluminum cloud.”

The study defined the basin’s most dense area as a path from Long Beach to Los Angeles to Van Nuys.

That density complicates the dynamics of seeing an object in the air. Collision specialist Andrews’ testimony underlined the difficulty pilots face at distances that, to laymen, seem vast.

Short Time

In the Cerritos crash, Andrews said it took only 60 seconds for the two planes--the jet descending into Los Angeles International, the Piper rising--to cover the last 4 1/2 miles between them.

Pilot manuals indicate that pilots should routinely scan 60 degrees in both directions, taking about one second for each 10-degree slice of the sky. From the DC-9 captain’s seat, the Piper was about 19 degrees left, but apparently difficult to see because it came from below. From Kramer’s seat, the jet was about 50 degrees right.

If a traffic advisory had been sent to the jet--even one that merely informed the pilot of the plane’s relative position, not its altitude--”there was a very high probability that the crew of Aeromexico would have picked the Piper up,” he said.

In attempting to determine why Kramer flew into the TCA and then failed to see the DC-9, the NTSB may have little more to go on than speculation:

- Did Kramer, who had flown only 5 1/2 hours in Los Angeles after moving here from Seattle, mistake one ground landmark for another and fly unknowingly into the jet-filled Terminal Control Area? Last December, with typical thoroughness, Kramer took an orientation flight with an instructor--not required of newcomers--and studied the TCA.

His cousin, Chris Bush, testified that he and Kramer discussed how to avoid the TCA by staying south of the Artesia Freeway and climbing above 6,000 feet after passing the Orange Freeway.

However, in reference to past suggestions that Kramer had mistaken one freeway for another, Bush said, “If one is new to the Los Angeles area, I think one could confuse freeways.”

- According to NTSB reports, Kramer, 53, was far more careful about his flying than his health. He was described as a sedentary man who smoked 1 1/2 packs of cigarettes and drank a half-dozen cups of coffee each day and had a dangerously high cholesterol level.

After the crash, the Los Angeles County coroner’s office contended that Kramer had suffered a heart attack but admitted that there was no way to tell if the attack had occurred before the crash. An autopsy conducted for the NTSB by the Armed Forces Institute of Pathology found severe hardening of the arteries and extensive closure of portions of the heart but no evidence that a heart attack had occurred.

Not Required

FAA records showed that when Kramer took his last FAA-required medical examination he was given a blood pressure test but was not required to be checked for cholesterol level or other blood tests. Kramer’s private medical records showed that in 1982 he was found to have a risk of heart attack 50% to 100% higher than the average male.

In both commercial and private aviation, pilot heart attacks are considered the greatest medical threat to flight safety, and underlying heart disease is the most common reason for the FAA to deny a pilot’s medical certificate.

Critics of the FAA’s licensing process say the requirements are too lenient.