Thursday, September 1, 2016

How a deadly 1986 California midair collision ultimately made air travel safer for all



Gary Schank was piloting an airliner from San Francisco to Memphis when he received an urgent warning over the cockpit alert system that his plane was climbing dangerously close to a twin-engine airplane's altitude.

After the system commanded Schank to descend, he guided the plane downward by 500 feet — and a potential midair collision was averted.

"It was resolved quickly," said Schank, an airline captain and practicing attorney who lives in Coto de Caza.

That life-saving technology, known as a traffic collision avoidance system, was introduced in the U.S. in the late 1980s after an Aeroméxico airliner and a small plane collided over Cerritos.

The crash — which 30 years ago today killed 82 people in the air and in the neighborhood where both planes went into the ground — would become a pivotal moment in aviation safety history.




AVOIDANCE SYSTEMS

Blame for the crash was shared equally by the pilot of the smaller plane and the Federal Aviation Administration, a jury found.

Later, the FAA would implement a series of major changes, requiring jetliners to install automatic crash-avoidance systems; mandating the use of transponders operating within certain areas; and consolidating approach spaces for more organized airspace management.

"It highlighted some of the deficiencies that have been corrected ... in areas that technology could help," said George Perry, senior vice president of the Air Safety Institute, part of the Aircraft Owners and Pilots Association.

Prior to those changes, federal investigators concluded that a few minutes before noon on Aug. 31, 1986, the small plane, a single-engine Piper Archer, entered unauthorized airspace and went undetected.

Ultimately, the Piper collided with Aeroméxico Flight 498, which was starting its descent to Los Angeles International Airport after originating in Mexico City. The Piper then crashed into an empty elementary school playground, but the airliner, a DC-9, crashed into a residential neighborhood in Cerritos. Homes were destroyed or damaged, a fire was started, and 15 people on the ground were killed.

"The sights, sounds, smells, the burning material — the destruction made an impression on me," recalled John Lauber, who surveyed the wreckage as a National Transportation Safety Board member.

Lauber, who is now retired in Seattle, says aviation safety standards and protocols have since "come a long way."

The biggest lesson aviation officials drew from the Cerritos crash, he said, was that traffic in high-density airspace in major metro areas had to be more "actively managed."

"I am ... and was a pilot," Lauber said. "So I understand how air traffic control worked and their shortcomings and limits" at the time.

Perhaps the most significant change prompted by the tragedy was the implementation of traffic collision avoidance systems, which were mandated for all jetliners in a 1989 FAA rule.

The system identifies potential midair crashes based on readings of aircraft transponders and instructs pilots to either climb or descend to avert a collision, said FAA spokesman Ian Gregor in an email to the Register.

"It is not an exaggeration to say this has been one of the most important aviation safety improvements in commercial aviation in recent decades," Gregor added.

What's more, following the Cerritos incident, the FAA required all aircraft flying within 30 miles of major airports to have transponders, which wasn't mandated in 1986. The Piper aircraft was not equipped with a transponder that reports altitude and "was not in radio contact with any air traffic control facility when the accident occurred," the federal investigation concluded.

According to Gregor, other major changes included:

Implementing systems that alert air traffic controllers about potential aircraft conflicts.

Establishing dedicated routes for small-plane pilots who want to fly through the busy airspace around major airports.

The consolidation of several approach operations into one facility in San Diego, which makes it easier for air traffic controllers to track all aircraft.

SAFER FLYING

Since the Cerritos tragedy, there has not been another midair crash between a major commercial air carrier and a general-aviation aircraft — thanks to these aviation reforms, some experts say.

The number of all types of midair crashes in U.S. airspace has fallen from 29 to the single digits over the past three decades, according to data from the Aircraft Owners and Pilots Association.

Potential midair collisions — where an incident likely would have occurred had neither pilot taken action — have also dramatically decreased. In 2014, there were a little more than 80 such near-misses reported by pilots — down from 420 the year before the Cerritos crash, according to the U.S. Department of Transportation.

Air safety standards have continued to change over the years with better technology, said Schank, the Orange County pilot.

He recently purchased a device that contains a relatively new technology that allows general-aviation pilots to see other aircraft in the sky, up-to-the-minute weather reports and other important flight information.

The satellite-based technology — called automatic dependent surveillance-broadcast — is similar to the crash avoidance technology available to jetliners but is far more affordable. The key difference is that the satellite-based devices do not provide pilots automated resolution advisories.

The average cost of such a system is $2,000, according to Perry, the Air Safety Institute executive.

The new system wasn't developed specifically to address midair collisions, but it certainly has the "capability to mitigate those" types of situations, Perry added.

By 2020, all aircraft, including airliners and general aircraft, that plan to fly in high-density airspace are supposed to be equipped with this technology, according to an FAA rule.

With the technology, "I can see every airplane in the area," Schank said.

Source:   http://www.eastbaytimes.com

NTSB Identification: DCA86AA041A
The docket is stored on NTSB microfiche number 31249.
Scheduled 14 CFR AERONAVES DE MEXICO, S.A.
Accident occurred Sunday, August 31, 1986 in CERRITOS, CA
Probable Cause Approval Date: 03/07/1988
Aircraft: McDonnell Douglas DC-9-32, registration: XAJED

NTSB Identification: DCA86AA041B
The docket is stored on NTSB microfiche number 31249.
Accident occurred Sunday, August 31, 1986 in CERRITOS, CA
Probable Cause Approval Date: 03/07/1988
Aircraft: PIPER PA-28-181, registration: N4891F

Injuries: 82 Fatal, 8 Minor.

The Safety Board's full report on this investigation is provided as Aviation Accident Report number AAR-87/07. To obtain a copy of this report, or to view the executive summary online, please see the Web site at http://www.ntsb.gov/publictn/publictn.htm 

AT APRX 1140 PDT, A PIPER PA-28, N4891F, DEPARTED TORRANCE, CA ON A VFR FLT TO BIG BEAR, CA. AFTER TAKEOFF, THE PLT TURNED EASTBOUND TWD THE PARADISE VORTAC WITH HIS X-PONDER SQUAWKING 1200. AT THAT TIME, AEROMEXICO FLT 498 (DC-8, MEX REGISTRY XA-JED) WAS ON ARRIIVAL, RCVG NORTHBOUND VECTORS FM LAX APCH CTL (AR-1 CTLR) FOR AN ILS APCH TO THE LAX INTL ARPT. AT 1151:04, THE CTLR ASKED FLT 498 TO RDC SPD TO 190 KTS & DSCND FM 7000' TO 6000'. DRG THIS TIME, THE CTLR WAS CTLG OTR TRAFFIC & PROVIDING RADAR ADVISORIES, BUT DIDN'T SEE A DISPLAY FOR N4891F ON HIS SCOPE. AT 1152:09, N4891F & FLT 498 CONVERGED & COLLIDED AT APRX 6560', THEN FELL TO THE GND. AN INV REVEALED N4891F HAD INADVERTENTLY ENTERED THE LAX TERMINAL CONTROL AREA (TCA) & WASN'T IN RADIO CONTACT WITH ATC. LAX TRACON WASN'T EQUIPPED WITH AN AUTO CONFLICT ALERT SYS & THE ANALOG BEACON RESPONSE FM N4891F'S X-PONDER WASN'T DISPLAYED DUE TO EQUIP CONFIGURATION. N4891F'S PSN WAS DISPLAYED BY AN ALPHANUMERIC TRIANGLE, BUT THE PRIMARY TARGET WASN'T DISPLAYED DUE TO AN ATMOSPHERIC INVERSION.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

RADAR,APPROACH/DEPARTURE..INADEQUATE 
PROCEDURE INADEQUATE..FAA(OTHER/ORGANIZATION) 

Contributing Factors:
IDENTIFICATION OF AIRCRAFT ON RADAR..NOT ATTAINED 
PROCEDURES/DIRECTIVES..NOT FOLLOWED..PILOT IN COMMAND 
UNSAFE/HAZARDOUS CONDITION..INADVERTENT..PILOT IN COMMAND 
VISUAL LOOKOUT..INADEQUATE..PILOT IN COMMAND 
VISUAL LOOKOUT..INADEQUATE..PILOT OF OTHER AIRCRAFT 

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