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Aeromexico Crew Unaware of Impending Collision, Tape Indicates

October 30, 1986

WASHINGTON (AP) _ The captain of Aeromexico Flight 498, thinking he was making a routine approach into Los Angeles International Airport, suddenly exclaimed, ″Oh ... this can’t be 3/8″

His DC-9 jetliner had just collided with a single-engine private plane and began careening toward the residential neighborhood 6,568 feet below.

A glimpse inside the cockpit during the final seconds of Flight 498 last August was provided Thursday as the National Transportation Safety Board released the gap-filled transcript of the cockpit voice recorder tape.

Investigators said most of the tape could not be understood because of poor tape quality and excessive background noise.

During much of the time internal conversation, which was in Spanish, was drowned out by the blaring of air traffic communications on an open speaker, officials said.

The tape, however, indicated that neither the captain nor co-pilot was aware of the impending collision over Cerritos, Calif., on Aug. 31 that killed 82 people, including 15 on the ground. There was no sign the pilot had time to take evasive action.

Ironically, as the NTSB documents were released, authorities confirmed that a Boeing 727 jetliner and a helicopter nearly collided Wednesday during the plane’s approach to the Los Angeles airport.

The pilot of United Airlines Flight 282 reported that he had to take evasive action to miss the helicopter, which he said came within 100 feet of him at 2,000 feet 10 miles east of the airport. It was not immediately known what the helicopter was doing in the airspace.

United spokesman Joe Hopkins said the captain ″pulled up and moved over the helicopter and then continued on and made a normal landing.″ He said there were no injuries among the 94 peoiple on board.

According to the documents released by the NTSB on the Aeromexico collision, the final 11 minutes of Flight 498 seemed uneventful as the twin- jet with 64 people aboard made its way north to Los Angeles and prepared for a routine landing.

The co-pilot, Hector Valencia, 26, was believed to be at the controls and the captain had made a routine radio call to the Aeromexico office in Los Angeles for gate information.

A flight attendant entered the cockpit, but her remarks could not be discerned. Then there were apparent gaps in the conversations, all in Spanish, within the cockpit.

As late as 11:51 a.m. and 30 seconds all appeared well aboard the jetliner, according to the transcript, which was released in English with translations of internal cockpit conversations provided by the NTSB.

″Thank you,″ Capt. Arturo Valdes Prom, 46, remarked, but the context could not be established because of the poor quality of the recording.

A few seconds later, the Los Angeles air traffic controller directing Flight 498 told the aircraft to maintain its present speed.

″All right, we’ll maintain one nine zero (190 knots),″ Valdes responded in English at 11:52 a.m.

Ten seconds later, the transcript showed the first and only indication that Flight 498 was in trouble.

″Oh (expletive deleted), this can’t be,″ the captain said. It was the last entry on the transcript and interpreted by investigators as the point where the Piper A-28 apparently slammed into the tail section of the jetliner.

The collision tore loose the critical part of the tail that gives the jet its balance and stability while airborne.

Photographs have shown the DC-9 turning upside down and plummeting nose first toward the ground.

The flight data recorder showed the aircraft’s altitude at 6,568 feet at the time of collision. About 22 seconds later when the transcript shows an end to the tape recording the plane is believed to have slammed into the Cerritos residential area and burst into flames.

The wreckage of the private plane landed in a schoolyard.

The transcript confirmed that the planes collided before the air traffic controller, which was directing the jetliner, became distracted by another private plane that had encroached into restricted airspace.

There had been speculation earlier that the controller might not have noticed the Piper aircraft on his radar screen because of a preoccupation with the other small plane.

The controller has told investigators he never saw the Piper on the screen although investigators said its transponder signal, showing location but not altitude, had been received by the air traffic control computer.

According to the new NTSB documents and Federal Aviation Administration transcripts of air traffic exchanges released earlier in the week, the controller apparently did not shift his focus toward the intruding private plane until about 20 seconds after the collison.

Investigators were disappointed at the poor quality of the cockpit voice recording. A report accompanying the transcript, which covered only the last 11 minutes of the flight, said the tape was ″so severely distorted and noisy that it was difficult (for investigators) to understand the crew’s conversation.″

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