Computer System Precipitated Japan Jet Crash, Probe Finds

TIMES STAFF WRITER

A terrifying battle between an inexperienced co-pilot and his airplane's super-sophisticated computer system preceded last month's crash of a Taiwanese jetliner that killed 264 people, Japanese investigators said Tuesday.

Trouble for the China Airlines Airbus A300-600R, en route from Taipei to central Japan's Nagoya airport, began about two minutes before it was due to land. At that moment, for unknown reasons--possibly human error, investigators say--the craft went into computer-controlled "go-around" mode, used when a landing attempt is abandoned.

But the 26-year-old co-pilot, who was at the controls, continued to try to land, Manabu Matsumoto, head of the Transport Ministry's accident investigation committee, said at a news conference.

The entire episode, as he outlined it, reflects how increasingly complex technology can seemingly pose challenges to human competence.

In last month's crash, the computer automatically moved the plane's horizontal stabilizer flaps to lift the plane's nose--to gain altitude to circle around for another landing attempt. But the co-pilot kept adjusting the elevator flaps on the rear fin to try to ease the plane down.

The computer compensated for his actions by angling the stabilizer flaps farther in the opposite way.

In just 30 seconds, the pilot warned the co-pilot three times that the plane was in the wrong mode for landing. The co-pilot then canceled the automatic "go-around" mode. But the stabilizer flaps remained set at a sharp angle.

The cockpit crew members at this point realized they were too high to land safely, so they switched the "go-around" mode back on.

As the plane climbed sharply, a stall-prevention system cut in automatically, raising engine thrust to the maximum. But this added to the sharpness of the climb, bringing the plane to an upward angle of 53 degrees, which is closer to vertical than horizontal.

This extremely steep pullup caused a stall; the airplane started to drop.

But the craft recovered forward speed. Then, while it was flying 150 m.p.h. at a height of 260 yards, the entire electrical system stopped functioning for unknown reasons.

The flight data and cockpit voice recorders, on which investigators based their reconstructions, stopped at that moment.

Seconds later, the plane crashed with 271 people on board; seven survived.

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