‘Abnormal Impact’ Cited in JAL Inquiry

An “abnormal impact” aboard a Japan Air Lines jumbo jet triggered mechanical failures that caused the worst single-plane crash in history with the loss of 520 lives, a Transport Ministry report released today said.

The 60-page report, however, said it is still unclear how the Boeing 747 malfunctioned or what the “impact” or its cause were.

A Transport Ministry investigating committee drew up the report after analyzing the JAL jetliner’s flight and voice recorders after the Aug. 12 disaster.

“The full-scale investigation will come later,” Keizo Hata, chairman of the committee, told reporters. He said the committee hopes that debris being collected from the crash site will yield further clues.

“At around 6:24:30 (p.m. Tokyo time) an abnormal impact took place,” the report said.

Sensor Also Broke

At the same time, a sensor recording the movement of the horizontal stabilizer also broke, the report said, although it was not clear whether the horizontal stabilizer itself malfunctioned.

The committee said it did not know what kind of impact had affected the aircraft about 12 minutes after it took off from Tokyo for the western city of Osaka.

Authorities have speculated that cracks in the pressure bulkhead caused air to rush out and destroy the tail fin but have not ruled out the possibility that an external object slammed into the vertical stabilizer.

At 6:24:34, a large boom sounded in the cabin and an alarm went off, apparently signaling a rapid loss of pressure, according to the voice recorder.

The jetliner crashed into a remote mountaintop about 70 miles northwest of Tokyo about half an hour later, killing all but four of the people aboard.