Air-India Tapes Show Abrupt End of Speech, No Bomb Proof : Indians See Blast Theory Support, Others Uncertain

Cockpit voice recorders from the downed Air-India jet indicate that cockpit conversation came to a sudden stop, but experts said today that the discovery does not mean the plane was bombed and that the possibility of a major structural defect remains.

Local news reports said the abrupt end of the cockpit conversation buttressed Indian officials’ theory that a bomb exploded in the jetliner before it plunged into the Atlantic on June 23, killing 329 people.

But Canadian investigators have said bodies and wreckage recovered from the ocean off the Irish coast gave no indication of an explosion, and a U.S. expert said the “black box” evidence is so far inconclusive.

“The cockpit voice recorder is just one piece of the puzzle. It is too early to say whether there was any kind of explosion,” the U.S. expert said, speaking on condition he not be identified.

Another foreign expert, who also demanded anonymity, said the public should not jump to conclusions about the sounds on the recorders. “Anything can sound like an explosion on tape . . . even someone coughing,” he said.

Sounds to Be Filtered

Aviation experts today turned to special equipment from India’s atomic research center to filter sounds registered by the voice recorder. Sources said the filtering process will focus on the last few minutes of the tape to determine if the sound of an explosion can be isolated.

The flight originated in Toronto and was headed to Bombay via Montreal and London. Two anonymous callers claiming to represent India’s Sikh minority claimed responsibility for blowing up the plane, but Sikh leaders said the calls were phony.

S. N. Sharma, secretary to the court of inquiry into the crash, told reporters that the preliminary examination of the tape showed conversation “came to an abrupt and sudden end.” The plane’s engine could be heard in the background, he said.

He did not elaborate. However, the abrupt end to the conversation would indicate that whatever caused the crash happened without warning and too quickly for the crew to react. The sounds of the aircraft’s engines would at least indicate that they were operating.

No Distress Signal

The craft had disappeared from radar screens without any distress signal radioed by the pilot.

The voice recorder and data flight recorder from the Boeing 747 were retrieved from more than 6,000 feet below sea level in waters near the Irish coast. The plane had been scheduled to stop in London for fuel.

Sharma said a complete analysis of the recorders will take a few more days.

He said the recording of conversations on the flight deck will be subjected to sound spectrum analysis. The airplane’s flight data recorder, a separate tape recording that monitors in-flight instrument readings, is being prepared for computer analysis.