No voices heard on Stewart recorder

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The Independent Online

The cockpit sound recorder recovered from the crash of Payne Stewart's jet contains no voices, but federal investigators said that alarms, including one signalling problems with cabin pressure, sounded before his Learjet crashed.

The cockpit sound recorder recovered from the crash of Payne Stewart's jet contains no voices, but federal investigators said that alarms, including one signalling problems with cabin pressure, sounded before his Learjet crashed.

The National Transportation Safety Board said tape noises are consistent with alarms on the Learjet 35 that warn pilots when the cabin altitude exceeds normal levels or when the plane is flying at a speed or angle that cannot sustain flight.

The NTSB has not determined why the plane crashed on 25 October in a field near Aberdeen, South Dakota, killing Stewart and five others. But aviation analysts have speculated that the plane suffered from fatal depressurisation.

The human body has a limited ability to function above 10,000 feet because there is less oxygen, and less pressure to force the oxygen into the bloodstream. Aeroplanes are pressurised so that the atmosphere inside never feels higher than about 8,000 feet.

Federal Aviation Administration officials said the plane climbed as high as 51,000 feet. The jet took off from Orlando, Florida, bound for Dallas, and flew for four hours - some 1,400 miles - before running out of fuel. Controllers last talked to the pilots when they confirmed an instruction to climb to 39,000 feet.

A Learjet spokesman said a cabin altitude horn in the Learjet 35 sounds when cabin pressure altitude reaches 10,000 feet. Under normal conditions when the alarm sounds, pilots correct the problem by activating an emergency pressurisation system, donning their oxygen masks and initiating descent.

NTSB investigators said various fragments, including parts of the pressurisation and oxygen systems, will be examined in coming weeks. The plane's engines, which were severely damaged, have been taken to the manufacturer for inspection.

Investigators have completed their work at the accident site and are interviewing passengers who took earlier flights on the plane as well as pilots who had previously flown the aircraft.

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