NTSB recovers cockpit voice recorder from airplane wreckage

Investigators have recovered what could prove to be a key clue in the odd and tragic crash of golfer Payne Stewart's Learjet: the cockpit voice recorder.

Investigators have recovered what could prove to be a key clue in the odd and tragic crash of golfer Payne Stewart's Learjet: the cockpit voice recorder.

The fuel-soaked recorder and its cracked cassette were recovered from the crash site just before sundown Wednesday, said Bob Benzon of the National Transportation Board.

The jet crashed into a field near Mina on Monday four hours after leaving Florida with Stewart and five other people aboard. All were killed, and investigators are trying to determine how the plane flew 1,400 miles (2,253 kilometers) across the country, apparently without someone at the controls.

Though the Learjet had no flight data recorder that could provide mechanical information, the cockpit voice recorder has a 30-minute loop that usually records over itself. Officials do not expect to hear anything about what happened when radio contact was lost and the plane veered off course because that happened hours before the crash.

But the voice recorder could have picked up sounds at the end of the flight that could tell a lot about what was happening in the plane, Benzon said. Information from the tape might be available as early as Friday.

"We're still confident we can get some good information off that tape," Benzon said.

Government officials have said one possible explanation for the crash is that the jet lost cabin pressure soon after taking off from Florida, causing everyone aboard to die or lose consciousness.

Benzon said investigators want to recover various parts of the plane's pressurization system, such as door and window seals and valves.

Benzon said investigators have learned that a device called the left-hand modulator valve, which takes heated air from the engine and runs it through the air-conditioning system to pressurize the cabin, was changed on the plane Saturday.

If the left-hand valve failed, the one on the right engine should have fed sufficient air into the cabin, he said.

Benzon said the valve was replaced Saturday to balance engine thrust on the plane - not because of any prior problem with cabin pressure. After the valve was replaced, the plane pressure-regulation system worked fine during a short flight on Saturday, he said.

Benzon said he does not know whether such a valve has ever been a factor in a crash.

Federal officials are looking into three other incidents involving Learjets that crashed under circumstances similar to Stewart's, The New York Times reported Thursday.

One of those crashes involved a German-owned Learjet that flew 1,600 miles (2,574 kilometers) from Vienna in 1983 before crashing into the Atlantic about 200 miles (322 kilometers) off Iceland, the Times said.

The other crashes occurred in Ohio in 1980 and in Mexico, the Times said. The date of the Mexico crash was unknown.

Benzon acknowledged there were similarities, but told the newspaper "that oxygen deprivation isn't the only thing that could have happened."

By Wednesday evening, investigators had removed more than half the wreckage from a crater that initially was 10 feet (3 meters) deep.

Searchers also found the engines, some passenger oxygen masks, fragments of cockpit instruments and some golf clubs. They had not found the pilots' oxygen masks. Benzon said investigators want to determine whether the masks dropped from the ceiling as they are designed to do during a loss of cabin pressure.