Air traffic controllers grew increasingly worried as they tried over and over again to contact golfer Payne Stewart's plane as it flew on autopilot before crashing last October and killing all aboard.
Their vain attempts to contact the doomed plane, and efforts to get other pilots to help, are heard on three hours of audio tape made public today by the Federal Aviation Administration.
Both civilian and military pilots were able to see the Learjet as it flew steadily on, but none could get an answer from the pilot.
The last radio message from the plane: "Three nine zero bravo alpha," the simple acknowledgment that he had been cleared to climb to 39,000 feet, came at 9:27 a.m.
Six minutes later, air traffic control at Jacksonville, Fla., radioed the plane, getting no response. Another try three minutes later got no response and controllers quickly became concerned as the craft rose above its assigned altitude.
At 9:38 a Cubana airliner tried to raise Stewart's plane but advised the controllers he also got no answer.
"OK, thank you," the controller responded. "I think we got a dead pilot up there. He's through his altitude and off course now so we don't know what's going on."
It was not clear whether the controller literally thought the pilot was dead or meant his radio had gone dead. The FAA made no comment about the tapes.
The National Transportation Safety Board has not determined why the plane crashed Oct. 25 near Aberdeen, S.D., killing Stewart and five others on board.
Some aviation analysts, however, have speculated that Stewart's plane suffered from depressurization that incapacitated those on board after the plane took off from Orlando, Fla. The plane then continued on a northwest course, apparently on autopilot.
As time wore on, American Airlines and Delta Air Lines planes were asked to try their hand at contacting the plane when it was near them. Neither they nor military pilots who also could get an answer. Some reported seeing the plane.
The controller thanked the other pilots for their help in looking for "this guy that's unresponsive, climbing and
The tape was studied by the National Transportation Safety Board in its analysis of the disaster and then returned to the FAA. Its release is a routine post-crash step.
The tape does not include any sounds inside the cabin of the plane. However, the Safety Board previously reported that alarms were heard on the cockpit voice recorder tape, which also was reviewed. One that signals cabin pressure problems was sounding when the plane crashed in South Dakota. No one was heard talking on the 30-minute cockpit tape from the Learjet 35.
The human body has a limited ability to function above 10,000 feet because there is less oxygen in the air and there is less pressure to force that oxygen through the lungs. Airplanes are pressurized so tht the atmosphere inside never feels higher than about 8,000 feet even if the aircraft is flying much higher.
The FAA has reported that Stewart's plane climbed as high as 51,000 feet during its flight across the nation's heartland. The jet, which was supposed to have gone to Dallas, instead flew four hours some 1,400 miles to South Dakota before running out of fuel and crashing.
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