Payne Stewart’s Last Flight: Explosive Decompression

One of the eeriest aviation tragedies in history happened in the fall of 1999. The story received big headlines not only because of the macabre circumstances surrounding the deaths of six people aboard a Learjet 35, but because one of the dead was popular golfer Payne Stewart.

In October 1999 Stewart boarded a Learjet for a flight from Sanford, Florida (near Orlando), to Dallas, where he was scheduled to golf in a tournament. Everything about the flight appeared to be going normally until the jet reached Gainesville at an altitude of 39,000 feet. At about that time, just 20 minutes into the flight, the plane stopped communicating with air-traffic controllers and failed to make a westward turn toward Dallas. Silently, it continued northwest.

When controllers, who had been trying for an hour, still couldn’t reach the plane, Air Force jets took off to intercept it and try to figure out what was wrong. The jet pilots caught up to the Learjet and watched it roller-coaster up and down, reaching as high as 45,000 feet at times. The inside of the jet’s windows were frosted over, an indication that no one on board was alive, or at least not able to scrape the frost away. The jet finally ran out of fuel and crashed in a remote field in South Dakota.

Payne Stewart's Last Flight: Explosive Decompression

The frost on the inside of the Learjefs windows tells most of the story. It points to an in-flight catastrophe that is the stuff of disaster films, but something very rare in real life—an explosive decompression.

Jetliners, and all high-altitude jets for that matter, are pressurized using excess air from the engines. Jet engines compress far more air than they can mix with fuel for burning and thrust. Designers put the excess compressed air to work, in part, to pressurize the cabin.

In order to provide a flow of fresh air and to give pilots a method for controlling cabin pressure, a valve in the cabin allows air coming in from the engines to rush out through a hole in the airplane. In the case of the Payne Stewart crash, investigators will look at the pressure valve to see if it somehow failed, causing the pressure in the cabin to plummet immediately.

If the valve did fail to regulate properly, or something else caused the pressure to drop, the water vapor inside the cabin would have suddenly condensed into a fog, and the temperature at 39,000 feet, about 60 degrees below zero Fahrenheit, would have caused the fog to freeze instantly onto everything in the cabin, including the windows.

Подпись: Turbulence One cause of explosive decompression is bird strikes, particularly those involving large, migratory birds such as Canada geese. Migrating geese have been spotted by pilots at altitudes well above 20,000 feet, and they are difficult to see until it's too late. A goose hitting the windshield of an airliner at cruise speed can shatter the glass and depressurize the cabin, forcing pilots to make a rapid emergency descent

More important for the passengers and crew, humans lose consciousness within 6 to 12 seconds at an altitude of 39,000 feet in case of decompression. The pilots were equipped with emergency oxygen masks, but if they were slow to react and put them on, they might have been knocked out within seconds and could have suffocated in a matter minutes. The same goes for Stewart and the other passengers in the cabin. Perhaps they were unable to see the emergency masks drop from the ceiling of the Learjet because of the fog. The point is, any delay in reacting would have been fatal.

Gruesome as it is to think of the “flying coffin” that Payne Stewart’s Learjet had become, we must remind ourselves that such tragedies are incredibly rare. Airplane mechanics are some of the best-trained and safety-oriented people in aviation, and many regard any system failure on an airplane they are responsible for, regardless how minor, as a personal affront.

Some accidents are like bolts of lightning, completely unpredictable and, for that reason, not worth worrying about beyond taking reasonable precautions. Other accidents, unfortunately, occur because of human error. What pilots can do in either event, though, is to make sure they continue to receive the very best training so that when the rare emergency happens, they’ll be ready to respond safely.

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► The macabre decompression disaster that killed Payne Stewart was caused by a very rare mechanical failure.

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