Northwest system helps pilots avoid turbulence

December 30, 1997
Web posted at: 10:59 p.m. EST (0359 GMT)

NEW YORK (CNN) -- About one minute after United Airlines Flight 826 was violently rocked by air turbulence over the Pacific Ocean Sunday night, a Northwest Airlines plane flew safely 4,000 feet higher thanks to turbulence prediction methods used by Northwest.

One passenger was killed and more than 100 were injured when the United 747 encountered rough air described by the pilot as the most severe turbulence he had experienced in his 31-year career.

The plane with 374 passengers and 16 flight attendants was en route from Tokyo to Honolulu when it encountered the turbulence.

An initial examination of the flight data recorder showed that the first hour and a half of the United flight was normal. The captain reported light turbulence and had just asked to fly from about 30,000 feet to a higher altitude when the plane was pushed upward with a powerful force.

CNN's Christine Negroni examines the dangers of air turbulence.

Although initial reports put loss of altitude at 1,000 feet, the data shows that the plane actually rose and fell only 100 feet during the event.

Meanwhile, a Northwest Airlines plane flew safely 4,000 feet above the United plane. Turbulence prediction methods developed by Northwest enabled the airline to instruct pilots to fly at 34,000 feet, an altitude higher than the location predicted for the turbulence.

Observers say Northwest's weather forecasters consider turbulence a significant safety issue and routinely urge pilots to fly around trouble spots.

The flight data recorder provided more information on what happened to the United 747

"It's a system we believe is effective, over many years of use," said Clay Foushie, a spokesman for Northwest. "We have a lesser probability of encountering these events if we use such a system."

Investigators are making a more thorough study of the United plane's flight recorder, and the plane's crew will be interviewed before the end of the year. In addition, the Federal Aviation Administration and airlines are working to more accurately predict the difficult to detect, sometimes invisible, phenomenon of turbulence.

Correspondent Christine Negroni contributed to this report.

Related stories:

• NTSB examines data recorder from turbulent United flight - December 30, 1997
• NTSB investigates United Airlines plunge - December 29, 1997
• 1 dead, scores hurt after United jet hits turbulence - December 28, 1997

Related sites:

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• National Transportation Safety Board (NTSB)
• Federal Aviation Administration
• United Airlines
• Boeing Company
  • Boeing 747 Background

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