Wind Shear Warning Gear Will Make The Sky A Safer Place

One of an airline pilot's worst nightmares is wind shear. This deadly weather phenomenon occurs when a region of air rapidly cools, becoming heavy enough to plummet earthward like a runaway elevator. When the downdraft nears the ground, the wind spreads out in all directions. A plane flying into one of these "microbursts" encounters--in rapid succession--a strong head wind, a powerful downdraft, and a dangerous tail wind. The combination has been enough to smash dozens of aircraft into the ground, killing hundreds of people.

Now, scientists are close to perfecting high-tech airborne warning systems. Working with the Federal Aviation Administration and companies such as Lockheed Corp. and Rockwell International Corp., NASA researchers equipped a Boeing 737 with three different instruments for spotting wind shear--radar that picks up speeding raindrops, a laser that spies unusually fast-moving dust particles, and an infrared detector that looks for sudden temperature changes.

In late July, the researchers flew the test plane through up to 20 microbursts near Denver's Stapleton International Airport. In most cases, says Michael S. Lewis, deputy manager of NASA's wind-shear program, the instruments were able to detect microbursts 25 to 40 seconds before the plane encountered them, ample time for evasive maneuvers. The FAA is requiring all airliners to have such devices by the end of 1995.

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