Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: WEDNESDAY, July 13, 1994 TAG: 9407150024
SECTION: VIRGINIA PAGE: B6 EDITION: METRO
SOURCE: Associated Press
DATELINE: HAMPTON LENGTH: Medium
Researchers at the National Aviation and Space Administration's Langley Research Center built from scratch an airborne Doppler radar system that reliably spots deadly wind-shear hazards and gives pilots as much as a minute's warning.
Sixty seconds is a long time in an aircraft traveling four miles a minute.
The technology will help prevent air disasters such as the USAir crash July 2 at Charlotte-Douglas International Airport in North Carolina. A McDonnell Douglas DC-9 twin-jet crashed while landing in a thunderstorm, killing 37 passengers.
Investigators have not determined the cause of the wreck, but wind shear apparently was a factor. The pilots were warned of dangerous wind shear in the area less than two minutes before the crash. The plane was equipped with a wind-shear warning system, but the two pilots said they did not hear its alarm sound.
Airplanes depend upon a certain speed of airflow over their wings for flight. Wind shear is an abrupt change in wind speed or direction that can rob a plane of that airflow.
Scientists say thunderstorms can spew out a particularly deadly kind of wind shear called a ``microburst.'' Evaporating precipitation in a rising parcel of air that cools rapidly creates a microburst. The microbursts speed downward and spread out as the wind hits the earth.
Wind shear and gust fronts have caused or been a factor in at least 18 U.S. crashes and 575 deaths since 1970.
A Langley team called the ``Burst Busters'' developed, tested and provided the aviation industry its microburst detection system after seven years of research and development.
``This is the best we can do,'' said Jeremiah F. Creedon, head of Langley's Flight Systems Directorate. ``We might get that good again, but we can't get any better.''
The team used Albert, the first 737 off Boeing's production line, as their research station. The plane, named for Bill Cosby's Fat Albert character, already had distinguished itself in computerized cockpit and guidance systems for foul-weather landings.
The Boeing 737 became the most popular jet airliner ever built, but Albert has a few unusual features for a 737. It seats just 32 in what would ordinarily be the passenger cabin. Pilots, engineers, scientists and technicians fill the cabin's special research cockpit.
NASA and the Federal Aviation Administration began the wind-shear detection program in 1986 and began testing in flight three systems by 1990. The Doppler radar system was a clear winner over laser and infrared systems.
by CNB