Drucella Andersen 
Headquarters, Washington, D.C.                                              
July 13, 1992
(Phone:  202/453-8613)

Michael Finneran
Langley Research Center, Hampton, Va.
(Phone:  804/864-6126)


RELEASE:  92-108

NASA STARTS MICROBURST WINDSHEAR WARNING FLIGHT RESEARCH

   NASA today started the first flight test in Denver of a 
laser-based sensor to provide airline pilots with advance 
warning of "microbursts" that can harbor potentially dangerous 
windshears.

   A microburst is an intense downdraft that produces strong 
divergent winds near the ground, typically for a short duration 
and over a relatively small area.  When an airliner is taking 
off or landing, a microburst can force the plane into the 
ground before the flight crew can take proper corrective 
action.

   "NASA's Boeing 737 research aircraft mounts several 
instruments to detect hazardous windshear," said Herbert 
Schlickenmaier, Program Manager at NASA Headquarters.  "We are 
most interested in sensors that will provide a minimum of 20-40 
seconds advanced warning of microburst windshear conditions, 
which NASA research has shown is enough time for pilots to 
avoid the hazard."

   Schlickenmaier noted that the Federal Aviation 
Administration (FAA) has mandated airlines must select and 
install an approved microburst detection system on their 
aircraft by the end of 1995.

   The flights in Denver will take place July 13-27.  Tests in 
Orlando, Fla., will occur from early August through early 
September.  During the deployments, the 737 research plane will 
be directed toward microbursts using experimental ground-based 
Doppler radar that also is designed to spot windshear.


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   During the tests, scientists and engineers aboard the NASA 
Boeing 737 will evaluate how well the laser-based Doppler LIDAR 
(light detecting and ranging) system and other sensors seek out 
microbursts.  The 737 will fly at low altitude directly into 
microbursts and other severe weather conditions under strict 
safety criteria.

   The flight tests are part of a $20-million-plus 1986 
research  agreement signed between NASA and the FAA.  The 
agreement calls for the development of technology for airborne 
windshear detection and avoidance.  The 737 flights, managed by 
NASA's Langley Research Center, Hampton, Va., are the final 
phase of the joint program.

   The Doppler LIDAR system, to be flight-tested for the first 
time in Denver and Orlando, reflects energy from "aerosols" 
(tiny particles) moving inside a storm.  NASA researchers also 
expect the tests to yield more data on two other airborne 
windshear sensors tested last year.

   A microwave radar system finds microbursts by measuring 
sudden, large changes in the speed of raindrops in storm cells 
ahead of the airplane.  Another system uses an infrared light 
sensor to detect microbursts by measuring air temperature 
differences ahead of the plane.

   The flights also will test a Langley-developed data link 
between ground weather radar and the 737.  Researchers are 
developing a system that automatically sends windshear data 
from ground radar to a display in an airplane cockpit.  
Currently, warnings from the ground usually are relayed by 
voice -- a slower, less precise method.

   Dr. Roland Bowles is the Project Manager at Langley Research 
Center.  Dick Yenni is forward deck pilot on the NASA 737, and 
Michael Phillips is Co-pilot.  Lee H. Person, Jr. is the 
Research Cockpit Pilot. 

                             -end-

NOTE TO EDITORS:  A 3/4" video clip on windshear and the NASA 
flight tests is available to media by calling 202/453-8594.  
Still photos are available by calling 202/453-8375.  A graphic 
illustrating windshear is available by calling 202/453-2754. 

Color:  92-HC-424 to -433

B&W:  92-H-474 to -483