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NSF/NCAR Aircraft Tests NASA Clear-Air Turbulence Sensor through Colorado Skies

David Hosansky
UCAR Communications
P.O. Box 3000
Boulder, CO 80307-3000
Telephone: (303) 497-8611
Fax: (303) 497-8610
E-mail: hosansky@ucar.edu

BOULDER -- An Electra research aircraft operated by the National Center for Atmospheric Research (NCAR) will attempt to detect dangerous clear-air turbulence using an onboard lidar sensor during test flights over the Rocky Mountain region between March 23 and April 10. The first test is scheduled for Tuesday, March 24, from Jefferson County Airport (near Broomfield) where the Electra is based.

The National Aeronautics and Space Administration (NASA) Dryden Flight Research Center is leading the experiment, called ACLAIM (the Airborne Coherent Lidar Advanced In-flight Measurement). Coherent Technologies, Inc. (CTI), of Lafayette, built the Doppler lidar sensor, which uses laser beams to track the motions of natural aerosol particles, some as small as a millionth of a meter, as they swirl in turbulent air several kilometers ahead of the plane. The National Science Foundation, NCAR's primary sponsor, owns the aircraft. NCAR's Larry Cornman will work with CTI scientists to analyze the data.

Because turbulence is short-lived, chaotic, and invisible to both the eye and radar, it is difficult to detect and forecast. During the experiment the Electra's crew will seek out turbulent areas predicted by expert meteorologists at NCAR and NASA Dryden. Unlike radar, which uses radio waves, CTI's lidar sensor will shoot a laser beam forward into expected turbulence in the aircraft's flight path. Dust particles and aerosols will reflect the laser beam back to the plane, characterizing the turbulent air motions ahead. When the plane encounters the choppy air, its response (bouncing, falling) will be measured and the atmospheric turbulence inferred will later be compared to that detected in the forward-looking lidar data. If the two mesh, the lidar could prove useful on commercial aircraft for detecting turbulence in time for pilots to instruct passengers and crew to be seated and fasten their seat belts before injuries occur.

Cornman has studied turbulence for over a decade. He devised the means for converting measurements of aircraft response motions into turbulence occurring in the atmosphere. United Airlines is currently testing his method on commercial aircraft. Says Cornman, "Not much is known about accurately detecting and forecasting turbulence. Through ACLAIM and turbulence research conducted at NCAR, we expect a clearer picture to emerge. Our goal is to provide accurate detection devices and reliable warnings that will make air travel safer and more comfortable in the future."

Turbulence plunged a United Airlines plane 30 meters last December, killing one passenger and injuring over 100 other people on a flight from Japan to Hawaii. In other incidents, turbulent air has ripped off airplane engines, snapped wings in two, hurled food carts to the ceiling, and broken passengers' and flight attendants' bones. Each year airlines face $100 million in turbulence-related costs.

NCAR is managed by the University Corporation for Atmospheric Research (UCAR) under sponsorship by the National Science Foundation. UCAR is a consortium of more than 60 universities offering Ph.D.s in the atmospheric or related sciences.

-The End-

Note to Editors: B-roll video footage and photos of the Electra will be available through NCAR Media Relations. Rod Bogue (NASA) and Allen Schanot (NCAR) will be available for short interviews at the airport Tuesday afternoon before takeoff. The aircraft may be filmed throughout the experiment with prior arrangement by calling David Hosansky, NCAR Media Relations, 303-497-8611.

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The National Center for Atmospheric Research and UCAR Office of Programs are operated by UCAR under the sponsorship of the National Science Foundation and other agencies. Opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any of UCARs sponsors. UCAR is an Equal Opportunity/Affirmative Action employer.

Last revised: Mon Apr 13 16:09:48 MDT 1998