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Helicopter Brownout


Research performed in 2009 used Polarimetric Synthetic Aperture Radar (SAR) data from RADARSAT-2 and was analyzed for detection of helicopter brownout. Helicopter brownout occurs when downwash disturbs the dust and sand beneath the aircraft during takeoff, landing, and low altitude operations. Brownout may lead to pilot spatial disorientation and loss of control, causing helicopter damage or destruction, as well as personnel injury or death. The likelihood of helicopter brownout is related to soil moisture content, particle size distribution, and surface texture.

This research explored the polarimetric signatures of soils and determined whether these characteristics can be used to predict areas that are susceptible to helicopter brownout. Preliminary results show that helicopter brownout regions can be predicted by means of a simple threshold. 

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POL Brown out

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POW Brownout

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(Left) RADARSAT2 Image of brownout study area at Yuma Proving Ground.  (Right)  Polarimetric radar image (VV polarization) after new Brownout Algorithm threshold values are applied. Red = Brownout likely; Sienna = Unknown/Ambiguous; Green = Non-Brownout.

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The Use of Commercial Remote Sensing in Predicting Helicopter Brownout Conditions
Christine Kay Rabaja, Space Systems Operations
September 2009
Thesis Advisor: Richard C. Olsen
Second Reader: David M. Trask