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Michael Braukus
Headquarters, Washington           April 8, 2003
(Phone: 202/358-1979)

Alan Brown
Dryden Flight Research Center, Edwards, Calif.
(Phone: 661/276-2665)

Patti Bird
Scaled Composites, LLC, Mojave, Calif.
(Phone: 661/824-4541)

RELEASE: 03-134

RESEARCHERS ENCOURAGED BY COLLISION-AVOIDANCE TEST RESULTS

     NASA and industry researchers are increasingly 
confident a pilot in a remote ground station can safely 
detect and avoid collisions between an Unmanned Aerial 
Vehicle (UAV) and other aircraft. Detect, see and avoid 
technology is vital if remotely piloted or autonomous 
aircraft are to be integrated into the airspace system 
shared with inhabited aircraft.

The latest round of flight tests, sponsored by NASA's Dryden 
Flight Research Center, Edwards, Calif., under the 
Environmental Research Aircraft and Sensor Technology 
(ERAST) program, took place April 1-4 near Mojave, Calif.

"The goal of the test was to be able to make a decision 
based on radar data in enough lead time to maneuver the test 
aircraft to avoid a close encounter with the intruder 
aircraft," said Glenn Hamilton, UAV subsystems project 
manager at Dryden. 

The Proteus aircraft, built by Scaled Composites of Mojave, 
with safety pilots on board, but controlled from the ground 
like a true UAV, was repeatedly directed away from 
conflicting flight paths, with a variety of aircraft, some 
of which did not emit any signals to show their positions.

In all 20 scenarios flown, the Proteus ground operator was 
able to detect the presence of other aircraft that posed the 
potential for collisions, maneuvering the test aircraft to 
keep the intruding aircraft from entering a 500-foot bubble 
of safe airspace surrounding Proteus.

The conflicting aircraft flew at greatly different speeds, 
from a NASA F/A-18 high-speed jet to several types of 
general aviation aircraft including an unpowered sailplane.

"The detection ranges were a little less than we expected, 
but varied greatly from about 2.5 to 6.5 nautical miles, 
based on the structure and radar cross-section of the target 
aircraft," Hamilton recalled. "We picked up the F/A-18 
farther out, due to its larger radar signature, but because 
of its higher speed, it didn't give us a whole lot of extra 
time to make an avoidance decision. On one head-on scenario, 
we had a 610-knot closure speed, not a whole lot of time to 
decide," he said. 

The use of radar to detect these aircraft included one 
surprise. A 1940s-vintage fabric-covered Stinson Voyager 
made a larger-than-expected radar signature, possibly due to 
its large aluminum-covered tail surfaces.

The recent tests follow a series last year near Las Cruces, 
N.M., in which Proteus's remote pilot, using data from 
another detection device, was able to avoid conflict with 
aircraft that used transponders to identify their positions. 
Researchers are encouraged by the results of both test 
series, but say more work is required before a refined, 
operational detect, see and avoid system can be fielded.

-end-

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