Don Nolan-Proxmire
Headquarters, Washington, DC            December 18, 1996
(Phone:  202/358-1983)

Michael Mewhinney
Ames Research Center, Mountain View, CA
(Phone:  415/604-3937)


RELEASE:  96-262


NEW COLLISION AVOIDANCE SYSTEM HELPS HELICOPTER PILOTS

     NASA has conducted flight tests of a new collision 
avoidance radar system intended to help helicopter pilots fly 
more safely when operating close to the ground or in poor 
weather conditions.

     Developed by engineers at NASA's Ames Research Center, 
Mountain View, CA, and Honeywell Military Avionics, 
Minneapolis, MN, the new 35 GHz Millimeter-Wave (MMW) Radar 
Forward Sensor is designed to detect obstacles in an 
aircraft's flight path and provides a cockpit display to help 
avoid them.  Although developed for helicopters, the new 
radar system has potential uses for all aircraft.

     "Collision avoidance is of concern to all aircraft, 
requiring the detection of hazardous terrain or obstacles in 
sufficient time for clearance maneuvers," said Richard 
Zelenka, group leader for NASA's Automated Nap-of-the-Earth 
(NOE) Program.

     "The collision avoidance requirement is even more 
demanding for helicopters, as their unique capabilities 
result in extensive operations at low altitude, near to 
terrain and hazardous obstacles," he said.

     Although existing cockpit "enhanced vision" systems are 
acceptable for final approach and landing, they are 
insufficient for general flight operations, particularly 
helicopter missions and systems requiring automated warnings, 
according to Zelenka.

     Military helicopter pilots, for example, who often fly 
below tree level, face unique guidance and control tasks, 
such as aircraft concealment, obstacle avoidance and real 
time mission planning.  These tasks require a high degree of 
pilot concentration, which is intensified during bad weather 
and during stressful tactical situations.  "Automation of 
some of these tasks can reduce pilot workload, while 
enhancing safety," Zelenka said.

     "Although the program originally had a military focus, 
some of the technological advances inherent for automating 
NOE flight have significant potential for civil applications 
as well, such as emergency medical service helicopters, 
conventional and high-speed transports, remotely-piloted 
aircraft and planetary vehicles," Zelenka said.  Other 
potential users include aerial firefighters, search and 
rescue aircraft and helicopters serving unique roles, such as 
oil rig helicopter operators.

     Flight tests of the collision avoidance system were 
recently conducted aboard the NASA/Army Rotorcraft Aircrew 
Systems Concepts Airborne Laboratory (RASCAL) UH-60 research 
helicopter.  The RASCAL is equipped with satellite navigation 
systems, digital data recorders, panel-mounted displays in 
the cockpit and crew area and a Silicon Graphics imaging 
system for generating high fidelity graphics.  The new radar 
system was mounted on the nose of the aircraft and a color 
video camera was mounted adjacent to the radar to document 
the test conditions.

     "By using existing 4.3 GHz radar altimeter components to 
perform the sensor's transmit and receive functions, the 
system will yield a low-cost, highly-reliable radar system," 
said Larry Almsted, Honeywell Program Manager.  "Our emphasis 
has been on affordability from the beginning," Almsted added.  
The radar altimeter signal is converted to 35 GHz and 
transmitted as a scanning, three-dimensional pencil-beam 
through a small twist-reflector type antenna measuring only 
nine inches in diameter.

     Flight tests were conducted over flat and moderately 
rugged mountainous terrain.  While airborne, the new radar 
system constructed a database of the terrain and obstacles it 
detected in the aircraft's flight path and produced a three-
dimensional synthetic perspective grid panel display for the 
pilot.  Zelenka said the new radar system also operates well 
in bad weather conditions such as fog or rain, when 
visibility is poor.

     The new radar system and cockpit display have been 
developed under NASA's Automated NOE program, with the goal 
of developing technologies to improve the effectiveness and 
safety of low altitude helicopter missions. 

                            -end-