Airplanes without pilots on board will one day navigate safely in skies filled with all types of aircraft. Sensors will enable remotely piloted aircraft to be steered away from other aircraft by operators in control rooms on the ground.

NASA and several partners in industry have already test flown an aircraft from a ground station, using special radar and radios to locate and avoid other piloted test airplanes that approached the remotely piloted plane. The most recent flight research took place in the skies near Mojave, Calif., in April 2003. A specialized aircraft called Proteus was operated by a pilot in a control room miles away from where the airplane was flying on a special test range over the desert. Other airplanes, including a fast NASA F/A-18 jet, deliberately made passes toward the Proteus. Although these approaches had a margin of safety to ensure they would not actually collide, they were still close enough to prove that radar in the nose of Proteus could identify potential collision hazards with enough clarity, and in time for the ground operator to change course in a safe direction.

The April flight tests were important because they showed a remotely piloted aircraft can detect other airplanes that are not sending out any signals to show their locations. A year ago, NASA and its research partners flew tests with Proteus using a radio-based detection system that identified the presence of other airplanes that were using transponders to help controllers locate them. Transponders are used regularly by airliners and many other aircraft. A transponder sends a radio signal to enable air traffic controllers to keep track of aircraft using this device in flight.

Uninhabited aerial vehicles (UAVs) are already expanding the horizons of flight. They can fly long-endurance missions that would fatigue an onboard pilot. They can fly high, where oxygen would be necessary for human inhabitants. They can fly into dangerous locations without risking the lives of the operators, who are safe in a control room far away. Because they do not need to support the well-being of a pilot onboard, UAVs can be made smaller, lighter, and with fewer complex systems than those required of piloted aircraft. This allows greater performance plus less expensive aircraft. UAVs already have military reconnaissance duties, and are being evaluated for a variety of civilian applications including communications relay and environmental monitoring.

After the use of remotely-piloted aircraft is made routine in the airspace system, NASA and its partners want to automate the detection devices to enable safe operation of autonomous aircraft without any human intervention from takeoff to landing. Safety comes first; if a remotely piloted or autonomous aircraft loses contact with its ground operator or experiences other guidance difficulties in flight, the aircraft has an onboard capability to fly to a safe place while technicians fix the problem. This could be as simple as circling in the sky while other air traffic in the area is advised of the uninhabited aircraft's location.

More detect, see and avoid flight tests are planned, as NASA and its partners look for ways to enable UAVs to share the skies with all aircraft.

Want to see photos of Proteus and the other aircraft used in the April detect, see and avoid (DSA) tests? You can go to: http://www.dfrc.nasa.gov/Gallery/Photo/Proteus/Small/index.html.

Want to learn more about this exciting research? You can read about DSA on the NASA Dryden Flight Research Center web site at: http://www.dfrc.nasa.gov/Newsroom/NewsReleases/2003/03-21.html (also 03-20) in the News Release section.