In March of 2002 and April of 2003, Proteus (a Scaled Composites design) flew as a NASA test-bed for UAV see-and-avoid technology with success. In 2002, the equipment (a Goodrich Skywatch HP Traffic Advisory System) sensed transponder-equipped aircraft and directed Proteus to avoid them. In the later tests an Amphitech OASys 35-Ghz primary radar system sensed the non-transponder-equipped aircraft involved in the test and relayed their positions to ground-based pilots who made course corrections as needed to avoid collisions. Last week, ASTM International (formerly the American Society for Testing and Materials) said it has completed a report to establish the fundamental design and performance specifications for an airborne sense-and-avoid (S&A) system for UAVs that would make it easier for them to operate in the National Airspace System. Much like the one tested onboard Proteus, the system would sense the presence of other aircraft in nearby airspace, and would take steps to divert the UAV from the other aircraft, the ASTM said. “This standard is a first step down the road of getting FAA approval for UAV S&A sensors and, ultimately, UAV ‘file-and-fly’ access to the national airspace similar to the process for manned aircraft,” said Ryan Schaefer, a systems engineer on the committee that issued the report. The report outlines parameters that are essential for any mechanical system that is designed to take the place of a human pilot while still maintaining an equivalent level of safety to that pilot, the ASTM said.
UAVs currently must operate in the National Airspace System with special authorization from the FAA. This permission, which is called a Certificate of Authorization, is contingent upon a list of requirements, one of which is that a UAV operator must provide a method to sense and avoid other aircraft. This can be satisfied in a variety of ways — ground observers, radar coverage, or a manned chase plane — but these methods are not always cost-efficient or mission-appropriate, says the ASTM. Adame said no chase planes are used in the current deployment. Adding a sensor to the UAV platform is a viable solution, but no onboard sensor has yet been certified by the FAA for UAV sense-and-avoid. “An S&A standard was needed for the industry to move forward, a standard to which all classes of UAVs can demonstrate compliance,” Schaefer said. Although initial users of the S&A specification will be within the UAV community, Schaefer says, it was designed to address the overall problem of collision avoidance in national airspace. Because of this, Schaefer feels that the standard will also be useful to develop S&A systems that assist human pilots in avoiding midair collisions.
