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Unmanned Air Vehicle Committee Develops Airborne Sense-and-Avoid Standard

One of the challenges inherent in the design and construction of unmanned aerial vehicles is to establish the fundamental design and performance specifications for an airborne sense-and-avoid system. As its name implies, an S&A system would sense the presence of other aircraft in nearby airspace, and would take steps to divert the UAV from the other aircraft in accordance with Federal Aviation Administration requirements. A new standard developed by ASTM Committee F38 on Unmanned Air Vehicle Systems addresses the issues involved in designing S&A systems.

The standard, ASTM F 2411, Specification for Design and Performance of an Airborne Sense-and-Avoid System, outlines specific parameters that are essential for any mechanical system that is designed to take the place of a human pilot while still maintaining a level of safety equivalent to that pilot. It also provides a single definition for equivalence that can be applied to all UAVs that require sense-and-avoid capability.

“By addressing these issues, the standard sets a performance threshold for the technology as well as the fundamental methods to prove compliance,” says Ryan Schaefer, senior systems engineer, SRA International, and member of Subcommittee F38.01 on Airworthiness. He also notes that the subcommittee welcomes any comments or participation from parties interested in this standard or others being developed.

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. While this can be satisfied in a variety of ways — ground observers, radar coverage, or a manned chase plane — these methods are not always cost-efficient or mission-appropriate. 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 UAV can demonstrate compliance,” says Schaefer. “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.”

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 the manned aviation community to develop S&A systems that assist human pilots in avoiding mid-air collisions.

For further technical information, contact Ryan Schaefer, SRA International, Alexandria, Va. (phone: 703/684-2900). Committee F38 meets Nov. 8-9 during the November Committee Week in Washington, D.C. For membership or meeting details, contact Pat Picariello, ASTM International (phone: 610/832-9720). //

Copyright 2004, ASTM International