Standard takes on the challenge of defining how UAVs sense and avoid other aircraft

One of the challenges inherent in the design and construction of unmanned aerial vehicles (UAVs) is to establish the fundamental design and performance specifications for an airborne sense-and-avoid (S&A) system.  As its name implies, a sense-and-avoid 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 (FAA) 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 F2411, 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 an equivalent level of safety 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 currently 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 by the manned aviation community to develop S&A systems that assist human pilots in avoiding mid-air collisions.

FMI: www.astm.org