28 Proceedings Spring 2025 to obtain permission to operate within a strictly defined airspace. Many operators rely on the ASTM International Standard known as ASTM F3442M/F3442- 231 for safety determinations. Formally known as American Society for Testing and Materials, this standard defines the vol- ume of airspace for remaining “well clear” of other air- craft and further defines what constitutes a near midair collision (NMAC). Well clear is defined by ASTM as being more than 2,000 feet from an object laterally and more than 250 feet vertically. The NMAC boundary is 500 feet laterally and 100 feet vertically. The standard also includes the math- ematical formulae for determining risk ratios for loss of well clear and near midair collisions. BVLOS and DAA background for the Coast Guard Currently, the only Coast Guard program of record for UAS to operate BVLOS is onboard the national security cutters (NSC) using the Boeing Insitu ScanEagle UAS. The ScanEagle has proven successful for the Coast Guard for several years. However, the system currently relies on an air search radar (ASR) and a qualified radar operator onboard to meet Department of Defense requirements to segregate airspace. When operating outside of 12 nauti- cal miles (nm), the Coast Guard can operate in interna- tional airspace under the regulations referred to as “Due Regard.”2 NSC ScanEagle operations within 12 nm of U.S. shores are conducted with approval from the FAA. The FAA has yet to establish firm rules facilitat- ing full integration of UAS into the National Airspace System. For UAS to support cutter classes without ASR capabilities, such as Coast Guard fast response cutters, and still meet Due Regard requirements, an approved DAA technology is required onboard the UAS. DAA Technology Types Currently Available The main challenge with integrating DAA technologies onboard small uncrewed aircraft systems (sUAS) is the size, weight, and power (SWAP) requirements. These air- craft are small with limited power, minimal weight, and less space available for managing the center of gravity for flight operations. There are generally three types of DAA technologies available: • Radar: Typically bulky and heavy for sUAS, it has a limited field of view—120 degrees per array—and a transmitter with a large power draw that creates challenges with command-and-control links, but works well in restricted-visibility conditions like clouds or fog. • Visual/Camera-Based: Current technology only has a daytime camera solution, restricting opera- tional periods, and requires multiple cameras for obtaining a 360-degree field of view. It has a passive, low power draw, but it is challenged in restricted-visibility conditions. • Acoustic: This type has a low power draw, 360-degree field of regard, day or night opera- tion, and works well in restricted-visibility con- ditions. After in-depth market research, the RDC program managers selected an acoustic system as the best option to meet DAA standards in 2020 and proceeded with fur- ther investigation. What is Required to Fly BVLOS? UAS platforms must be selected based on missions. There are many options to choose from, ranging from low-cost quadcopters with relatively short ranges that operate on Li-ion batteries, to long-range platforms with commen- surately high purchase and operating costs, such as an MQ-9 Reaper or the MQ-4C Triton. For an sUAS, the RDC chose AeroVironment Puma platforms which are small, fixed-wing aircraft that can land in water. For flight deck-equipped cutters, a medium UAS, like the L3 Harris FVR-90, would be appropriate. These types typically fly faster and longer than an sUAS but require a larger area to operate from. The RDC chose An FVR90, a medium UAS with Passive Acoustic NonCooperative Aircraft System acoustic probes installed, is in flight. Coast Guard photo
