As a prerequisite to significantly reducing restrictions on unmanned aircraft systems (UAS) flight operations, ACAS Xu (Airborne Collision Avoidance System) is the sole technology that will allow UAS to meet the United States law and international regulations that require all vehicles to see and avoid other air traffic. Since UAS lack a pilot on board to meet this requirement, a technical solution is required in order to allow unrestricted UAS operations in civil airspace. To date, a technical solution to address this requirement does not exist. The ACAS Xu is being developed to provide UAS with the capability to detect and track other nearby aircraft and provide ground operators with safety alerts in order to maintain separation from other air traffic and avoid potential mid-air collisions with manned aircraft as well as other UAS. This system is sensor agnostic and tunable for safe and effective collision avoidance advisories across the range of UAS vehicle and surveillance system performance characteristics. ACAS Xu is designed to coordinate maneuvers and interoperate with collision avoidance systems on all other manned and unmanned aircraft.