The U.S. has the safest national airspace system (NAS) in the world, and an equivalent level of safety and confidence will be required to introduce synchronous manned and unmanned aircraft operations. Unmanned aircraft systems (UAS) offer incredible opportunities for safer, more precise, economical improvements in critical infrastructure inspection, area surveillance, disaster response, law enforcement, package delivery and untold use cases yet to be discovered. So how do you replace or even improve the level of safety a pilot in the cockpit once provided for an aircraft now weighing only tens of pounds? Answering this question has been one of the major roadblocks preventing UAS operations Beyond Visual Line of Sight (BVLOS). Aircraft attempting to be cooperative may broadcast their position via ADS-B, and services are available to provide that information to UAS operators. However, detecting non-cooperative aircraft require a sensor onboard the UAS that must be small, light weight and low power, or sensors on the ground that are also easy to install, and affordable to make any sense of a scalable business case. Oh, and they must provide 360 degrees of coverage and detect aircraft many kilometers away. SARA’s aeroacoustics physicists and engineers have developed both airborne and ground based detect and avoid solutions to help solve these challenges. As robotics mature, sensing modalities mimicking human behavior become more and more prevalent. How do you first detect an aircraft? Most always you first hear it which cues you to look in the direction where the sound is coming from. An array of super sensitive microphones do the same, except they can hear much farther away, and advanced algorithms process incoming sounds of propeller blades and engine noise to enable tracking aircraft at long distances. Additional algorithms determine if any of these nearby aircraft pose a collision threat and if so, warns the UAS pilot or commands an evasive maneuver to remain well clear.