This paper deals with Detect-and-Avoid (DAA) technology that are needed to integrate Unmanned Aircraft System (UAS) in the National Airspace System (NAS). In order to meet the demands of the UAS in civil purpose, technologies and regulation research and development are being actively carried out by advanced countries in aviation such as UAS and Europe countries. For the traffic avoidance, which is the biggest technical difficulty for UAS integration, the whole system form aircraft detection/recognition, collision prediction/warning, and avoidance decision/maneuver is presented and operated by flight test. For the recognition/detection of intruder aircraft, we takes information of cooperative aircraft using ADS-B and detected non-cooperative aircraft using the EO sensors. It has predicted and warned of collision by measuring collision predicted time. Operator in Remote Pilot Station (RPS) can decide the traffic avoidance using collision alerts.