Systems and methods for collision avoidance in unmanned aerial vehicles are provided. In one embodiment, the invention relates to a method for collision avoidance system for an unmanned aerial vehicle (UAV), the method including scanning for objects within a preselected range of the UAV using a plurality of phased array radar sensors, receiving scan information from each of the plurality of phased array radar sensors, wherein the scan information includes information indicative of objects detected within the preselected range of the UAV, determining maneuver information including whether to change a flight path of the UAV based on the scan information, and sending the maneuver information to a flight control circuitry of the UAV.