Small Unmanned Aircraft Systems (sUAS) offer many potential benefits to society but also pose a dangerous mid-air collision hazard. Safely integrating into shared airspace will require sUAS to perform Collision Avoidance (CA), one of the primary components of Detect and Avoid (DAA) technologies. This paper performs a Monte Carlo simulation of close encounters between sUAS and manned aircraft to evaluate the safety and alerting rates of three CA system architecture options: manned aircraft avoiding sUAS, sUAS avoiding manned aircraft, and both types of aircraft avoiding each other. Novel CA policies based on ACAS X are introduced for sUAS. These policies enable sUAS to perform escape maneuvers with far lower vertical climb capabilities than what is expected by current CA systems.