As Unmanned Aerial Vehicles (UAVs) become more commonplace, there is a growing need for safer flight control software that allows for the UAV to understand and autonomously react to various unsafe flight conditions. Decision-making software must allow the aircraft to perform tasks such as detect and avoid, as well as detect and respond to critical system failures mid-flight. There is a lack of systems

engineering in the development of UAV control software safe enough to allow for integration of UAVs into the National Airspace. This lack of systems engineering is a big reason why UAVs are still too unsafe for everyday use. A model-based systems

engineering approach is needed to support system requirements, design, analysis, and verification and validation activities. In this thesis, we provide a model-based systems engineering approach toward a safety module for UAV control software that will allow for safe UAV integration into the National Airspace. System and simulation requirements and architecture are established, in addition to presentation of a collision detection and avoidance element, decision engine element, and ground impact hazard mitigation element. Detailed models and algorithms are developed for the ground impact hazard mitigation module. Furthermore, simulation results are presented to show the utility of the ground impact hazard mitigation module, which allows UAVs to react safely in the presence of various critical flight anomalies.