Current unmanned systems (UxSs) use different communication systems and have limited autonomy, which can contribute to interoperability problems and limit the degree to which information collected by these systems can be shared with warfighters and other UxSs operating in the same area. UxSs may also face survivability and mission effectiveness challenges when they operate in contested environments or against adversaries with significant electronic or cyber warfare capabilities. Improving UxS autonomy can address these challenges. This report identifies a partially open systems architecture (POSA) approach that can improve system interoperability and autonomy. A POSA reference model is proposed for unmanned aircraft vehicles that can enable new autonomous capability modules to be inserted into the system.