The unrestrained design space for unmanned aerial systems (UAS) presents challenges to accurate safety assessment and the assurance of development to appropriate levels of rigor within those systems. The established safety and development assurance standards and practices were developed for vehicles operating in highly controlled conditions with continuous oversight. The very nature of unmanned systems introduce new failure conditions, even in those systems operating within the strict rules of the National Airspace System (NAS), particularly failures of control and command, situational awareness, and control security. Beyond those, the new concepts of operation being conceived by UAS developers introduce their own new set of considerations with regards to operating in uncontrolled airspace, often in close proximity to bystanders. These new concepts require new technologies beyond those currently supported by the hardware and software development assurance processes. However, the established standards and practices of aircraft development assurance and safety assessment can be adapted for the broader world of UAS applications, provided that the considerations driven by the new concepts of operation can be identified and properly analyzed. The two major challenges to this are the identification and determination of criticality of failure conditions in the new operational environment, and the analysis of the new architectures, technologies, and the “new and novel” mitigations that will be possible from them. If these challenges can be addressed, it will be possible to apply established principles of development assurance and system safety to these new products, and thus give confidence both to the developers and the regulators tasked with certificating them.
