This chapter is about emergent safety hazards in engineering systems. These
hazards are those that emerge from a system without arising from any part of the
system alone, but because of interactions between parts. We distinguish two
approaches to analysing engineering systems: one is to view them as sociotechnical, and the other is to consider them as cyber-physical systems. We
illustrate a great deal of emergent hazardous behaviours and phenomena due to
unknown accident physics, malign actions, chemistry, and biology and due to
deficiencies in managements and organisations. The method that follows the
socio-technical view consists in the representation of a system by sequential
functionally unrelated processes that can in reality influence the performance of each other via sneak paths. The method that follows the cyber-physical systems
view focuses on the analysis of control loops (feedback, feedforward, positive,
and negative) and, especially, interrelated loops. The chapter explores also the
realm of security threats due to malign actions that can trigger safety-threatening events. And finally it gives general guidance for avoiding and eliminating safety hazards when designing engineering systems.
Autonomous systems strive to obtain salient features that include computer intelligence for obtaining situation awareness, decision support to a human navigator, or for facilitating autonomous decision-making in unmanned vehicles. This paper considers the case of autonomous marine surface vehicles, where high-quality decision support will be instrumental for obtaining a periodically unattended bridge and for approval of unmanned bridge operation with fallback through remote operation. The proposed design focuses on a sovereign-based architecture that facilitates safety, resilience and cyber-security. We address central elements of risk in the development and approval of autonomous systems; we analyze the challenges associated with testing, commissioning and maintenance of a highly complex cyber-physical system, and describe design principles for the sovereign agents architecture.