  Existing definitions and associated conceptual frameworks for computer-based
system safety should be revisited in light of real-world experiences from
deploying autonomous vehicles. Current terminology used by industry safety
standards emphasizes mitigation of risk from specifically identified hazards,
and carries assumptions based on human-supervised vehicle operation. Operation
without a human driver dramatically increases the scope of safety concerns,
especially due to operation in an open world environment, a requirement to
self-enforce operational limits, participation in an ad hoc sociotechnical
system of systems, and a requirement to conform to both legal and ethical
constraints. Existing standards and terminology only partially address these
new challenges. We propose updated definitions for core system safety concepts
that encompass these additional considerations as a starting point for evolving
safe-ty approaches to address these additional safety challenges. These results
might additionally inform framing safety terminology for other autonomous
system applications.
