Operator situational awareness and system safety

Makes a case for situational awareness (SA) as a critical attribute for evaluating the safety of human-machine systems by quantifying the level of SA acquired through the system interactions. It is suggested that SA is a dynamic concept that exists at the interface between an operator and the environment. A pragmatic definition of SA is given as a measure of the degree of dynamic coupling between a system operator and a particular situation. A tangible benefit of this perspective of SA is the focus on the inseparability of situations and awareness. The situated cognition perspective of SA focuses attention on both what is inside the head (awareness from a cognitive perspective) and also what the head is inside (the situation, which provides observable data). From this discussion, it is contended that SA is a critical safety attribute that can be used in the context of human-machine systems to quantify the relative safety of a human-computer interface. The paper has briefly presented aspects of a field study of a military air defence system and introduced an interactive system safety analysis method for evaluating both the process and the product of SA in context. The initial findings of the field study have already directed the developers to specify SA as a critical safety attribute for the replacement interface. The safety requirements for the replacement system also now specify that the replacement system must balance the requirements of both SA and usability in the design of interfaces and system interactions