As stated by Modugno et al, “A safe system is one
that is free from accidents or unacceptable losses.” [5] An
accident is an undesired and unplanned, but not necessarily
unexpected, event that results in, at least, a specified
level of loss [3]. A loss is damage to or destruction
of property or injury to or death of a living being, particularly
a human being. Any system operates in an environment.
A hazard in a system is a state or condition of the
system that can, in the presence of a stimulus from the
environment, lead to an accident or loss.