for example, an experienced employee who operates a five-axis machining center in a shop environment may take a two-week vacation. Her temporary replacement may be less experienced. this change in one component of the system (person/host) increases the probability of an accident. Such a simple example is easily understood. However, not all changes in patterns of are this simple. Some are so subtle quire a team of people, each with a different type of expertise.
the primary components of the systems model are the person/machine/environment,information,decisions,risks and the task to be performed. each of the components has a bearing on the probability that an accident model is illustrated in Figure 3-5