Be able to give the definitions of the following terms: Safety: [Absolute definition] Freedom from accidents or loss. [Relative definition] Freedom from unacceptable risk Accident: An undesired and unplanned event that results in a loss (including loss of human life, injury, property damage, etc.) that is important to a stakeholder. Incident: Incident (aka near miss) -- an event that involves no loss (or only minor loss) but with the potential for loss under different environmental circumstances. Hazard: [Leveson -- safer world definition] “state or set of conditions of a system (or an object) that, together with a particular set of worst-case environment conditions, will lead to an accident (loss event)” [Leveson, Safer World, p. 467] [Three components of a hazard -- Ericson] A hazard is compromised of the following three components, each of which must be present in order for the hazard to exist * Hazardous Element (HE) – The basic hazardous resource creating the impetus for the hazard, e.g., electric shock, explosives being used in the system, a harmful chemical, kinetic energy, etc. * Initiating Mechanism (IM) – The trigger or initiating event(s) (or states) causing the hazard to occur. This is the mechanism that causes actualization of the hazard from a dormant state to an actual mishap. * Target and Threat (T/T) – Person or thing that is vulnerable to injury or damage, along with the specific threat (harm) to the person/thing. [characteristics of a hazard that form the basis of risk] * Severity -- the worst possible accident (harm) that could result from the hazard given the environment in its most unfavorable state * Likelihood of occurrence of the accident (harm) Risk: combination of the likelihood of occurrence of harm and the severity of that harm State: A particular configuration of a system including the current values of system’s computer memory and resources, conditions and positions of mechanical components, etc. Event: A transition from one state to another, or something of particular interest that causes a transition from one state to another Reliability: the probability that a piece of equipment or component will perform its intended function satisfactorily for a prescribed time and under stipulated environment conditions. [Leveson, Safeware, p. 172] * explain the different between safety and reliability (give examples)