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43 Acceptable Level of Risk: likelihood of an event when proba- bility of occurrence is small, whose consequences are so slight, or whose benefits (perceived or real) are so great, that individ- uals or groups in society are willing to take or be subjected to the risk that the event might occur. Accident: an unplanned event or series of events that re- sults in death, injury, or damage to, or loss of, equipment or property. Consequence: the direct effect of an event, incident, or acci- dent. In this study it is expressed as a health effect (e.g., death, injury, exposure) or property loss. Fatal Injury: any injury that results in death within 30 days of the accident. Hazard: the inherent characteristic of a material, condition, or activity that has the potential to cause harm to people, property, or the environment. Hazard Analysis: the identification of system elements, events or material properties that lead to harm or loss. Hazard analy- sis may also include evaluation of consequences from an event or incident. Hull Loss: airplane totally destroyed or damaged and not repaired. Incident: a near miss episode, malfunction, or failure with- out accident-level consequences that has a significant chance of resulting in accident-level consequences. Likelihood: expressed as either a frequency or a probability. Frequency is a measure of the rate at which events occur over time (e.g., events/year, incidents/year, deaths/year). Probabil- ity is a measure of the rate of a possible event expressed as a fraction of the total number of events (e.g., one-in-ten-million, 1/10,000,000, or 1 Ã 10-7). Major Accident: an accident in which any of three condi- tions is met: the airplane was destroyed; or there were multi- ple fatalities; or there was one fatality and the airplane was substantially damaged. METAR: aviation routine weather report. Nonconformity: non-fulfillment of a requirement. This in- cludes but is not limited to non-compliance with Federal reg- ulations. It also includes an organizationâs requirements, policies, and procedures, as well as requirements of safety risk controls developed by the organization. Overrun or Overshoot: a departure of the aircraft from the end of the intended landing runway surface. Quantitative Risk Analysis: incorporates numerical esti- mates of frequency or probability and consequence. Risk: the combination of the likelihood and the consequence of a specified hazard being realized. It is a measure of harm or loss associated with an activity. Risk Analysis: the study of risk in order to understand and quantify risk so it can be managed. Risk Assessment: determination of risk context and accept- ability, often by comparison to similar risks. Runway Criticality: term introduced in this study to repre- sent the relationship between the runway distance required by a given aircraft and specific operational conditions, and the runway distance available for that operation (landing or take- off). Runway criticality is represented mathematically by the ratio between the runway distance required and the runway distance available. A higher ratio means a lower safety margin and greater operation criticality. Safety: absence of risk. Safety often is equated with meeting a measurable goal, such as an accident rate that is less than an acceptable target. However, the absence of accidents does not ensure a safe system. To remain vigilant regarding safety, it is necessary to recognize that just because an accident has not happened, it does not mean that it cannot or will not happen. Definitions
Safety Management System: the formal, top-down business- like approach to managing safety risk. It includes systematic procedures, practices, and policies for the management of safety (including safety risk management, safety policy, safety assurance, and safety promotion). Safety Risk Management: the systematic application of poli- cies, practices, and resources to the assessment and control of risk affecting human health and safety and the environment. Hazard, risk, and cost/benefit analysis are used to support de- velopment of risk reduction options, program objectives, and prioritization of issues and resources. Substantial Damage: damage or failure that adversely affects the structural strength, performance, or flight characteristics of the aircraft, and that would normally require major repair or replacement of the affected component. Target Level of Safety (TLS): the degree to which safety is to be pursued in a given context, assessed with reference to an acceptable or tolerable risk. Undershoot: an event when the aircraft lands short of a run- way or planned landing spot. Veer-off: an aircraft running off the side of the runway dur- ing takeoff or landing roll. Worst Credible Condition: the most unfavorable condi- tions or combination of conditions that it is reasonable to expect will occur. 44