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OCR for page 43
43 Definitions Acceptable Level of Risk: likelihood of an event when proba- ple fatalities; or there was one fatality and the airplane was bility of occurrence is small, whose consequences are so slight, substantially damaged. or whose benefits (perceived or real) are so great, that individ- METAR: aviation routine weather report. uals or groups in society are willing to take or be subjected to the risk that the event might occur. Nonconformity: non-fulfillment of a requirement. This in- cludes but is not limited to non-compliance with Federal reg- Accident: an unplanned event or series of events that re- ulations. It also includes an organization's requirements, sults in death, injury, or damage to, or loss of, equipment or policies, and procedures, as well as requirements of safety risk property. controls developed by the organization. Consequence: the direct effect of an event, incident, or acci- Overrun or Overshoot: a departure of the aircraft from the dent. In this study it is expressed as a health effect (e.g., death, end of the intended landing runway surface. injury, exposure) or property loss. Quantitative Risk Analysis: incorporates numerical esti- Fatal Injury: any injury that results in death within 30 days of mates of frequency or probability and consequence. the accident. Risk: the combination of the likelihood and the consequence Hazard: the inherent characteristic of a material, condition, of a specified hazard being realized. It is a measure of harm or or activity that has the potential to cause harm to people, loss associated with an activity. property, or the environment. Risk Analysis: the study of risk in order to understand and Hazard Analysis: the identification of system elements, events quantify risk so it can be managed. or material properties that lead to harm or loss. Hazard analy- sis may also include evaluation of consequences from an event Risk Assessment: determination of risk context and accept- or incident. ability, often by comparison to similar risks. Hull Loss: airplane totally destroyed or damaged and not Runway Criticality: term introduced in this study to repre- repaired. sent the relationship between the runway distance required by a given aircraft and specific operational conditions, and the Incident: a near miss episode, malfunction, or failure with- runway distance available for that operation (landing or take- out accident-level consequences that has a significant chance off). Runway criticality is represented mathematically by the of resulting in accident-level consequences. ratio between the runway distance required and the runway Likelihood: expressed as either a frequency or a probability. distance available. A higher ratio means a lower safety margin Frequency is a measure of the rate at which events occur over and greater operation criticality. time (e.g., events/year, incidents/year, deaths/year). Probabil- Safety: absence of risk. Safety often is equated with meeting a ity is a measure of the rate of a possible event expressed as a measurable goal, such as an accident rate that is less than fraction of the total number of events (e.g., one-in-ten-million, an acceptable target. However, the absence of accidents does 1/10,000,000, or 1 10-7). not ensure a safe system. To remain vigilant regarding safety, it Major Accident: an accident in which any of three condi- is necessary to recognize that just because an accident has not tions is met: the airplane was destroyed; or there were multi- happened, it does not mean that it cannot or will not happen.

OCR for page 43
44 Safety Management System: the formal, top-down business- of the aircraft, and that would normally require major repair like approach to managing safety risk. It includes systematic or replacement of the affected component. procedures, practices, and policies for the management of Target Level of Safety (TLS): the degree to which safety is to safety (including safety risk management, safety policy, safety be pursued in a given context, assessed with reference to an assurance, and safety promotion). acceptable or tolerable risk. Safety Risk Management: the systematic application of poli- Undershoot: an event when the aircraft lands short of a run- cies, practices, and resources to the assessment and control of way or planned landing spot. risk affecting human health and safety and the environment. Hazard, risk, and cost/benefit analysis are used to support de- Veer-off: an aircraft running off the side of the runway dur- velopment of risk reduction options, program objectives, and ing takeoff or landing roll. prioritization of issues and resources. Worst Credible Condition: the most unfavorable condi- Substantial Damage: damage or failure that adversely affects tions or combination of conditions that it is reasonable to the structural strength, performance, or flight characteristics expect will occur.