Qualitative safety objectives

Apply the worst-case flight phases to the functional failure mode in column 4 of Table 3.6 and allocate qualitative safety objectives (Table 3.2) in column 9 (i.e. minimum probability of occurrence) to each failure condition based on the worst potential consequence of the failure. 

All failure modes are classified according to their severity (e.g. minor, major, hazardous and catastrophic) depending an the safety criteria chosen. Each failure mode classification is allocated a numerical or a qualitative safety objective, which is agreed with the applicable airworthiness authority. 

In accordance with the applicable safety criteria, each failure mode classification can now be allocated a quantitative and/or a qualitative safety target based on its level of criticality. Table 3.3 shows the safety criteria typically used for large civil transport aircraft. These safety targets will then become a design objective (or safety goal) for the system architects to achieve. 

NFPA has developed a Fire Safety Concepts Tree At the top of the tree are fire safety objectives, followed by actions to achieve the objectives. Elements of the tree connect using AND and OR gates, similar to fault tree analysis (Figure 36-10). A Fire Safety Concepts Tree can help analyze buildings and designs using qualitative and quantitative procedures. 

Safety objectives are fixed for every nuclear installation. These objectives should be measurable, both qualitatively and quantitatively, and they should include prevention of severe accidents and mitigation of the consequences, should prevention fail, as it has been clearly stated in a series of IAEA INSAG reports. When setting safety objectives, other factors (notably non-fatal health effects) should also be taken into account, as learned from the historical severe accidents. 

There are usirally several safety objectives, which are set in consideration of the possible conseqnences of considered events (e g. 10 and 10 per launch for damage to people and facihties, respectively, under the rules applicable to the Giriana Space Center). To these quantitative objectives are added qualitative reqirirements on the nnmber of tolerated faults (2 and 1, respectively). 

Determining the safety requirements (i.e. qualitative and/or quantitative safety objectives commensurate with the particular hazard), starting with the appropriate system level and flowing those requirements down to the required sub-system/ unit/component level. This is the purpose of the PSSAs. 

Ideally the design (i.e. the selection of components, the system architecture and the means of integration) should now be implemented in such a way as to ensure that the safety objectives are accomplished. The best route(s) to achieving the objectives must be chosen. Qualitative objectives and constraints will come into play here through the influence of the different stakeholders (especially the decision-makers who control the purse strings). A trade-off may be required in terms of a cost-benefit-analysis to ensure that certain hazards are indeed ALARP. 

Occasionally the qualitative and intuitive methods of risk assessment fail, and something better is required. For example, a designer may have taken steps to address some hazard, but be unsure whether these are sufficient. There is also the possibility of failure of equipment, control systems or operating procedures which may reduce margins of safety. In these circumstances, quantitative risk assessment may be considered. This is an attempt to put numbers to the risks so that we can judge them objectively. 

ABSTRACT With Analytic Hierarchy Process (AHP), this paper sorts hierarchically various index on the impact of tender invitation and evaluation for mine safety equipments and forms an orderly hierarchical structure. By means of calculation, its weight is determined. Then a objective and scientific evaluation system of bid scheme is established with the combination of quantitative evaluation and qualitative evaluation, which reduces the influence of subjective elements and reflects an open, fair and just principle of competition. 

The investigation has shown how the safety of the system can be improved. At the same time its availability is increased, although this was not the express objective of the analysis. Some of the results were already obtained in the qualitative part of the analysis. The quantification of the fault trees brought further insights and enabled one to identify areas of unbalanced safety measures. The latter are characterized by largely differing contributions of an individual initiating event to the expected frequency of an explosion (vid. Table 9.48). The proposals for... 

The domino effect is introduced into the safety assessment of tank area we do qualitative and quantitative evaluation of interaction between the evaluation units. Determine the likelihood of secondary accidents and accident losses. Safety evaluation of Domino effect is more focused on analyses the interactions between units, as well as the additive effects of the consequences of the accident. It is a more objective method of safety evaluation. 

Methods, criteria, and analysis What management methods and techniques were employed to ensure that safety programs and policies were implemented (management/safety by objectives, for example) Were these methods adequate What criteria were used to evaluate the effectiveness of implementation What types of qualitative or quantitative analyses were done to determine the effectiveness of safety program implementation Were they adequate ... 

Qualitative performance measurements, such as checklists, are commonly used to assess the status of safety and health programs. Quantitative, or objective, performance measurements are necessary for precision, consistency, and reproducibility. 

NOTE 2 The safety integrity level is defined numerically so as to provide an objective target to compare alternative designs and solutions. However, it is recognized that, given the current state of knowledge, many systematic causes of failure can only be assessed qualitatively. 

The costs are then balanced against the benefits (both qualitative and quantitative) and then an objective decision may be made on whether to allocate resources to the project or not. This will usually be based on the length of the pay-back period. Most health and safety projects will generally have a pay-back period of between three and five years - i.e. medium-term rather than short-term. 

The objective of human factors safety analysis is to identify and correct human error situations that could lead to significant hazards. The analysis can be either qualitative or quantitative, depending on the level of detail desired and what the consequences are of a person making a mistake. The steps of a human factors safety analysis are as follows ... 

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