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An Introduction to Tools and Techniques
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This table summarises some of the Safety Assessment Tools and Techniques available to the safety assessor. Each of these tools has its own advantages and disadvantages and the extent to which these can be used during various phases of the product lifecycle, and the degree to which they can be applied to safety assessments, vary. For a list of Advantages and Limitations of each, see Appendix A to Aircraft System Safety: Military and Civil Aeronautical Applications.
It is extremely important to note that as the complexity of the tool increases so does the degree of training required for the user and/or the need for an experienced evaluation team to conduct the evaluation. On the plus side, the data derived from the more complex methodologies may be more supportable. Unfortunately, the primary disadvantage of such tools is that "trained subject matter experts" may have limited experience in the actual operational environment and, therefore, their evaluations may not be entirely applicable to the certification process.
To hide this text and give you more room to view the table of tools and techniques, click the "minus" sign symbol at the top right of the container surrounding this introduction.
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Tools and Techniques
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| | Name | Description |
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| Integrated Performance Modelling Environment (IPME) | IPME is a Unix/Silicon Graphics based software tool providing a suite of tools to aid human factors practitioner in understanding human-system performance. IPME incorporates mission analysis, function analysis, function allocation, task analysis, and workload/performance analysis and prediction. It is a tool that does require training in the use of the tool and can be time consuming to use in complex models [Dahn et al, 1997]
See Eurocontrol. |
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| Interface Analysis | The analysis is used to identify hazards due to interface incompatibilities. The methodology entails seeking those physical and functional incompatibilities between adjacent, interconnected, or interacting elements of a system which, if allowed to persist under all conditions of operation, would generate risks. Interface Analysis is applicable to all systems. All interfaces should be investigated; machine-software, environment, human,environment-machine, human-human, machine-machine, etc. [Tarrents, 1980] |
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| Ishikawa Diagrams | Also called Cause-and-Effect or Fishbone diagram. Problem of interest (e.g. haz or accident) is entered at end of main "bone". All possible causes are then "fleshed out".
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| Job Safety Analysis | This technique is used to assess the various ways a task may be performed so that the most efficient and appropriate way to do a task is selected. Job Safety Analysis can be applied to evaluate any job, task, human function, or operation. Each job is broken down into tasks, or steps, and hazards associated with each task or step are identifies. Controls are then defined to decrease the risk associated with the particular hazards. [Tarrents, 1980] |
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| Justification of Human Error Data Information (JHEDI) | JHEDI is derived from the Human Reliability Management System (HMRS) and is a quick form of human reliability analysis that requires little training to apply. The tool consists of a scenario description, task analysis, human error identification, a quantification process, and performance shaping factors and assumptions. JEDHI is a moderate, flexible and auditable tool for use in human reliability analysis. Some expert knowledge of the system under scrutiny is required [Kirwan, 1994]
See Eurocontrol. |
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| Key Issues Tool (KIT) | KIT is a software tool designed to support the EHFA (Early Human Factors Analysis). It makes the EHFA process easier by providing structure and supporting the difficult aspects of tracking and linking many items. The output from KIT acts as an input to a project's overall risk register, allowing the project manager to see the human factors integration (HFI) risks in a manner which is comparable to other areas of project risk. The tool provides a full record of the analysis conducted on any issue over the life of a project [McLeod and Walters, 1999].
See Nickleby HFE Ltd and Eurocontrol. |
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| Laser Safety Analysis | This analysis enables the evaluation of the use of Lasers from a safety view. The analysis is appropriate for any laser operation, i.e. construction, experimentation, and testing. [Tarrents, 1980] |
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| Layer of Protection Analysis (LOPA) | Used for SIL determination. Is a relatively new method, developed by the American Institute of Chemical Engineers (CCPS) group in response to the requirements of ISA S84.01 and was formally published in 2001. It effectively combines a number of different techniques into a composite method that is well tailored to assessing process risks and development of hazardous scenarios.
As indicated by its name, it involves assessing layers of protection other than just the instrument protective functions. For instance, a contribution toward risk reduction by Independent Protective Layers (IPLs) such as 'alarms and operators' or 'basic process control' is explicitly defined as a risk reduction factor. The combination of the risk reduction factors for all IPLs provides the total risk reduction possible. It is fundamentally a simplified quantitative method that considers the risk reduction contributed from each IPL typically by order of magnitude risk reduction (i.e., say 0.1 for a DCS, or 0.01 for a relief valve, etc).
[Kirkwoodm D, Current issues with SIL assessment methods, Functional Safety Professional Network, Technical Advisory Panel, david.kirkwood@rtel.com] |
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| Life Data Analysis | See Weibull Analysis. |
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| Maintenance Error Decision Aid (MEDA) | Boeing has invested decades of research in maintenance error. It has developed a widely used maintenance error decision aid (MEDA) which is an attempt to systematise evaluation of events, problems and potential problems by using a repeatable, structured evaluation program. The company has been encouraging its customers to employ the technique [Allen and Rankin, 1996]
See Boeing Commerical Aero Magazine |
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