|
Conventional systems engineering methodologies do not provide guidance on how to reduce the risks of unexpected events. The term unexpected event has recently been coined, to stress the need to design systems to handle unexpected situations.〔(), Mitigating the Risks of Unexpected Events by Systems Engineering〕 This Wikipedia entry summarizes the contribution made by several scientists and methodologists (notably, Hollnagel,〔(), Hollnagel: Why "Human Error" is a Meaningless Concept〕 (Casey ),〔(), Casey: Set Phasers on Stun〕 (Reason ),〔(), Reason: Managing the Risks of Organizational Accidents〕 (Dekker )〔(), Dekker: The Field Guide to Understanding Human Error〕 and Leveson〔(), Nancy Leveson home page〕), who specialize in human errors, to express their view that unexpected events should not be attributed to the person who happened to be there at the time of the mishap, and that they should not be regarded as force majeure. A better approach, which may help mitigating the risks of unexpected events, is by considering the human limited capability to coordinate with the system during the interaction.〔 ==Definition== An unexpected event is a normal event, arriving in an exceptional situation, with costly results: productivity loss,〔(), Thomas K. Landauer (1996): The Trouble with Computers: Usefulness, Usability, and Productivity〕 reduced customer satisfaction〔(), A. Harel, R. Kennett and F. Ruggeri (2008) - Modeling Web Usability Diagnostics on the basis of Usage Statistics, in: Statistical Methods in eCommerce Research, W. Jank and G. Shmueli editors, Wiley.〕 and accidents.〔(), Sheridan & Nadler, (2006): Review of Human-Automation Interaction Failures and Lessons Learned (Report No. DOT-VNTSC-NASA-06-01)〕 In practice, systems cannot always meet all the expectations of its stakeholder. * The number of all possible system states is too large to handle at design time * The expectations are based on partial knowledge of the design * The way the system is being operated changes with time, introducing new exceptional situations. Well known examples of accidents due to unexpected events include: * Aviation accidents and incidents * Lists of rail accidents * Nuclear and radiation accidents Easy-to-read examples of unfortunate unexpected events are described in (Casey )'s book "Set Phasers on Stun".〔(), Steven Casey (1993). Set Phasers on Stun, And Other True Tales of Design, Technology and Human Error, Aegean Publishing.〕 A comprehensive list of accidents may be found in this list. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Unexpected events」の詳細全文を読む スポンサード リンク
|