A critical fault endang or a few people a

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suffering from a “command fault”. A “critical” fault endangers one or a few people. A “catastrophic fault” endangers, harms or kills a significant number of people. Activity Prepare a report on safety engineering in case of airplanes. (c) UPES, Not for Reproduction/ Sale
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Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ Aviation Safety & Security Management Safety engineers also identify different modes of safe operation: A “probabilistically safe” system has no single point of failure, and enough redundant sensors, computers and effectors so that it is very unlikely to cause harm (usually “very unlikely” means, on average, less than one human life lost in a billion hours of operation). An inherently safe system is a clever mechanical arrangement that cannot be made to cause harm – obviously the best arrangement, but this is not always possible. A fail-safe system is one that cannot cause harm when it fails. A “fault- tolerant” system can continue to operate with faults, though its operation may be degraded in some fashion. These terms combine to describe the safety needed by systems: For example, most biomedical equipment is only “critical”, and often another identical piece of equipment is nearby, so it can be merely “probabilistically fail-safe”. Train signals can cause “catastrophic” accidents (imagine chemical releases from tank-cars) and are usually “inherently safe”. Aircraft “failures” are “catastrophic”, so aircraft are usually “probabilistically fault-tolerant”. Without any safety features, nuclear reactors might have “catastrophic failures”, so real nuclear reactors are required to be at least “probabilistically fail-safe”. The Process Ideally, safety-engineers take an early design of a system, analyze it to find what faults can occur, and then propose safety requirements in design specifications up front and changes to existing systems to make the system safer. In an early design stage, often a fail-safe system can be made acceptably safe with a few sensors and some software to read them. Probabilistic fault- tolerant systems can often be made by using more, but smaller and less-expensive pieces of equipment. Far too often, rather than actually influencing the design, safety engineers are assigned to prove that an existing, completed design is safe. If a safety engineer then discovers significant safety problems late in the design process, correcting them can be very expensive. This type of error has the potential to waste large sums of money. The exception to this conventional approach is the way some large government agencies approach safety engineering from a more proactive and proven process perspective. This is known as System (c) UPES, Not for Reproduction/ Sale
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UNIT 17: Reliability Fundamental Theories Notes ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________ Safety. The System Safety philosophy, supported by the System Safety Society, is to be applied to complex and critical systems, such as commercial airliners, military aircraft, munitions and complex weapon systems, spacecraft and space systems, rail and transportation systems, air traffic control system and more complex and safety-critical industrial systems. The proven System
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  • Fall '19
  • Instrument approach, Runway, Rajiv, Aviation Safety & Security Management

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