System safety concepts generally

As a primer. Standard Practice for System Safety, 882-D, Department of Defense. General system safety concepts and program requirements are set forth. 

A collection of philosophical statements and general advice relative to the application of the MORT system safety concepts and listed criteria for an assessment of the effectiveness of their application... 

It has been suggested here that this basic system safety concept is in direct correlation with the stated intentions of the Occupational Safety and Health Act, as established by the General Duty Clause. In many cases, then, system safety cannot... 

Though this might appear as almost a laundry list of system safety concepts, they do ht well into a cogent unit as PSM plan, the same type of elements described in the system safety program plan and in general in a good SMS as described in Chapter 4. 

Mil STD-882B (11) outlines the general concepts of Systems Safety. Notice 1 (12) appended to that document specifically covers requirements for software systems safety. The Air Force also has a Software Systems Safety Handbook (13). A number of recent articles in Hazafd Prevention (14), the Journal of the Systems Safety Society, expanded on the technical content of this handbook. The concepts were covered in a more explicit and useful manner by Erwin Schoitsch of the Austrian Research Center Seibersdorf in a recent forty-two page, two-part, article (15). 

My first book, Safeware, presents a broad overview of what is known and practiced in System Safety today and provides a reference for understanding the state of the art. To avoid redundancy, information about basic concepts in safety engineering that appear in Safeware is not, in general, repeated. To make this book coherent in itself, however, there is some repetition, particularly on topics for which my understanding has advanced since writing Safeware. 

Very little real analysis is completed during the concept phase because analysis detail and data are generally not available. A preliminary risk assessment code (RAC) is determined, however, as part of the preliminary hazard list. This initial RAC is used to aid in determining the initial scope of the system safety effort and in the early evaluation of alternative designs and approaches. 

In addition to updated content of the first edition, the revised second edition of the Basic Guide to System Safety has a more expanded and useful glossary of terms it also contains a new chapter describing the basic concept, utility, and function of the hazard and operability study (HAZOP) and what-if analysis. Both of these analytical techniques have been used quite routinely and successfully in the petrochemical industry for decades. As with all analytical methods and techniques presented in this text, it is suggested that the HAZOP smdy and what-if analysis have definite application to general industry operations as well. 

Which general targets could be formulated for a safety concept. ISO 26262 clearly defined that the functional and technical safety concept should be defined derived from the ITEM Definition, a system on vehicle level and the resulting safety goals from the Hazard and Risk Analysis. 

Also in this context a detailed analysis of the target function and the required safety measurements is necessary in order to avoid an overall generalized safeguarding. Almost all error modes could be the possible cause of failure for safety relevant effects. To safeguard the computer just like programmable l( c control (PLCs) would not be appropriate. This is why a safety concept isn t only useful in regards to the vehicle systems but also for function or system elements, which later have to be integrated in the vehicle system. 

Two objectives are defined for safety validation the first is the evidence that the safety goals are considered adequately in the context of the functional safety concept and the defined item. The second objective asks for the evidence that the safety goals themselves are correct and achieved on vehicle level. The hope of any safety validation is, to proof that the vehicle is safe as such, hut ISO 26262 could provide support on the evidence of functional safety for E/E-Systems. The safety-live-cycle in ISO 26262, part 2 shows, that external measures and also measures of other technology have to be considered during safety validation. In 9.2 General the relation to other activities are detailed. 

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