System safety
Encyclopedia
The system safety concept calls for a risk management
strategy
based on identification, analysis of hazards and application of remedial controls using a systems-based approach. This is different from traditional safety strategies which rely on control of conditions and causes of an accident based either on the Epidemiological
analysis or as a result of investigation of individual past accidents.. The concept of system safety is useful in demonstrating adequacy of technologies when difficulties are faced with probabilistic risk analysis
. The underlying principle is one of synergy
: a whole is more than sum of its parts. Systems-based approach to safety
requires the application of scientific, technical and managerial skills to hazard identification, hazard analysis
, and elimination, control, or management of hazards throughout the life-cycle of a system, program, project or an activity or a product. "Hazop
" is one of several techniques available for identification of hazards.
is defined as a set or group of interacting, interrelated or interdependent elements or parts that are organized and integrated to form a collective unity or a unified whole to achieve a common objective. This definition lays emphasis on the interactions between the parts of a system and the external environment to perform a specific task or function in the context of an operational environment. This focus on interactions is to take a view on the expected or unexpected demands (inputs) that will be placed on the system and see whether necessary and sufficient resources are available to process the demands. These might take form of stresses. These stresses can be either expected, as part of normal operations, or unexpected, as part of unforeseen acts or conditions that produce beyond-normal (i.e., abnormal) stresses. This definition of a system, therefore, includes not only the product or the process but also the influences that the surrounding environment (including human interactions) may have on the product’s or process’s safety performance. Conversely, system safety also takes into account the effects of the system on its surrounding environment. Thus, a correct definition and management of interfaces becomes very important. Broader definitions of a system are the hardware, software, human systems integration, procedures and training. Therefore system safety as part of the systems engineering process should systematically address all of these domains and areas in engineering and operations in a concerted fashion to prevent, eliminate and control hazards.
A “system", therefore, has implicit as well as explicit definition of boundaries to which the systematic process of hazard identification, hazard analysis and control is applied. The system can range in complexity from a manned spacecraft to an autonomous machine tool. The system safety concept helps the system designer(s) to model, analyse, gain awareness about, understand and eliminate the hazards, and apply controls to achieve an acceptable level of safety. Ineffective decision making
in safety matters is regarded as the first step in the sequence of hazardous flow of events in the "Swiss Cheese" model
of accident causation. Communications regarding system risk have an important role to play in correcting risk perceptions by creating, analysing and understanding information model to show what factors create and control the hazardous process. For almost any system, product, or service, the most effective means of limiting product liability and accident risks is to implement an organized system safety function, beginning in the conceptual design phase and continuing through to its development, fabrication, testing, production, use and ultimate disposal. The aim of the system safety concept is to gain assurance that a system and associated functionality behaves in a safe manner and is safe to operate. This assurance is necessary. Technological advances in the past have produced positive as well as negative effects.
describes some of the methods used in nuclear and other industries. Traditional safety engineering techniques are focused on the consequences of human error and do not investigate the causes or reasons for the occurrence of human error. System safety concept can be applied to this traditional field to help identify the set of conditions for safe operation of the system. Modern and more complex systems with computer application and controls require functional hazard analyses and a set of detailed specifications at all levels that address safety attributes to be inherent in the design.
is an important application of the system safety field, due to the potentially destructive effects of a system failure or malfunction. A healthy skeptical attitude towards the system, when it is at the requirements definition and drawing-board stage, by conducting functional hazard analyses, would help in learning about the factors that create hazards and mitigations that control the hazards. A rigorous process is usually formally implemented as part of systems engineering to influence the design and improve the situation before the errors and faults weaken the system defences and cause accidents.
Typically weapons systems pertaining to ship
s, land vehicles, guided missile
s and aircraft
differ in hazards and effects; some are inherent, such as explosives, and some are created due to the specific operating environments (as in, for example, aircraft sustaining flight). In the military aircraft industry safety-critical functions are identified and the overall design architecture of hardware, software and human systems integration are thoroughly analyzed and explicit safety requirements are derived and specified during proven hazard analysis process to establish safeguards to ensure essential functions are not lost or function correctly in a predictable manner. Prevention of mishaps is the objective.
Risk management
Risk management is the identification, assessment, and prioritization of risks followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events or to maximize the realization of opportunities...
strategy
Strategy
Strategy, a word of military origin, refers to a plan of action designed to achieve a particular goal. In military usage strategy is distinct from tactics, which are concerned with the conduct of an engagement, while strategy is concerned with how different engagements are linked...
based on identification, analysis of hazards and application of remedial controls using a systems-based approach. This is different from traditional safety strategies which rely on control of conditions and causes of an accident based either on the Epidemiological
Epidemiology
Epidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
analysis or as a result of investigation of individual past accidents.. The concept of system safety is useful in demonstrating adequacy of technologies when difficulties are faced with probabilistic risk analysis
Risk analysis (engineering)
Risk analysis is the science of risks and their probability and evaluation.Probabilistic risk assessment is one analysis strategy usually employed in science and engineering.-Risk analysis and the risk workshop:...
. The underlying principle is one of synergy
Synergy
Synergy may be defined as two or more things functioning together to produce a result not independently obtainable.The term synergy comes from the Greek word from , , meaning "working together".-Definitions and usages:...
: a whole is more than sum of its parts. Systems-based approach to safety
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
requires the application of scientific, technical and managerial skills to hazard identification, hazard analysis
Hazard analysis
A hazard analysis is used as the first step in a process used to assess risk. The result of a hazard analysis is the identification of risks. Preliminary risk levels can be provided in the hazard analysis. The validation, more precise prediction and acceptance of risk is determined in the Risk...
, and elimination, control, or management of hazards throughout the life-cycle of a system, program, project or an activity or a product. "Hazop
Hazop
A hazard and operability study is a structured and systematic examination of a planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment, or prevent efficientoperation....
" is one of several techniques available for identification of hazards.
System approach
A systemSystem
System is a set of interacting or interdependent components forming an integrated whole....
is defined as a set or group of interacting, interrelated or interdependent elements or parts that are organized and integrated to form a collective unity or a unified whole to achieve a common objective. This definition lays emphasis on the interactions between the parts of a system and the external environment to perform a specific task or function in the context of an operational environment. This focus on interactions is to take a view on the expected or unexpected demands (inputs) that will be placed on the system and see whether necessary and sufficient resources are available to process the demands. These might take form of stresses. These stresses can be either expected, as part of normal operations, or unexpected, as part of unforeseen acts or conditions that produce beyond-normal (i.e., abnormal) stresses. This definition of a system, therefore, includes not only the product or the process but also the influences that the surrounding environment (including human interactions) may have on the product’s or process’s safety performance. Conversely, system safety also takes into account the effects of the system on its surrounding environment. Thus, a correct definition and management of interfaces becomes very important. Broader definitions of a system are the hardware, software, human systems integration, procedures and training. Therefore system safety as part of the systems engineering process should systematically address all of these domains and areas in engineering and operations in a concerted fashion to prevent, eliminate and control hazards.
A “system", therefore, has implicit as well as explicit definition of boundaries to which the systematic process of hazard identification, hazard analysis and control is applied. The system can range in complexity from a manned spacecraft to an autonomous machine tool. The system safety concept helps the system designer(s) to model, analyse, gain awareness about, understand and eliminate the hazards, and apply controls to achieve an acceptable level of safety. Ineffective decision making
Decision making
Decision making can be regarded as the mental processes resulting in the selection of a course of action among several alternative scenarios. Every decision making process produces a final choice. The output can be an action or an opinion of choice.- Overview :Human performance in decision terms...
in safety matters is regarded as the first step in the sequence of hazardous flow of events in the "Swiss Cheese" model
Swiss Cheese model
Models of accident causation are used for the risk analysis and risk management of human systems. Since the 1990s they have gained widespread acceptance and use in healthcare, in the aviation safety industry, and in emergency service organizations...
of accident causation. Communications regarding system risk have an important role to play in correcting risk perceptions by creating, analysing and understanding information model to show what factors create and control the hazardous process. For almost any system, product, or service, the most effective means of limiting product liability and accident risks is to implement an organized system safety function, beginning in the conceptual design phase and continuing through to its development, fabrication, testing, production, use and ultimate disposal. The aim of the system safety concept is to gain assurance that a system and associated functionality behaves in a safe manner and is safe to operate. This assurance is necessary. Technological advances in the past have produced positive as well as negative effects.
Root cause analysis
A root cause analysis identifies the set of multiple causes that together might create a potential accident. Root cause techniques have been successfully borrowed from other disciplines and adapted to meet the needs of the system safety concept, most notably the tree structure from Fault Tree Analysis, which was originally an engineering technique. The root cause analysis techniques can be categorised into two groups: a) tree techniques, and b) check list methods. There are several root causal analysis techniques, e.g. Management Oversight and Risk Tree (MORT) analysis. Others are Event and Causal Factor Analysis (ECFA),Multilinear Events Sequencing, Sequentially Timed Events Plotting Procedure, Savannah River Plant Root Cause Analysis System.Safety engineering
Safety engineeringSafety engineering
Safety engineering is an applied science strongly related to systems engineering / industrial engineering and the subset System Safety Engineering...
describes some of the methods used in nuclear and other industries. Traditional safety engineering techniques are focused on the consequences of human error and do not investigate the causes or reasons for the occurrence of human error. System safety concept can be applied to this traditional field to help identify the set of conditions for safe operation of the system. Modern and more complex systems with computer application and controls require functional hazard analyses and a set of detailed specifications at all levels that address safety attributes to be inherent in the design.
Weapon system safety
Weapon System SafetyWeapon System Safety
The United States Navy formed the Weapon System Explosives Safety Review Board in 1968 as a result of the tragic fire on the USS Forrestal . The subsequent investigation recommended an independent review process be established...
is an important application of the system safety field, due to the potentially destructive effects of a system failure or malfunction. A healthy skeptical attitude towards the system, when it is at the requirements definition and drawing-board stage, by conducting functional hazard analyses, would help in learning about the factors that create hazards and mitigations that control the hazards. A rigorous process is usually formally implemented as part of systems engineering to influence the design and improve the situation before the errors and faults weaken the system defences and cause accidents.
Typically weapons systems pertaining to ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
s, land vehicles, guided missile
Guided Missile
Guided Missile is a London based independent record label set up by Paul Kearney in 1994.Guided Missile has always focused on 'the underground', preferring to put out a steady flow of releases and developing the numerous GM events around London and beyond....
s and aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
differ in hazards and effects; some are inherent, such as explosives, and some are created due to the specific operating environments (as in, for example, aircraft sustaining flight). In the military aircraft industry safety-critical functions are identified and the overall design architecture of hardware, software and human systems integration are thoroughly analyzed and explicit safety requirements are derived and specified during proven hazard analysis process to establish safeguards to ensure essential functions are not lost or function correctly in a predictable manner. Prevention of mishaps is the objective.