System Safety Engineering: Hazard Analysis

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Table of Contents

Introduction
Background
Methods
Results
Recommendations
Conclusion
References

Introduction

A number of issues can be blamed for deteriorated system safety, including methods of construction, the procedures employed for managing safety, and conditions such as weather, as well as site-based conditions (Seo and Hyun, 2008). Harold and Moriarty note that system safety involves the application of managerial and technical skills into the system to achieve such safety (1990). The nature of hazards and severity depends with the type of the project. For instance, one of the most hazardous categories is the construction industry (Sai, Chun and Vivian, 2010). According to the authors, FMEA (Failure Modes and Effects Analysis) can be utilized in the industry for the purpose of identifying potential failure modes, and their causes and effects on the performance of the system in engineering management (Sai, Chun and Vivian, 2010). Another method that can be helpful in construction is TOPSIS for safety evaluation (Liaudanskiene, Leonas and Aleksejus, 2009) It is an approach to risk management that seeks to identify hazards, analyze them and apply remedial controls in managing them in a system based model. System based approach to a problem or weakness benefits from synergic advantage which presumes that a whole is more than the sum of its parts. As such, interaction among sub-systems, inputs, human factor and the operational environment must be based on secure integration and coexistence. Systems must be developed in ways that they risks both predictable and unforeseen can be managed in time to prevent bodily harm and loss of resources. This paper discusses the issue of hazards and how it can be analyzed. In analyzing, the paper considers the causes of hazards, the severity of them, as well as the likelihood of their occurrence.

Research Questions

What are the causes of hazards in the industry?
How can the likelihood of occurrence of and the severity of hazards be assessed and determined?

Background

Evolution of troublesome situation as a result of complex systems that are either difficult or impossible to handle by man has necessitated the application of ideologies of system safety (Rasmussen, Pejtersen, & Goodstein, 1994). It is important to make sure that there is dependability for systems so as to be able to deliver services reliably (Avizienis et al. 2004; cited in Uzunov and Thong, 2008). In addition, there is need for systems to incorporate issues of security, safety as well As be real-time in nature (Uzunov and Thong, 2008). System comprises of a number of components that work in a coordinated fashion to achieve a common identified goal. Interaction of systems components goes beyond their interaction to include its operational environment and human factor according to NASA. A system takes in demand/input process them and finally produces a desired output. In system design and development, a room is given for stresses from the environment within which the system operates. Stresses range from expected- normal to unexpected- beyond normal and system engineering must consider them during designing, development, testing and implementation stages of system life cycle. In reverse turn, system engineers must also consider the effect of system on its surrounding environment System safety helps system engineers design, analyze, learn about, control and where possible eliminate hazards in order to attain acceptable level of safety. It also aims at optimizing safety and managing residual risks. Safety as freedom from personnel injury, death caused by accidents, damages to equipment and loss of resources must consider people, equipment, facilities and time frame. The quality of the software utilized in the system will also determine the reliability of it (Musa et al. 1990; cited in Uzunov and Thong, 2008).

System safety involves studying the whole system under all operating conditions identifying, analyzing and controlling risks associated to each of the systems components plus the surrounding. Therefore, system safety cannot be claimed, if all aspects are not considered and checked out. System safety consists of analytical steps which try to identify the system through describing both physical and functional characteristics of the system using information available and observing and relating interaction among personnel, procedures, equipment and the environment, identify hazards related to all aspects of operation both titular and emergency, assess hazards to determine their consequent severity, chances of occurrence and recommend means for their control and/or riddance, resolve hazards by applying corrective measure to remove or control the hazards or assuming the risk and finally, implement a follow up analysis to verify the effectiveness of preventive measures and address upcoming and unexpected hazards and give any necessary recommendations where necessary according to NASA standards.

A system safety program also tries to identify deficiencies in a system or facility design/acquisition, modification, associated testing and operational sequences which can result in an element of risk. It maximizes operational readiness through mishap prevention measures that ensure that hazard control measures are designed and put up in the facility on time and at minimum cost. It also reduces safety and occupational health retrofit and modification requirement after the design stage. System safety ensures that occupational health lessons learnt from previously constructed similar facilities are incorporated in facility design and it ensures that modifications do not increase risk levels of a facility (FAA System Safety Handbook, 2000).

Both elements of risk hazards and their probability of occurrence must be determined in every system. Lack of historical data or inability to quantify a hazard does not prevent it from occurring. It is therefore imperative to strive to identify all possible both normal and abnormal hazards and strategize on their best counter-measures. Though some degree of hazards must be admissible, it is the role of management to determine financial allocation for control of risks in the light budget and the consequences of not implementing control measure to the said hazards. It is often difficult to determine the cost of not implementing a hazard control measure before its occurrence. However, two factors must be considered before ignoring a possible but seemingly unfeasible risk. They are; the potential consequences of their occurrence of an accident and the possibility of its occurrence (Harold, et al., 1990).

Methods

The paper relies on the review of literature, i.e. the use of secondary data in carrying out the study. Secondary sources are expected to be reliable because a lot of literature discusses hazard causes, prevention and handling. In particular, credible material from reviews and research paper can render an understanding of the subject matter.

Results

For a risk to be accepted, consequence severity must be conversely proportional to the probability of its occurrence, i.e. the more severe the consequences of an accident, the lower the probability of occurrence. As such, it would be advisable to spend money to reduce the probability of a risk by implementing hazard control. On the contrary, accidents of mild severity may be acceptable risks at higher probabilities of occurrence and will justify a lesser expenditure further reduce their frequency of occurrence.

Accident Scenario relationship

According to FAA system safety Handbook (2000), seldom does a single hazard cause an accident. One hazard could be a pre-disposing factor for another. They more these hazards are either randomly or sequentially, the more damaging the accident.

It is also imperative to look at the levels of severity in the analysis of effects. Hazards range from catastrophic to non-critical. In between, there are other levels differing on the levels of consequences and magnitude of damages. Catastrophic effects result in multiple fatalities of personnel, members of public and loss of the system (NASA Center for AeroSpace Information, 2007).

Hazardous effects pose dangers of reducing capability of the system or the ability of the operator to cope with adverse conditions to extent that there would be: large reduction in safety margin or functional capability, personnel physical distress/excessive work load such that operator cannot be relied upon to perform required tasks accurately or completely, serious fatal injuries or even death of personnel or members of public.

Minor effects do not significantly reduce system safety. There are only some slight delays, slowdowns and slight increase in workload. The last category represents no safety effects. They have no effect on the safety.

Likelihood of Occurrence

Hazards can also be classified on the basis of their probability of happening. This could be probable, remote, extremely remote and extremely probable.

Probable hazards are those anticipated to occur once or more times during the entire system/operational life of an item. Remote are unlikely to occur to each item during its total life. However, it might happen that a number of times in the life of an entire system. Again, a system may suffer problems that were not anticipated for the whole of its life (FAA system safety Handbook, 2000).

Severity of Consequence

MLT-STD-882C classifies severity of consequences as depicted below in a table.

Figure 2. Severity of consequences

Description	Category	Definition
Catastrophic		Death and/or system loss and/or severe environmental damage
Critical		Severe injury, severe occupational illness, major system and/or environmental damage
Marginal		Minor injury, minor occupational illness, minor system and/or environmental damage
Negligible		Less than Category iii description.

Recommendations

Hazards and risk are to be understood from all corners of a system. Every module must be analyzed in the light of the whole system to identify its interaction with other parts and it weakness (es) which could be contagious, affecting the safety of the whole system.
Risks/hazards must not be ignored merely because they have never been experienced in previous or current system(s). Probability of occurrence and cost of consequence must always guide system safety strategy. Lack of hazards strikes and historical data should not limit preparedness for the same.
An accident more often than not is caused by a string of hazards, some predisposing others. Related hazards must be identified and managed as such.
Hazards analysis is an ongoing process. It must be periodically carried out. Retrofitting and system redesigning sometimes compromise system safety. A hazard monitoring and assessment plan must be put in place to cater for such changes and ensure they comply with system safety requirements.
Hazards must also be considered in terms of impact of the system to its operational environment. The impact must be categorized the same way as other common hazards.
Hazards must be thought of beginning as early as during system design and testing. It allows for identification, classification and management of hazards in time and accordingly.

Conclusion

System safety concerns identification and preparedness to optimize safety of a system. Identification of factors which could cause anything less than safety is a hazard. System safety will be assured if the aspects of likelihood, severity and causes of occurrence of hazards are settled. Hazards analysis seeks to identify hazards and classify them according to their impact and consequences. It is a more comprehensive risk management technique that tries to control and eliminate hazards before the strike. It depicts organizations seriousness and preparedness to counter system attack forces in time and cost effective manner.

References

Avizienis, A., Laprie, J., Randell, B., and Landwehr, C. (2004). Basic Concepts and Taxonomy of Dependable and Secure Computing. IEEE (Trans). Dependable and Secure Computing, 1, 1, 11-33.

FAA System Safety Handbook. (2000). Post-Investment Decision Safety Activities. FAA System Safety Handbook. Web.

Harold, R., and Brian, M. (1990). System Safety Engineering and Management. New Jersey: John Wiley & Sons.

Liaudanskiene, R., Leonas, U., and Aleksejus, B. (2009). Evaluation of construction process safety solutions using the TOPSIS methods. Inzinerine Ekonomika-Engineering Economics, 4, 32-40.

Musa, J., Iannino, A., and Okumoto, K. (1990). Software Reliability -Measurement, Prediction, Application. McGraw-Hill Publishing. p. 291.

NASA Center for AeroSpace Information. (2007). Preliminary Considerations for Classifying Hazards of Unmanned Aircraft Systems. NASA Center for AeroSpace Information.

Rasmussen, J., Pejtersen, M., Goodstein, L., et al. (1994). Cognitive Systems Engineering. New York: Wiley.

Sai, Z., Chun, T., and Vivian, T. (2010). Integrating safety, environmental and quality risks for project management using a FMEA method. Inzinerine Ekonomika-Engineering Economics, 21, 1.

Seo, J., and Hyun, C. (2008). Risk-based safety impact assessment methodology for underground construction projects in Korea. Journal of Construction Engineering and Management, 72-81.

Uzunov and Thong. (2008). Dependability of software in airbone mission systems. Web.

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