The Occurrence of Human Error


Since the manufacturing process is complex and consists of various systems that intricately integrate, it is prone to human error. Human errors occur from the failure to regulate systemic processes of manufacturing as stipulated, which leads to inauspicious outcomes. When manufacturing operators fail to regulate manufacturing processes according to the design of processing systems, it results in an accident or poor-quality products. Moreover, human errors occur due to the difference between the design of processing systems and how human beings think and work. Therefore, it means that the prevention of human error depends on the synchronization of processing systems and human thinking. According to Latino (2006), although human errors account for about 96% of workplace errors, they are predictable and preventable (p. 2). Proper design of processing systems and appropriate human knowledge is essential in preventing the occurrence of human errors in manufacturing industries. Common human errors in the manufacturing industry occur due to delayed judgment, deliberate actions, forgetfulness, inexperience, poor instructions, and disregard of rules amongst other factors. Moreover, processing system failures and organizational management also contribute to and complicate the occurrence of human errors in manufacturing industries. Therefore, since manufacturing system design, organizational management, and human performance complicate the occurrence of human error, identification and isolation of human error will not improve the overall performance of the system.

The Problem of System Failures and Impact of Human Error

Modern manufacturing systems are increasingly becoming complex because of the enhanced capacity and efficiency of production due to the advancement in technology.

The complexity of the manufacturing system is demanding experts with the knowledge, skills, and experiences, who can operate it effectively and prevent the occurrence of human errors. However, even though operators may minimize the occurrence of human errors, the manufacturing system has errors that are inherent in the design and manufacturing process. Manufacturing system failures and human errors cooperatively contribute to accidents or overall inefficiency of the processing system. Barroso and Wilson (2000) argue that the overall system performance depends on the reliability of manufacturing personnel and the integrity of design in manufacturing systems (p. 54). Thus, if manufacturing personnel are exceptionally reliable and accurate in their operations and manufacturing systems are stable in that they are not prone to systemic failures, then human errors will be significantly reduced. Expansion of modern manufacturing systems in terms of technology, the efficiency of processes, mass production, and high-quality production require both operating personnel and manufacturing systems, which are reliable in enhancing overall performance and reduction of both human errors and system failures. Therefore, the integrity of manufacturing systems and the reliability of operating personnel are significant factors that determine the occurrence of human errors and system failures in manufacturing industries.

The occurrence of system failures and human errors depends on the complexity of manufacturing systems. Complex manufacturing systems are more susceptible to system failures and human errors as compared to ordinary manufacturing systems. According to Cook (2000), complex manufacturing systems are inherently hazardous because they consist of multiple regulation points and require many operating personnel, hence liable to role confusion (p. 1). Multiple regulation points limit engineers and operating personnel in diagnosing minimal system failures in advance to avert the occurrence of accidents or poor manufacturing of products. Moreover, the presence of many operating personnel complicates the operation process, as there is a likelihood of interference or duplication of responsibilities, which results in both human error and subsequently system failure. It means that both system failure and human errors considerably determine the performance of a given manufacturing system.

Complex manufacturing systems demand real-time monitoring and heavy defense against failure because a slight failure at a point creates multiple failures at other points in a system, which eventually culminate into a disastrous accident. Even though human error is not responsible for system failure, it is still part of system failure because appropriate interventions are essential in the diagnosis of errors. System operating personnel need to diagnose system failures in time as part of intervention measures of avoiding human error, and take appropriate intervention to avert the impending crisis. Cook (2000) asserts that complex systems need multiple interventions against system failure, and the three of the interventions include technical, human, and organizational interventions (p. 3). Firstly, technical interventions help in the prevention of system failures and they entail constant maintenance of systems, building safety features of equipment or system, and real-time monitoring of manufacturing processes. Secondly, human interventions involve training of operating personnel to enhance their knowledge, skills, and experiences, which are critical in the prevention of human errors. Thirdly, organizational interventions play a vital role, for they provide rules, policies, and procedures that guide technical and operating personnel in the maintenance and operation of the manufacturing system. Thus, human error is a complex system functioning, human resources, and organizational management.

Even though human error is a complex system functioning, human resources, and organizational management, system failure has a considerable impact on human error. Even if the manufacturing system has competent operators, the presence of defects would consequently result in system failures and ultimately cause a disastrous accident. Since complex manufacturing systems contain several processes, maintenance personnel hardly notice latent failures within diverse processes, and this predisposes a system to subsequent failures that culminate into a disaster. Eventually, though a disaster resulted from latent systemic failure, human error becomes an apparent attribute of the disaster. Therefore, it is extraordinarily complicated to ascertain the cause of accidents in complex manufacturing systems because both system failures and human errors are significant culprits. According to Latino (2006), complex manufacturing systems operate in a mode of degradation because, despite the presence of anomalies and flaws, it continues to operate due to many redundancies that keep them going until an accident occurs (p. 3). Ultimately, due to the chain of systemic failures, it would be extremely difficult to establish whether human error contributed to the occurrence of an accident or not. Thus, systemic failures and human errors are default causes of accidents in manufacturing industries.

Human error can only be responsible for the occurrence of accidents under the assumption that manufacturing systems are intact and free from any defects or failures, which is quite impossible. Theoretically, one can assume that manufacturing systems are always free of any defects, and thus any accident that occurs is attributable to human error. Many industrial accidents are attributable to human error because human beings can detect systemic flaws and respond appropriately to prevent an accident. Generally, human actions or performance in an industry has a significant impact on determining occurrence accidents; therefore, actions or failure to act contributes to the occurrence of accidents, despite systemic failure. According to Latino (2006), human error may occur due to individual attributes and technical assessment (p. 4). Individual attributes that form part of competencies such as perception, cognitive, organization, knowledge, skills, and experiences, determine one’s preposition to human error. Moreover, technical assessment of manufacturing systems in terms of planning, execution, detection, and diagnosis of errors considerably determines the fixing of systemic failures and prevention of human errors.

Etiology of System Failures and Role of ‘Resident Pathogens’

The etiology of system failures has shown that the occurrence of system failures is due to a combination of factors that sequentially and cumulatively result in accidents or malfunctioning manufacturing systems. Although human error is one of the factors that may account for system failures, other latent factors inherent in the design of manufacturing systems are present. The latent factors are comparable to resident pathogens such as bacteria and viruses or genetic defects that physiologically interfere with the body systems of a human being. Likewise, manufacturing systems have ‘resident pathogens’ that cause latent failures that are difficult to diagnose or detect, thus resulting in human error, and causing subsequent accidents during the manufacturing process. According to Reason and Hobbs (2003), latent factors emanate from different parties involved in manufacturing systems such as designers, manufacturers, operators, and organizational managers (p. 77). Different parties give different strategic decisions in terms of formulation of policies, setting of standards, scheduling of procedures, budgeting of maintenance, and buying of complementary systems, all of which have a significant impact on the performance of manufacturing systems. Usually, latent factors, which act as ‘resident pathogens’, combine with local factors such as poor design, wrong manufacturing techniques, inexperience, lack of knowledge, poor maintenance policies, organization management, the complexity of equipment, and human errors in bringing about manufacturing system failures and accidents.

Manufacturing system design is one of the factors that contribute to the occurrence of system failure in the manufacturing industry. Poor design and wrong manufacturing techniques decrease the reliability of manufacturing systems and increase the probability of system errors occurring. Since designing and manufacturing process that involves modern technology is frightfully expensive, manufacturers tend to invest cheaply and thus compromise the integrity and quality of manufacturing systems. Karwowski and Salvendy (1994) state that, system design is the leading cause of system failures because it causes about 34% of system failures, followed by organizational factors having 31%, then human error 20%, and external factors having 15% (p. 403). This shows that system design is responsible for a greater number of industrial accidents that occur, even though it is usually an attribute of human error. Poor design of manufacturing systems results in poor operations that cause system failures and accidents. Given that experience play a critical role in minimizing human errors, poor designs have inconsistency in the application and thus interfere with the experiences and skills of operators. Ultimately, ‘resident pathogens’ of design coupled with human errors cause system failures and accidents.

Moreover, complex manufacturing systems and inexperienced operators are the cause of system failures. In an industrial environment, in many instances, due to lack of enough experience, operators misuse complex and sophisticated systems in performing basic tasks, hence generating system failures. Misuse of manufacturing systems or poor operating procedures due to inefficient experiences is one of the potential risks that predispose systems to human errors. Complex manufacturing systems have several components that are prone to failures but difficult to detect. According to Balagurusamy (1984), the complexity of manufacturing systems is not only costly to install and maintain, but also challenging to operating personnel in gaining experience (p. 6). The complexity of the manufacturing system is evident during designing and manufacturing because even designers are still grappling with system processes and how various parts coordinate. Thus, since complex manufacturing systems are prone to failures, it is advisable to use ordinary systems that are easy to operate and understand their mechanism of functioning.

Other factors that cause a system failure are poor maintenance and organizational management. Manufacturing systems cannot function indefinitely because some parts wear and tear, and thus need regular repair and maintenance. The optimal functioning of manufacturing systems depends on maintenance because it helps to eliminate failures and avert possible accidents. Even if operational personnel are experts in that they do not cause human errors, lack of proper maintenance unquestionably results in system failures. Therefore, a preventive-maintenance policy provides essential preventive measures that significantly eliminate the occurrence of system failures due to poor maintenance. Moreover, organizational management is also responsible for the occurrence of system failures. To reduce the occurrence of system failures, organizational management needs to provide an efficient system of communication and coordination so that operating personnel can share vital information regarding system failures and discuss preventive measures. Balagurusamy (1984) argues that organizational management that has rigid rules and restrictive procedures discourages creative thinking and relatively tends to experience more system failures (p. 6). Thus, organization management plays a pivotal role in creating rules, policies, procedures, and work environments that favours effective communication and coordination with a view of eliminating system failures and human errors.

Critical Analysis of Various Systemic Models of Accident Causation

The increasing complexity of manufacturing systems due to technology is posing a formidable challenge to conventional safety measures since traditional models of accident causation are no longer adequate and reliable to analyze accidents in modern socio-technical systems. Accidents in modern socio-technical systems are not attributable to system failure or human error alone because there are complex other factors that contribute to the occurrence of failures or accidents. Traditional models of accident causation were consequential models in that accidents occur due to a chain of failures and human errors that ultimately culminate into accidents. Qureshi (2007) reasons that sequential models are not adequate in elucidating causes of accidents, for they cannot comprehensively ascertain causes of accidents in modern socio-technical systems that have a complex interplay of multiple factors, which result in system failures and accidents (p. 3). Thus, new systemic models of accident causation are emerging to explain causes of accidents in complex systems, for they describe accidents as an inherent property of a whole system rather than a portion of a system as in the case of sequential models.

The system theoretic approach is one of the systemic models of accident causation. According to the system theoretic approach, the accident is a product of several factors such as human error, technical failures, and environmental factors that inadvertently contribute to the occurrence of an accident at a specific time. Since systemic models perceive accidents as a complex phenomenon of manufacturing system components, design, models, principles, and laws are essential in understanding the causation of system failures and accidents. System theoretic approach views that manufacturing systems consist of interacting components that operate in an equilibrium manner. Qureshi (2007) posits that the system theory approach considers a system as a dynamic process of interacting components rather than static design that is not adaptive to its environment (p. 4). The approach postulates that for a manufacturing system to have enhanced performance, its design needs to have constraints for safe operation and maintenance of dynamism. Thus, given the system theoretic approach of accident causation, accidents occur due to anomalies in interactions of operating personnel, engineering activities, organizational structures, software, and physical components of a system.

The cognitive system engineering approach is another model of systemic causation of system failures and accidents. Modern technology has transformed the perception of human performance from manual activities to cognitive ability in terms of knowledge, skills, and experiences. Automation of manufacturing systems has challenged conventional demands of operating personnel and created new modes of failure and accidents in manufacturing systems. The principle of the cognitive systems engineering approach is that understanding processes of manufacturing systems helps in understanding the occurrence of system failures and accidents. Hurst (1998) contends that human beings and technological systems work collectively in ensuring that manufacturing systems operate efficiently and effectively (p. 14). This implies that the synchronization of human tasks and automation of systems determines the occurrence of system failures and accidents in an industrial environment.

Accidents and system failures can also occur due to the socio-technical complexity of manufacturing systems. According to the social-technical model of systemic causation of accidents, modern manufacturing systems are highly complex and technical in that they are prone to accidents and system failures. Socio-technical systems require complex management strategies because manufacturing systems operate under enormous pressure from different factors such as competitive markets, economic constraints, legislation compliance, political forces, and social factors of operating personnel. According to Qureshi (2007), these factors have a significant impact on human behavior, work practices, and operation of complex systems, hence transforming classical perception and models of accident causation (p. 5). This model postulates that accidents and systems failures are the product of both structural and dynamic factors. Structural factors consist of hierarchical levels of management factors that determine the effectiveness of manufacturing systems. Performance and risks management of manufacturing systems are subject to laws and regulations that flow hierarchically from government, regulating bodies, organization, management, operating personnel, and procedures of work. Dynamic factors are inherent in complex environments where socio-technical systems are multifarious and integrated, for standard procedures are subjective. Given the complexity of socio-technical systems, systems dynamics need to be under the regulation of localized activities and decision-making, to prevent external interferences.

An Accident that Occurred Due to Human and Organizational Errors

Piper Alpha accident is a published example of an accident that occurred due to a combination of human errors and organizational errors. On July 6, 1988, Piper Alpha, which was an offshore platform, located in the North Sea oil field, in Britain, experienced a catastrophic fire explosion. The accident killed 167 people and damaged property worth billions of dollars. Analysis of the accident showed that it occurred due to human errors and organizational errors as well. According to Pate-Cornell (1993), the accident was predictable because system failures due to the accumulation of human errors and questionable organizational decisions were responsible (p. 215). Much blame went to the organization because its management structure, policies, procedures, and culture did not provide enough measures to mitigate system failures and subsequently prevent the occurrence of the accident.

Human errors were partly responsible for the occurrence of the Piper Alpha accident. The human errors in terms of decisions and actions affected the design, manufacturing process, maintenance, and operation of the Piper Alpha system. In terms of system design, Pate-Cornell (1993) argues that decisions of design caused three forms of couplings and dependencies; namely, the vulnerability of components to overload, susceptibility to fire propagation, and integrated failures of components (p. 224). Thus, coupling and dependencies of components made the system liable to human errors. Moreover, the design capacity of Piper Alpha was 250,000 barrels of oil per day but due to increased demand for oil products, it processed about 320,000 barrels per day. Therefore, increasing demands for oil necessitated the expansion of Piper Alpha. Expansion of the system brought new factors into play such as modification of components, hiring of more operating personnel, and maintenance of the whole system. At the time of the accident, it was evident that there were poor modifications of system components, incompetent operating personnel, and irregular maintenance of the system, all of which were cumulative human errors that resulted in system failure and caused the accident.

Additionally, organizational errors were also partly responsible for the occurrence of the Piper Alpha accident. Questionable decisions, human errors, and systems failures are attributable to the occurrence of the Piper Alpha accident. Organizational management plays a significant role in coordinating various operations of systems and consequently, their decisions and orders determine the performance of not only personnel but also the functioning of systems. For instance, organizational management determines the capacity of operating systems, modifications of components, maintenance of systems, recruitment and training of personnel. Pate-Cornell (1993) indicates that the decisions of Piper Alpha management significantly contributed to the occurrence of the accident because operating personnel overloaded the system’s capacity while the technical team made unreliable modifications of components according to instructions from management (p. 227). Moreover, the management made irregular maintenance and recruited incompetent personnel, which contributed to system failures and eventually caused the accident.


Human error is one of the causes of system failures and accidents that normally occur in an industrial environment due to the complexity of manufacturing systems. However, new research studies and systemic models of causation of accidents suggest that human error is not a discrete form of error, but exists as a complex of organizational factors and system design. Increasing automation of systems due to technology complicates operations of systems in that, it demands more knowledge, new skills, and experiences from operating personnel. The case of the Piper Alpha accident demonstrates how individual and organizational errors cumulatively result in system failure and accident. Thus, synchronization of human knowledge, organizational management, and systems mechanism of functioning is an appropriate ate approach to reducing human errors and system failures, while increasing the effectiveness, efficiency, and performance of manufacturing systems.


Balagurusamy, E., 1984. Reliability Engineering. New Delhi: Tata McGraw Hill.

Barroso, P., & Wilson, J., 2000. Human Error and Disturbance Occurrence in Manufacturing Systems (HEDOMS): A Framework and a Toolkit for Practical Analysis. Cognition, Technology & Work, 2(2), pp.51-61.

Cook, R., 2000. How Complex System Fail. Cognitive Technologies Laboratory, pp.1-5.

Hurst, N., 1998. Risk Assessment: The Human Dimension. United Kingdom: Royal Society of Chemistry.

Karwowski, W., & Salvendy, G., 1994. Organization and Management of Advanced Manufacturing. New York: Wiley & Sons Publisher.

Latino, C., 2006. Solving Human-Caused Failure Problems. Reliability Center, pp.1-5.

Pate-Cornell, E., 1993. Learning form the Piper Alpha: A Post-mortem Analysis of Technical and Organizational Factors, Risk Analysis, 13(2), pp.215-231.

Qureshi, Z., 2007. A Review of Accident Modelling Approaches for Complex Socio-Technical Systems. Australian Computer Society, pp.1-13.

Reason, J., & Hobbs, A., 2003. Managing Maintenance Error: A Practical Guide. United Kingdom: Ashgate Publishing.