Human Error in Operator Decision-Making


Human error in operator decision-making often results to tragic events and industrial accidents. In particular, in aviation, human error has far-reaching implications on the safety of the passengers and the pilot as well. Hence, an effort to design better computer systems to reduce human error and make the aviation industry safer is essential. The lack of accuracy and precision by operators when handling industrial machine is often the cause of most industrial accidents. Although humans may be flexible, adaptable and creative, the lack of continual alertness and accuracy in action or memory result to errors. Naturally, humans have a tendency to interpret information partially, which often cause operators to misinterpret certain aspects of the system resulting to errors.

In industry, human errors are inevitable even with the best training and thus, human error reduction techniques and proper situational awareness are important in addressing human error especially in aviation. In fact, most of the causal factors of industrial accidents arise from a combination of human errors. Technically, operator error may arise from poorly designed equipment, mistakes during operation of the systems or inadequate supervision or training of the workers. Operator errors may arise from inappropriate human behavior during an industrial process, which influences the effectiveness or safety of the system and contributes to accidents or injury (Wickens, Gordon, & Liu 1998, p. 76). In general, however, human factors such as design of industrial equipment, the physical environment and the nature of the work contribute to operator error. Although previous experience may be useful in reducing operator errors, in novel situations, operator knowledge base is essential in analytical processing of the situation. Operator error and their adverse consequences can be reduced through training and proper system design.

Operator Errors and Industrial Accidents

Most industrial accidents arise from operator error when operating industrial systems. However, Pereira Lima argues that human error does not always contribute to industrial accidents (2000, p.85). Instead, he proposes a model that primarily focuses on multiple factors including psychological, social and management factors. Additionally, in this model, variables of human factors such as industrial equipment design, the physical environment and the task itself can cause accidents in isolation or in combination. Operator errors arise indirectly due to many reasons, such as low-level attentiveness, inadequate training, improper decision-making, social pressures and personality disorders.

Operator errors are classified into different categories depending on the task performance. The classification of these errors assists in the efforts of improving operator performance and prevents future recurrence. According to Ragman, operator errors belong to four categories: lapses, where an important action is omitted mistakenly, slips, which involves performance of a wrong action, knowledge-based errors and rule-based errors (1999, p. 12). Slips arise during the execution of a task due to low attention or wrongful perceptions. Pereira Lima categorizes the human errors depending on the industrial action (2000, p. 88). These include operator errors, manufacturing errors, design error and maintenance errors. Operator errors often occur during task performance. Rasmussen’s SRK theory identifies rule, skill and knowledge as the different levels of cognitive control that the operator normally uses during task performance (Wickens et al 1998, p. 81). The theory suggests that extensive experience will allow an operator to process raw and novel information subconsciously to achieve a high level of task performance (skill-based approach). In a situation where the operator is familiar with a particular task but lacks extensive experience, they often use a rule-based approach. Further, when the operators encounter a novel situation, their decisions will not be rule-based or skill-based but they use a knowledge-based approach, which involves analytical analysis of novel information.

Operator errors are of two types: errors of omission and commission (Wickens et al 1998, p. 86). Errors of omission arise due to an operator’s failure to perform a particular procedural step essential for the present situation he/she may be facing. In contrast, errors of commission arise when an operator errs in performing a particular step during task performance. Ragman, in addition to errors of omission and commission, identify the time error that arise when an operator is too slow or too fast in performing a task and the sequential error, where the operator fails to perform tasks in their right order (1999, p. 13).

The error rates in humans give an indication of the likely mistakes an operator will do in the course of task performance. In general contexts, the error rate in most humans is 0.5% during task performance. A study made by Tullo featured shocking revelations; pilots have an error rate of 10% when entering data into the flight management system and become higher in times of heavy workload (2001, p. 107). Thus, human error in aviation industry results from operator mistakes raising serious safety concerns. Norman suggests a criterion for determining the probability whether operator errors will arise in the course of task performance (1990, p. 5). Firstly, the management has to identify the goals and functions of the system, describe the tasks and the situation of use, review the tasks that have the likelihood of causing errors and identify the ways of increasing the reliability of the system.

Errors in Aviation and Aviation Psychology

Human errors in aviation can have severe consequences as it results to accidents that lead to of loss of life and huge economic costs to the airline company. As such, issues regarding air transport safety are important compared to ground or water transportation. Statistically, combination of human factors contributes to air crashes though natural factors can also contribute to crashes. Pilots have to undertake multiple tasks during flights including three-dimensional navigation, adhering to procedures of airline operations and communicating with the crew and the air traffic control. They are also supposed to maintain a situational awareness in case of any unforeseen situations in the airspace (Wickens et al. 1998, p. 111). All these tasks require intensive use of the pilot’s cognitive, perceptual and communication resources especially during distress situations.

In light of the high percentage of aviation accidents resulting from operator errors, the development of a safe aviation system focuses on the psychology of human operators. Human errors account for over 70% of accidents in the airline industry (Norman 1990, p. 6). The aviation psychology encompasses human aspects of cognition, perception and attention both at educational/training level and industrial level (Pereira Lima 2000, p. 89). This approach also involves aspects of aviation such as the design of the cockpit; the tasks performed by the pilot and the interaction between the pilot and the aircraft system in order to devise ways of improving pilot performance and reduce human error during a flight. In particular, the field aims at devising ways of prioritizing the information channeled to the pilot. Important flight information regarding the weather from the air traffic control, the rest of the crew and the flight engineers should reach the pilot in an organized manner (Busse 1999, p. 243).

Besides the human error-related aviation accidents, the design-related errors are also causes of aviation accidents. Errors during system design and maintenance can result to conditions that promote errors during flights. In addition, wrong trends in corporate decision-making by maintenance managers may indirectly contribute to flight errors (Reason 1990, p. 52). Different categories of error factors contribute to pilot error during flights (Busse 1999, p. 242). Of particular significance are the perceptual error factors such as misjudgment of distance or speed, visual illusion and lack of attention. Psychological or medical error factors including use of medication, fatigue or stress also contribute to human error during flights. In addition, skill-based or knowledge-based error factors are also a source of human error. These include inadequate knowledge on flight procedures or airline systems and poor performance of the flight procedures. Aviation psychologists identify excess motivation, overconfidence, frustrations/anger and social pressures as personality issues that can contribute to pilot error (Reason 1990, p. 56).

Other error factors include the operator decision or risk judgment factors. Failure to monitor the progress of the flight or ignoring warning signals often result to human errors during flights. In addition, undertaking a particular task without regard to safety or risks involved or willful neglect of the procedural rules and safety regulations can also result to human errors during a flight. Incorrectly prioritizing tasks without following the procedures or neglecting the prescribed flight parameters is another source of flight errors. Another category of error factors involves the crew communication factors. These may arise from inadequate crew preflight briefing or the failure to use an appropriate language in giving instructions. Misinterpretation of the safety instructions by the pilot or failure to crosscheck information received from the crew or airline control increases the potential of committing a mistake when executing the procedures.

Besides the human error factors, system design factors also contribute to flight errors. Failure of certain aspects of the system such as switch or control, operating systems or warning systems may indirectly contribute to operator error during a flight. Additionally, a variety of supervisory factors may contribute to human error. Operator errors can arise due to inappropriate task assignment to the crew by the management or failure to implement the minimum rest/duty hours recommended for pilots. Ineffective crew training practices coupled by the failure to establish efficient quality standards monitoring system can also cause human errors during flights.

Situational Awareness in Aviation Safety

Situational awareness encompasses successful operation of airline systems especially during distress situations. According to Bass, Zenyuh, Small and Fortin, a proficient operator must possess various forms of skills or knowledge (1996, p. 89). The operator must possess the operational skill to operate the complex airline system in a timely manner. He/she must also have procedural knowledge i.e. the capacity to perform a task procedurally. A declarative skill that involves the ability to make an appropriate decision on what to do is another skill essential to an operator. As a result, training on situational awareness should primarily emphasize on procedural skill and declarative skill development. However, the operational skills are also important especially in situations where the operator is required to make a decision over what action to take at a particular instance. Thus, maintain a situational awareness by operators is essential especially during risky and dynamic flight situations.

Maintaining a situational awareness entails the “conscious perception of various elements in the environment and the prediction of their status in the near future” (Bass et al. 1996, p. 92). The flight environment is often very dynamic and thus certain elements pertinent to safety may not be clear. As a result, the pilot must rely on current aspects of the flight environment to predict the future (Wickens et al. 1998, p.96). In other words, the pilot must attain a certain level of awareness relative to the current situation. In fact, most aviation accidents are attributed to the lack of situational awareness on the side of the operator. The impact of situation awareness especially on operators working involved in complex systems is profound. Thus, training the operators on how to achieve and maintain situational awareness is an important approach in promoting aviation safety.

Situation awareness is related to an operator’s performance and decision-making patterns. It reflects the operator’s ability to link the various elements of a dynamic flight environment with his/her own target goals. However, situation awareness is sometimes difficult to achieve especially for operators of complex systems. It entails the ability to acquire and process large amount of information necessary to operate efficiently in complex situations. Nevertheless, operators may fail to acquire the situational awareness because of time limitation, human-related limitations or system failure to provide data at an appropriate time (Bass et al. 1996, p.94). Problems related to system data arise from the failure to display the relevant data at an appropriate time making it difficult to detect potentially risk situations beforehand.

Human error when operating complex systems is largely responsible for industrial accidents. Consequently, the measures for preventing flight accidents primarily target at eliminating the situations that contribute to human error. One way of reducing human error involves the identification of the specific aspects of the system that contribute to the accident (Bass et al. 1996, p. 95). Instead of entirely blaming the operator, identification of the system inefficiencies would result to possible modification of the system to eliminate these incidents in the future. To reduce human error, one of the first things needed is a change in attitude. Thus, a major step towards eliminating operator errors and their consequences is by focusing on the system inefficiencies that contribute to human error.

Another way of reducing human error is through the development of system designs that facilitate human-system interaction. Design specifications should take into account the human operator in a way that promotes a high degree of task performance (Norman 1990, p.7). According to Wickens et al., operator error and their negative consequences can be minimized in three major ways: training of operation personnel, proper personnel selection and efficient system designs (1998, p. 105). With regard to system designs, people need to make efforts to develop systems that make it difficult or impossible for the operator to commit an error or incorporating a corrective mechanism into the system. Therefore, when operators make errors, their adverse effects are prevented. The corrective mechanisms should be able to give an operator a feedback about the immediate effects of a particular step or future consequences of particular actions. In addition, the system should be able to monitor the current operator actions for any errors. The design should also include features that allow errors in operator actions to be reversed when detected to avoid any effects on system performance.

Besides the system’s design approach to reducing operator error, operator training can significantly reduce the operator error. Since it is almost impossible to eliminate human error, personnel training and selection is essential in managing human error. In addition, proper personnel training helps in developing performance standards that emphasize on best practices to mitigate the consequences of human error. In managing human error, it is essential to identify errors that relate to human limitations (Ragman 1999, p. 11) as opposed to errors of omission or commission of procedural steps in task performance. In this way, operator errors can be recognized and accordingly resolved. Error management recognizes human performance as prone to error. Therefore, should be managed through appropriate training.

Thus, error management recognizes the fact that human error and human performance bear a connection. In addition, error management in personnel operation is built on the premise that human error a lone often does not result to accidents rather a combination of factors lead to industrial accidents or injuries (Reason 1990, p. 55). As such, only the consequences of operator error cause accidents or injuries not human error. From this perspective, though human error may be inevitable in personnel operations, its consequences such as accidents or injuries can be avoided. Thus, the error management strategies focus on reducing or eliminating the consequences of operator errors and consequently achieve aviation safety. Additionally, the recognition of the consequences of operator error shifts the blame from crewmembers to the actual causes of accidents or injuries.

Since operator errors do not cause accidents, focusing on the consequences of error is an important step towards managing operator errors. Human error management also focuses on technical efficiency of the operators. In other words, even efficient crewmembers or competent operators do perform errors during task performance. Therefore, operator personnel training should cover various aspects of task performance. Busse proposes that the training encompasses mental as well as psychological factors that significantly contribute to error reduction to promote aviation safety (1999, p. 244). Another way of ensuring better pilot training involves the use of procedural guidelines that guide operators on the procedure of task performance. Additionally, motivation in pilots can be achieved through the establishment of incentive programs that reward operators who detect errors and prevent consequences of human errors from causing accidents or injuries.


Operator errors and their consequences during making decisions or task performance often cause accidents or injuries. Efforts to promote aviation safety focus on reducing human error and improving situational awareness through training and proper system design. Operator errors fall into four categories: errors of omission and commission, sequential error and time errors. In reality, it is impossible to eliminate operator errors in aviation industry. Thus, instead of blaming the operator over an error, focus should target at identifying the consequences of errors that cause accidents or fatalities. In addition, addressing the human error factors through aviation psychology can serve to identify the factors that contribute to operator error.

In particular, the failure to maintain situational awareness either due to human factors or data retrieval problems, significantly contribute to operator errors. Thus, error management through appropriate operator personnel selection, training and efficient system design can reduce the operator error and their consequences.

Reference List

Bass, J., Zenyuh, P., Small, L., & Fortin, T., 1996. A Context-based Approach to Training Situation Awareness. Los Alamitos, CA: IEEE Computer Society. pp. 89-95.

Busse, D., 1999. On Human Error and Accident Causation. Interact, 7(2), pp.241-245.

Norman, A., 1990. Commentary: Human error and the design of computer systems. Communications of the ACM, 33, pp. 4-7.

Pereira Lima, E., 2000. Paradigm shift in the cockpit. Air Transport World, 37(11), pp. 85-89.

Ragman, T., 1999. Error management. Flying Safety, 55(8), pp.12-15.

Reason, J., 1990. Human Error. London: Cambridge University Press. pp. 52-57.

Tullo, J., 2001. Responses To Mistakes Reveal More Than Perfect Rides. Aviation Week & Space Technology, 154(21), pp.106-112.

Wickens, D., Gordon, E., & Liu, Y., 1998. An Introduction to Human Factors Engineering. New York: Addison-Wesley Educational Publishers Inc. pp. 76-107.

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