No theory forbids me to say "Ah!" or "Ugh!", but it forbids me the bogus theorization of my "Ah!" and "Ugh!" - the value judgments. - Theodor Julius Geiger (1960)

Vive la Diversité: HRO and RE


Jean-Christophe Le Coze discusses the evolution of the field of safety over the past 30-40 years, highlighting the impact of globalization, technological developments, and ecological awareness on safety practices. Le Coze then focuses on two research traditions, High Reliability Organisation (HRO) and Resilience Engineering (RE), which have become central to the field of safety but have raised questions about their similarities, differences, and the use of new vocabulary. Le Coze emphasizes the diversity within each tradition, with authors from various disciplines contributing to HRO and RE. The paper aims to explore the historical development of these traditions, acknowledging the limitations of space in delving into the depth of empirical, methodological, and conceptual aspects. Notable authors associated with HRO and RE are mentioned, with recognition of their diverse backgrounds and interests. The paper aims to characterize the commonalities binding authors within each research tradition, highlighting that RE is rooted in engineering, human factors, and cognitive engineering, while HRO is rooted in social sciences, including social psychology, organizational psychology, sociology, and political sciences. Despite their differences, exploring the complementarities of the two schools can contribute to the study of high-risk systems. Le Coze advocates for the celebration of diversity in styles, methods, concepts, and purposes in the safety field. The exploration of the relationship between HRO and RE is an opportunity to reflect on safety as a practical, scientific, and academic field, fostering a broader understanding of various approaches to safety research.



The High Reliability Organizations (HRO) school emerged in the 1980s, primarily through the efforts of Todd La Porte, Karlene Roberts, Gene Rochlin, Paul Schulman, and Karl Weick, who conducted ethnographic work to address the theoretical challenge of achieving nearly error-free operations in high-risk systems like nuclear power plants. The research explored how personnel in such systems could learn when mistakes were not permitted. Over a period of 10-15 years, the group produced a significant body of work, including communications, chapters, articles, and books, which collectively defined the contours of the HRO research tradition. These works were published in journals such as the Journal of Contingencies and Crisis Management, Organisation Science, Public Administration, Administrative Science Quarterly, and California Review of Management.


The research on HRO emphasized the need for new theoretical developments to understand the complexities of high-risk systems, such as aircraft carriers, nuclear power plants, and air traffic control. Traditional organizational theory was concluded to be inadequate for addressing the unique challenges posed by these systems. They introduced concepts like "collective mindfulness" to describe sociocognitive processes supporting safe operations in these high-risk environments.

The HRO tradition engaged in a central debate regarding Charles Perrow's thesis on normal accidents, which suggested that tight coupling and high complexity could lead to catastrophic failures. While the HRO researchers found Perrow's contribution valuable, they also debated the implications of his thesis.

Collective mindfulness became a key feature of the HRO tradition, appealing to practitioners and contributing to the success of HRO in various domains, including healthcare.

HRO is rooted in organizational theory and political sciences, and gained strength by ethnographically studying high-risk systems, debating principles for organizational reliability, and integrating these principles into collective mindfulness.


Resilience Engineering

Resilience Engineering (RE) was developed in connection with cognitive engineering, human factors and ergonomics, and system safety engineering. The key figures in the development of RE include Rasmussen, Reason, Woods, and Hollnagel, who contributed to the core program of integrating engineering, risk assessment, and the study of human error.


Jens Rasmussen did pioneering work in cognitive engineering, studying human error and cognition, particularly in relation to the design of human-machine interfaces. After the Three Mile Island incident in 1979, international researchers, including engineers, psychologists, and cognitive scientists, focused on understanding human error. Two orientations emerged in the study of errors: a taxonomic option, led by Reason, and a naturalistic option, emphasizing errors as part of an adaptive and exploratory side to cognition. The latter option viewed errors as compensable and intrinsic to learning.

The New View of safety, advocated by Woods, Cook, Rasmussen, and others, focused on expertise and the ability of individuals to cope with complexity, rather than solely on errors. The variability of performance was stressed. This approach was applied and theorized in various domains, such as aviation, healthcare, and nuclear fields. The New View was intended to provide practical solutions for human reliability assessment and interface design.


The second aspect of Resilience Engineering involves a system view of safety and accidents. James Reason introduced the concept of latent errors, suggesting that accidents are not produced by front-line individuals but by errors made earlier by decision-makers. The defense-in-depth model, often referred to as the Swiss Cheese model, graphically illustrates this idea. Jens Rasmussen extended his findings on cognition to organization, proposed the concept of migration and the principle of the defense-in-depth fallacy. This concept was later applied through notions like practical drift and resonance.

The Resilience Engineering movement rests on Rasmussen's view of adaptive entities producing self-organized patterns through trade-offs in a space of resources and constraints, formalized further with the language of complex adaptive systems. Complexity ideas are explored with practical purposes by Hollnagel and the Functional Resonance Analysis Method. The engineering orientation of Resilience Engineering is important, with Hollnagel's consistent cycle of producing concepts and developing tools over 30 years.


So, Resilience Engineering has grown from the efforts of a network of authors since the 1980s, conceptualizing human error, introducing it in design and assessment contexts, and providing practical solutions. It has refined the New View of safety, incorporating a system view of safety and accidents, and embraced complexity ideas for practical applications. The engineering orientation of Resilience Engineering is evident in its focus on producing actionable models and methods.


Comparing HRO and RE

A comparison of High Reliability Organization (HRO) and Resilience Engineering (RE) shows common themes, exchanges, and differences between the two schools. The histories of HRO and RE run parallel for the past 30 years, with both producing articles, books, and chapters simultaneously. The two schools are independent. Notable examples of subjects include the discussion on situation awareness and the self-organizing features of high-risk systems, which are explored in both traditions from different perspectives. Differences between HRO and RE are conspicuous. 

Interdisciplinary Safety Science

High Reliability Organisation has its roots in social sciences, particularly with an ethnographic approach and empirical case studies. When HRO authors were studying topics such as aircraft carriers, air traffic control, and nuclear power plants in the 1980s, they were drawing from sociological perspectives to conceptualize the problem of error and its implications for interfaces design. Resilience Engineering, although not primarily leaning on sociological knowledge, engages with the social aspects of resilience, considering factors such as adaptation, self-organization, and complexity within the broader sociotechnical context.

Sociology focuses on topics such as socialization, culture, or institutional trust. Sociological perspectives, especially in HRO, offer valuable insights into areas like mindfulness, which has roots in social psychology and philosophy rather than the mainstream cognitive science relying on computer analogy. A sociologist's knowledge differs from that of a psychologist or cognitive scientist, and this diversity is important in safety research. Interdisciplinary strategies, incorporating disciplines like sociology, are needed to study the complex sociotechnological systems that contribute to safety. Trends in hybridization and interdisciplinarity suggest that insights from both RE and HRO are combined with other scientific domains, enhancing the understanding of safety in complex sociotechnological systems.



Le Coze, J.C. (2019), Vive la diversité! High Reliability Organisation (HRO) and Resilience Engineering (RE), in: Safety Science, Volume 117, August 2019, Pages 469-478.