Copyright © Erik Hollnagel 2022
All Rights Reserved.
Erik Hollnagel
Professor, Ph.D.
Professor Emeritus
LiU (S), ENSMP (F), SDU (DK)
The chief motive of all human actions is the desire to avoid anxiety.
Ibn Hazm (994-1064)
Introduction
A system is said to perform in a manner that is resilient when it can sustain required operations under both expected and unexpected conditions by adjusting its functioning prior to, during, or following events (changes, disturbances, and opportunities). Whereas current safety management (Safety-I) focuses on reducing the number of adverse outcomes by preventing adverse events, Resilience Engineering (RE) looks for ways to enhance the ability of systems to succeed under varying conditions (Safety-II). It is therefore necessary to understand what this ability really means, since it clearly is not satisfactory just to call it ‘resilience’.
The Four Basic Potentials for Resilient Performance
The definition of resilient performance can be made more concrete by considering what makes resilient performance possible. Since resilient performance is possible for most, if not all, systems, the explanation must refer to something that is independent of any specific domain. Resilience engineering has proposed the following four basic potentials:
The Interdependence of the Potentials
The four potentials are clearly not independent of each other. For example, the potential to respond can benefit from, and perhaps even requires, the potential to monitor. Similarly, the potential to learn is likewise needed to improve the potentials to monitor and to respond. The four potentials can be seen as functions, and understanding how these functions are coupled is obviously essential for managing them. This will in each specific case require a description of the interdependence of the potentials that considers the nature of the activities and the operating conditions. Since the potentials can be seen as functions, it is possible to use the FRAM to do that.
A very simple FRAM model of the four potentials as generic functions is shown below. It shows that the four potentials depend on each other, which means that it is necessary to take these dependencies into account when trying to improve a specific potential. The model below is too simple to be of practical value, but a more detailed model - even on a generic level - can easily be developed.
Assessing the Systemic Potentials
More details about the systemic potentials and how they can be used in practice can be found in this recent report.
The forerunner to the SPM, the RAG, has been used in practice in a number of cases in, e.g., railways, off-shore, health care, and radiation protection. While there is no comprehensive list of practical examples, a Google Scholar search shows at least some of them. While interested readers are encouraged to do a search themselves (and share the results with me if possible), some examples are provided here:
Aaen-Stockdale, C. (2014). Oil and gas, technology and humans: assessing the human factors of technological change. Ergonomics, 57(6), 956-957.
Apneseth, K. (2010). Resilience in integrated planning. M.Sc. Thesis, Norwegian University of Science and Technology.
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has included the RAG as part of their holistic safety guidelines.
Ljunberg, D. & Lundh, V. (2013). Resilience Engineering within ATM - Development, adaption, and application of the Resilience Analysis Grid (RAG). University of Linköping, LiU-ITN-TEK-G--013/080--SE.
Steen, R., Ingvaldsen, G., & Patriarca, R. (2021). Engineering resilience in a prison's performance management system. Safety science, 142, 105367.
Júnior, M. M. C. PARADIGM SHIFT IN SAFETY MANAGEMENT IN THE BRAZILIAN ARMY AVIATION: PROPOSAL AND VALIDATION OF A RAG QUESTIONNAIRE.
(Last update 2022-02-15. To be continued ...)