Principle 10. Equivalence

Principle 10. Equivalence


Success and failure come from the same source – ordinary work

Focus not only on failure, but also how everyday performance varies, and how the system anticipates, recognises and responds to developments and events

"When wanted or unwanted events occur in complex systems, people are often doing the same sorts of things that they usually do – ordinary work." Image: © Naviair (All rights reserved)

When things go wrong in organisations, our assumption tends to be that something or someone malfunctioned or failed. When things go right, as they do most of the time, we assume that the system functions as designed and people work as imagined. Success and failure are therefore thought to be fundamentally different. We think there is something special about unwanted occurrences. This assumption shapes our response. When things go wrong, we often seek to find and fix the ‘broken component’, or to add another constraint. When things go right, we pay no further attention.

Looking back, what makes performance look different is time for scrutiny, deconstruction and hindsight. Everyday work is not subject to examination because things are going well, and that is thought to be unremarkable. It is assumed that people are behaving as they are supposed to according to rules, procedures and standard working methods, i.e. work-as-imagined.

This bimodal view of performance (function vs. malfunction) underlies Safety-I, and may be well-suited to mechanical systems, but less so to complex socio-technical systems (see EUROCONTROL, 2013). In such systems, success and failure emerge from ordinary work – they are equivalent. When wanted or unwanted events occur in complex systems, people are often doing the same sorts of things that they usually do – ordinary work. What differs is the particular set of circumstances, interactions and patterns of variability in performance. Variability, however, is normal and necessary, and enables things to work most of the time.

Ordinary work occurs within the context of system conditions – demand and pressure, and resources and constraints. System conditions influence system behaviour, including patterns of interactions and flows, trade-offs, and performance variability. Success and failure therefore emerge from system behaviour, which is shaped or influenced by system conditions.

While we tend to focus our safety efforts and resources on things that go wrong (occurrences and risks), we need to shift more towards system behaviour and system conditions in the context of ordinary work. In practice, this means understanding how the work really works, how the system really functions, and the gaps between work-as-imagined and work-as-done. On this basis, it would be more effective to investigate the system, not just an occurrence. As Seddon (2005) put it, “How does the work work? How do current system conditions help or hinder the way the work works?”

System behaviour reveals itself over time. This means that understanding ordinary work is especially important, because performance can change quickly or drift into an unwanted state over time. Performance variability may propagate from one activity or function to others, interacting in unexpected ways, with non-linear and emergent effects. This may occur with or without component failures.

Whether variability is short- or longer-term, stable, fluctuating or drifting, it can be difficult to anticipate and recognise unless attention is being paid to normal work. When relying on reactive safety data concerning malfunctions, developments may occur too quickly to notice or so slowly that no-one notices. The causation may be complex and hard to understand. It may be difficult or impossible to respond.

A proactive approach involves continuously monitoring the system and its capability. The aim is to improve system effectiveness by improving the system’s ability to anticipate, respond and learn. This may involve working on demand, providing better resources, adjusting interactions, improving flow, or increasing flexibility and responsiveness by removing unnecessary constraints. By improving the number of things that go right, safety improves, and other important objectives are met.

Practical advice

  • Understand everyday work. To understand success and failure, we need to understand ordinary work and how work is actually done. Consider end-to-end flows and interactions, trade-offs and performance variability in the context of the demands and pressures, and the resources and constraints. Use a safety occurrence as an opportunity to understand how the work works and how the system behaves.
  • Observe people in context. This can be done using a variety of observational approaches, formal and informal. It is not about checking compliance with work-as-imagined, but rather seeing and hearing how work is done (including how people adjust performance and make trade-offs), in a confidential and non-judging context.
  • Talk to field experts about ordinary work. Observation is important, but alone it is insufficient to understand work-as-done. Talking to people in discussion (e.g. talk-through sessions, focus groups) helps to understand the how and why of work-as-done.
  • Improve resilience with systems methods. Use systems methods to understand how the system anticipates, recognises and responds to developments and events.

View from the field

Fernando Marián de Diego Air Traffic Controller, Spain; Head of the Technical Office: Spanish ATCO Professional Association (APROCTA)

“We ATCOs and pilots work with procedures and technology that are designed to be invariable. But with variable demands, people are the only part of the system that provide the needed flexibility to absorb and handle this variety. We need to predict, recognise and respond to the constantly changing situation at the right time and in the right way. Whenever a difficult or unusual situation arises, a natural instinct for helpful cooperation shows up with great intensity on both sides of the radio. Every request, advice, or instruction affects the outcome of the event. Success or failure come from same thing – everyday work and our ability to ‘see’, adjust and adapt. And looking at the safety of aviation operation, it works!”

Source: Systems Thinking for Safety: Ten Principles. A White Paper. Moving towards Safety-II, EUROCONTROL, 2014.

The following Systems Thinking Learning Cards: Moving towards Safety-II can be used in workshops, to discuss the principles and interactions between them for specific systems, situations or cases.

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