Systems Thinking
Systems thinking is an approach to viewing systems holistically, rather than focusing on component failures and on direct causal relationships between those components. Through this approach, the components or parts of a system are viewed as integrated and interactive, rather than isolated and independent, shifting attention to the ever-changing influences and relationships among all the different parts. Systems thinking also considers how a system performs within a larger system. Examining systems through this view is necessary to make sense of the connections and interactions among their components or parts. Some of these interactions are predictable or at least knowable. Systems thinking is critical to recognize the extent to which the interactions within a system are unpredictable, unknowable, and of equal or even greater interest than the performance and reliability of its individual components.
1. Types of Systems
The aviation system is comprised of systems varying in size and complexity. These systems are classified as simple, complicated, and complex. While systems thinking is particularly useful in the synthesis of complex systems, it is nonetheless important to understand the differences and interactions of these distinct classes.
Simple systems
A simple system is mechanistic, comprised of a defined number of components or parts which interact to accomplish one or a small number of known goals or functions. The behaviors of the system are fully predictable and do not change over time. Therefore, when the system is degraded or fails, cause is easily identifiable. The relationship between cause and effect is linear and clear. As such, these systems are straightforward to maintain and repair to ensure that they consistently meet their pre-identified performance standards.
Examples of simple systems within aviation:
- Passenger emergency lighting system used to guide passengers out of an aircraft in an emergency;
- Hydraulic cargo or cabin doors used to load and unload crew, passengers, and cargo;
- Hangar doors' tracks and hinges system used to gain or prevent access to the hangar and the ramp.
Complicated systems
A complicated system is also mechanistic in that all the parts, components, and their interactions are knowable. However, the structure and interactions in a complicated system may be difficult to understand, and the system may have multiple functions. Experts with appropriate qualifications can understand and analyze these systems with a high degree of accuracy. An understanding of linkages and interactions of system components is developed linearly, where an understanding of one element leads to an understanding of the next element. The impact of one element on another can be reasonably predicted. The relationship between cause and effect is linear. However, a single cause may have multiple effects, and a single effect may be the result of several possible causes.
Examples of complicated systems within aviation:
- Aircraft jet engine used to provide thrust, generate electricity and create hydraulic pressure;
- A fuel truck used to move fuel around the airfield, pump fuel and dispense it.
Complex systems
A complex system is dynamic. The whole of the system is greater than the sum of its parts and components. Interactions between parts and components are diverse and nonlinear because everything is connected to, and depending on, something else. The behaviors of these systems may change in unpredictable ways. Analysis - such as causal analysis - of complex systems is not an effective method to improve system performance because the behavior of the system cannot be predicted from examining the behavior of its separate parts, and the system cannot be understood by only looking at one component or from one perspective.
Complex systems often behave unpredictably or randomly due to the diversity of interactions within the system, the unpredictable nature of system components (such as humans or weather), and/or changing influences within the system. For example, an individual may change behavior, adapting to internal influences, such as health or personal mood, as well as to external influences, such as environment or equipment. A complex system may exhibit unpredictable behavior even though its performance may be defined by strict policies and procedures. Unlike simple or complicated systems, complex systems have the unique ability to learn and adapt, which can be attributed to the human component of the system.
Examples of complex systems within aviation:
- Operation of an aircraft;
- Maintenance of an aircraft;
- Air traffic management;
- Any system involving humans.
2. Supporting complex system performance
Command and control tactics such as compliance with Standards and procedures, and meeting prescribed training requirements typically work well for addressing simple- or complicated-system performance with its predictable interactions and behaviors. However, these methods are often not enough when the interactions within a system are very context dependent and unpredictable. Therefore, management of a complex system for the benefit of system performance requires additional approaches than for a simple or complicated system.
Systems thinking provides the foundation for identifying complex systems and for recognizing the limits of methods which were developed for handling simple and complicated systems. Systems thinking enables the development of strategies which can move system performance away from total reliance on prescriptive standards, regulations and rules to include more performance-based approaches that foster learning, adaptability, and resilience. These can develop when we value expertise, facilitate the sharing of perspectives, encourage transparency of information, and create an environment where decision making is driven by an understanding of context and a thorough analysis of credible data.
Systems Thinking and Safety Management
Safety Management is the process of managing risk within a system to the extent that risk is predictable. The core concepts of safety management work well for simple and complicated systems, and for the predictable interactions in complex systems. These core concepts sometimes fall short of acknowledging the full range and role of Human Performance, or other unpredictable aspects of a complex system. Nevertheless, Safety Management does provide a foundation for improving system performance also in complex systems.
Some challenges inherent in Complex Systems
- The innumerable interactions and interconnections of system parts and components create unpredictability;
- Small causes may have large effects; cause-effect relationships are nonlinear;
- There is the misconception that all risk within a complex system can be managed, measured, and controlled;
- Despite the best intentions and efforts, negative events can still emerge in normal organizations from normal people behaving in normal ways;
- Any change is likely to have unintended consequences.
Key concepts of Complex Systems
- Because humans are inherently complex, any system which involves a human component is a complex system;
- Humans are a primary source of learning and adaptability within complex systems;
- Compliance with prescriptive requirements does not always meet the challenges inherent in complex system performance, and may even constrain the performance of the system;
- System performance can be improved by moving away from traditional analysis methods and toward Systems Thinking.
3. Topics related to Systems Thinking