What Do We Mean by a System?

In systems engineering, a system is a collection of interrelated components that work together to achieve a specific goal or set of objectives. A system can be physical, such as an airplane or a power plant, or it can be conceptual, such as a business process or a software application.

A system can be decomposed into smaller subsystems or components, each with its own set of functions. For example, an airplane can be decomposed into subsystems such as the fuselage, wings, engines, and avionics. Each of these subsystems has its own set of design requirements and constraints, but they must all work together seamlessly to achieve the overall goal of safe and efficient flight.

Thinking more broadly, we could also think of the whole aviation system as a type of system – a system made up of organisations and people. This is where human factors starts to come into things.

Should Humans be Seen as part of the System?

The question of whether humans should be considered as system components is a topic of ongoing debate in systems engineering. Some argue that humans are an integral part of many systems, and should be treated as components with specific functions and requirements. Others argue that humans introduce unpredictability and variability into systems, and should be treated as external factors that can impact system performance.

While it may be tempting to simplify system definitions by excluding human components, this approach may not accurately reflect the complexity and interdependence of many real-world systems.

For example, in the context of an air traffic control system, human controllers play a critical role in ensuring the safety and efficiency of air traffic. While automated systems can assist with certain tasks, such as detecting potential collisions, human controllers are responsible for making decisions in real-time, based on their expertise and knowledge of the system. Excluding human components from the definition of the air traffic control system would not accurately reflect the reality of how the system operates.

Similarly, in the context of a healthcare system, human clinicians and staff are essential components of the system. While automated systems can assist with certain tasks, such as record-keeping and medication management, human clinicians are responsible for making diagnoses, determining treatment plans, and providing care to patients. Excluding human components from the definition of the healthcare system would not accurately reflect the reality of how the system operates.

As I’m sure that you have guessed by now, in this course we treat humans as an integral part of any system definition.