A Practical Breakdown for the Average Person

Introduction: The Mystery of Systems Engineering

If you ask ten different people what a systems engineer does, you’ll probably get ten different answers—some more confused than others. It’s one of those professions that sounds important (and it is), but most people, even in the engineering world, struggle to define it concisely.

At its core, systems engineering is about making complex things work together. Whether it’s a spaceship, an electric car, or even a supply chain, systems engineers ensure that all the moving parts function as a cohesive whole. They manage trade-offs, coordinate between disciplines, and ensure that what gets built actually solves the problem it was intended to solve.

Let’s break this down into a practical, real-world explanation—no jargon, no ambiguity, just straight talk about what systems engineering really means.

From Capability Needs to Requirements: The Foundation of Systems Engineering

Every system starts with a need. A company, government agency, or individual identifies a problem and says, “We need a system that can do X.” This is known as the capability need.

For example, NASA might say, “We need a way to get humans to Mars.” That’s a broad, high-level goal. From there, systems engineers break it down into use cases (what exactly needs to happen) and, most importantly, requirements.

Why Are Requirements So Important?

Defining and managing requirements is the backbone of good systems engineering. Here’s why:

• Keeps development on track – A clear set of requirements ensures the system does what it was designed to do, rather than morphing into something else halfway through development.
• Prevents scope creep – Every engineer has seen a project spiral out of control because people kept adding features. Good systems engineering stops this from happening.
• Ensures traceability – Every design decision should be linked to a specific requirement. If a feature doesn’t trace back to a requirement, it probably doesn’t belong in the system.

This is where Model-Based Systems Engineering (MBSE) comes in. Instead of tracking requirements in spreadsheets or Word documents (which get outdated fast), MBSE creates digital models that visually map out system requirements and their relationships. This makes it easier to see how everything fits together and ensures that the final product matches expectations.

Functional Decomposition: Defining What the System Must Do

Before designing hardware or writing a single line of code, systems engineers must figure out what the system actually does. This is called functional decomposition—breaking a complex system into its core functions.

Take a coffee maker. At a high level, its functions might include:

1. Heat water
2. Grind coffee beans
3. Brew coffee
4. Dispense liquid into a cup

For something more complex, like an autonomous vehicle, the functional breakdown might include:

1. Perceive the environment
2. Make driving decisions
3. Control movement
4. Monitor internal systems

Notice that we’re not talking about specific technologies yet—just functions. This ensures that we focus on what needs to happen before getting bogged down in how to make it happen.

The Systems “Vee” Model: Turning Concept into Reality

The Systems Engineering “Vee” Model is a structured way of developing a system from concept to deployment. It follows three main phases:

1. Left Side of the V (Concept & Decomposition)

• Define system needs and requirements
• Break the system into subsystems and components
• Develop initial designs

2. Bottom of the V (Detailed Design & Implementation)

• Design and build individual components based on functional needs

3. Right Side of the V (Testing & Validation)

• Verify each component works correctly
• Integrate subsystems and test them together
• Validate that the full system meets the original requirements

Think of it like building a house. You start with a blueprint (requirements and architecture), then build the foundation and structure (implementation), and finally inspect every room before moving in (testing and validation).

Risk Management: Avoiding Catastrophic Failures

A huge part of systems engineering is identifying and mitigating risks before they become expensive (or deadly) problems. Engineers use techniques like Fault Tree Analysis (FTA) and Failure Modes and Effects Analysis (FMEA) to systematically find weak points in a design.

Real-World Examples of Systems Engineering Failures

• NASA’s Mars Climate Orbiter (1999) – Engineers mixed metric and imperial units, causing the spacecraft to burn up in the Martian atmosphere.
• Therac-25 Radiation Machine (1980s) – A software glitch caused massive radiation overdoses, leading to fatalities.
• Tacoma Narrows Bridge Collapse (1940) – Engineers underestimated wind-induced oscillations, leading to dramatic structural failure.

Each of these failures highlights why proper risk management and verification processes are critical.

Agile Systems Engineering & MBSE: The Future of Development

Traditional systems engineering follows a rigid, sequential process. But modern technology development moves fast, requiring Agile Systems Engineering, where teams iterate quickly based on evolving requirements.

How MBSE Helps:

• Uses digital models to test and refine designs before building physical prototypes.
• Ensures requirements traceability, so engineers know exactly why every feature exists.

A great example is SpaceX, which rapidly iterates rocket designs, testing frequently and adapting based on real-world performance.

The Mindset of a Great Systems Engineer

According to Lee Gentry (JPL), the best systems engineers share these qualities:

• Intellectual curiosity – Always asking “why?”
• Big-picture thinking – Seeing how everything connects.
• Managing dependencies – Knowing how one change affects the entire system.
• Comfort with uncertainty – Adapting to changing requirements.
• Proper paranoia – Anticipating failure before it happens.

Systems Engineers: The Glue Between Disciplines

Systems engineers don’t work in a vacuum—they connect multiple disciplines, including:

• Mechanical Engineering – Physical components, structures, and materials.
• Electrical Engineering – Power systems, circuits, and sensors.
• Software Engineering – Control algorithms, automation, and data processing.
• Thermal Engineering – Heat dissipation and environmental resilience.

An electric vehicle, for example, requires balancing battery life, weight, performance, and software controls—all of which require cross-disciplinary coordination.

Lifecycle Considerations: Designing for the Long Haul

Great systems engineers don’t just think about how to build something—they think about its entire lifecycle:

• How will it be maintained and upgraded?
• What happens at end-of-life?
• How do you ensure it remains reliable over decades?

For example, the International Space Station was designed with modular upgrades in mind, while many satellites are built for one-time use.

Conclusion: Why Systems Engineering Matters

Every complex product you use—your phone, your car, the airplane you fly in—was made possible by systems engineering. Without it, even the most brilliant technologies can fail catastrophically.

So next time you hear the term “systems engineering,” remember: it’s not about any one part of a system—it’s about making sure the whole thing actually works.