The “Requirements” category in systems engineering serves as a critical guide to defining, documenting, and maintaining system necessities. It begins with gathering inputs from stakeholders, which may include customer needs, legal obligations, or technical constraints.
In 1999, NASA lost the $125 million Mars Climate Orbiter because two teams wrote the same requirement in two different units — pound-force on one side, newtons on the other. Nobody fumbled the math. The math was fine. The requirement was ambiguous, and an ambiguous requirement is a landmine with a long fuse: it sits quietly…
Not all project uncertainties are created equal — so why do so many teams dump them into one undifferentiated pile? RAID and RAIDOC are register frameworks for tracking the things that can sink a project: Risks, Assumptions, Issues, and Dependencies — with RAIDOC adding Opportunities and Constraints. Used well, they turn vague anxiety into a…
Every requirement tells the system to do something. A safety requirement is different: it tells the system what must never happen, no matter what. A safety requirement is one whose failure could lead to harm — injury, death, or serious damage — which is exactly why it is written, verified, and traced to a higher…
There is a brutal rule of thumb in engineering: a requirements mistake caught at the desk costs a dollar to fix; the same mistake caught at testing costs a hundred; caught after the system ships, it can cost ten thousand or a life. Capturing and defining requirements is the work of getting those statements right…
A CONOPS tells you how a system will be used. But “the operator needs to respond quickly” is a vision, not something you can build or test. The real work sits in between. Defining operational requirements is the process of translating the operational concept (CONOPS) into specific, verifiable requirements an engineer can actually deliver against….
A misplaced word in a requirement can cost more than a missed deadline — it can cost a mission. That is why “define the requirements” is not a box to tick but a craft to master. Requirements definition is the work of turning raw stakeholder needs into a clear, complete, and verifiable set of requirements…
“The system should be user-friendly” is not a requirement — it is a wish wearing a requirement’s clothes. You cannot build it, test it, or prove you met it. SMART requirements fix that by demanding every requirement be Specific, Measurable, Achievable, Relevant, and Time-bound — five tests that turn a vague hope into something an…
At some point a project has to stop arguing about what the requirements are and agree: this is the set we are building. That agreed, frozen snapshot is the baseline. A requirements baseline is a formally reviewed and agreed set of requirements that becomes the reference point for design, development, and change control. Without a…
Here is a system that passed every test and still failed. It did exactly what the spec said — calculated the right numbers, returned the right answers — and was unusable, because it took eleven seconds to respond and fell over under ten users. Every functional requirement was met. The non-functional ones were never written…
Every requirement you write spawns a trail of evidence behind it — a model, a test result, a review record, a decision log. On a serious project those artifacts outnumber the requirements many times over. In systems engineering, an artifact is any work product created during development — a document, model, diagram, or record —…
