Systems Engineering

Systems engineering is the discipline that got people to the Moon and keeps aircraft in the air. It is how you design something large enough that no one person holds all of it, with failures expensive enough that you must reason about them before building. Its tools are plain: written requirements traced to tests, interfaces with owners, failure analysis done on paper first, trade studies with explicit weights, and a lifecycle that includes the day the system is switched off. Staff engineers in software rediscover these tools, usually after the incident that called for them.

Ten parts, worked through one running example: a service that issues loan clearance letters (a customer finishes repaying a loan and needs a signed letter saying they owe nothing). It is small enough to follow and regulated enough that every tool matters. What the discipline is and the V-model; requirements, including the ones nobody wrote down; interfaces and their control; failure analysis with FMEA, fault trees and safety cases; trade studies; and capacity, growth and whole-life cost. Four further parts follow: verification and validation, systems thinking, the operational concept and transition, and risk management, all on the same running example.