Systems engineering is essential to software development in critical systems. Though it is essential, it is often overlooked for the need to “move fast and break things” that most Agile developers desire. There is a direct conflict that many see between the Agile Manifesto and the need to have a fully documented and well-engineered system. Critical software systems cannot afford the high rate of defect generation that pure Agile executions output. Therefore, systems engineering must be incorporated into the development cycle of these systems.