Model-Based Systems Eng. & Requirements Definition • Dennis Hansen & Jorge Orellana • GOTO 2026

This interview was recorded for the GOTO Book Club. #GOTOcon #GOTObookclub http://gotopia.tech/bookclub Dennis Hansen - Air Force Veteran, Chief Systems Engineer & Author of “Model-Based Systems Engineering and Requirements Definition” Jorge Orellana - Model Based Systems Engineer at IERUS Technologies & CEO & Founder at SCATTERBRAINS Check out more here: https://gotopia.tech/episodes/445 RESOURCES Jorge https://www.linkedin.com/in/jorge-orellana-0b729129 DESCRIPTION Dennis Hansen brings over six decades of systems engineering experience to this GOTO Book Club conversation — from Air Force airborne navigation technician to Chief Systems Engineer at L3Harris on programs including the complete rebuild of the GOES-R ground system for NOAA and NASA. His book argues that the fundamental failure mode in complex system development is the same every time: requirements are defined too loosely, too late, or across multiple model layers simultaneously. He structures the approach using an onion model — a layering framework he was taught by a Motorola engineer in 1961 — where each layer (mission, capabilities, activities, technical requirements, specifications) must be completed before the next is begun. Skipping layers or trying to do two at once invariably produces excess or faulty requirements that surface as expensive failures during system testing, or worse, after deployment. The second half of the conversation focuses on why modeling tools are databases, not drawing programs — a distinction Dennis considers critical. Every element in the model carries its associated requirements and the reasoning behind design decisions, which means that when you return to work after a weekend, you don't lose hours reconstructing your thinking. More importantly, when change requests arrive — and they always do — a maintained model lets you trace the impact backwards through the system and understand exactly what has to be modified, rather than slapping on a fix that creates five new problems. Dennis's closing advice is the thread that runs through the entire book: collaborate at every stage, every discipline working together rather than in silos, and define things properly upfront. Everything else follows from that. TIMECODES 00:00 Intro 02:26 How the book is structured: Document Development Flow 04:32 The Onion Model: Layered System Definition 06:36 The OV-1 done right: Beyond the cartoon graphic 10:51 SysML 13:45 SysML log-in activity diagram 15:50 Why you model: To learn, not just to document 19:05 How to start: From mission to first view 22:09 Outro RECOMMENDED BOOKS Dennis Hansen • Model-Based Systems Engineering and Requirements Definition • https://amzn.to/4e6IiqJ Kossiakoff, Seymour, Flanigan & Biemer • Systems Engineering Principles and Practice • https://amzn.to/4a7Elj9 Dr. Bruce Powel Douglass • Agile Model-Based Systems Engineering Cookbook • https://amzn.to/4wYnj12 https://bsky.app/profile/gotocon.com https://twitter.com/GOTOcon https://www.linkedin.com/company/goto- https://www.instagram.com/goto_con https://www.facebook.com/GOTOConferences #SystemsEngineering #MBSE #ModelBased #UML #DataModel #SysML #Programming #TodayInTech #DennisHansen #JorgeOrellana #BookClub CHANNEL MEMBERSHIP BONUS Join this channel to get early access to videos & other perks: https://www.youtube.com/channel/UCs_tLP3AiwYKwdUHpltJPuA/join Looking for a unique learning experience? Attend the next GOTO conference near you! Get your ticket at https://gotopia.tech Sign up for updates and specials at https://gotopia.tech/newsletter SUBSCRIBE TO OUR CHANNEL - new videos posted almost daily. https://www.youtube.com/user/GotoConferences/?sub_confirmation=1