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You Don’t Understand Murphy’s Law: The Importance of Defensive Design

CALLBACK is the monthly newsletter of NASA’s Aviation Safety Reporting System (ASRS)1. Each edition features excerpts from real, first-person safety reports submitted to the system. Most of the reports come from pilots, many by air traffic controllers, and also the occasional maintainer, ground crew, or flight attendant. Human factors concerns feature heavily and the newsletters provide insight into current safety concerns2. ASRS gets five to nine thousand reports each month, so there’s plenty of content for the CALLBACK team to mine.

The February 2022 issue contained this report about swapped buttons:

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Agile SE Part Four: Digital Transformation

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A quick detour

This article is a quick detour on an important enabler for agile systems engineering. “Digital transformation” means re-imagining the way businesses operate in the digital age, including how we engineer systems. As future articles discuss scaling agile practices to larger and more complex systems, it will be very helpful to understand the possibilities that digital engineering unlocks.

Digital engineering enables the agile revolution

The knee-jerk reaction to agile systems engineering is this: “sure, agile is great for the speed and flexibility of software development, but there’s just no way to apply it to hardware systems”. Objections range from development times to lead times to the cost of producing physical prototypes.

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Agile SE Part Three: Agile Contracts and the Downfall of Requirements

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The antithesis of agile

Requirements are a poor way to acquire a system. They’re great in theory, but frequently fail in practice. Writing good requirements is hard, much harder than you’d think if you’ve never had the opportunity. Ivy Hooks gives several examples of good and bad requirements in the paper “Writing Good Requirements“. Poor requirements can unnecessarily constrain the design, be interpreted incorrectly, and pose challenges for verification. Over-specification results in spending on capabilities that aren’t really needed while under-specification can result in a final product that doesn’t provide all of the required functions.

If writing one requirement is hard, try scaling it up to an entire complex system. Requirements-based acquisition rests on the assumption that the specification and statement of work are complete, consistent, and effective. That requires a great deal of up-front work with limited opportunity to correct issues found later. A 2015 GAO report found that “DoD often does not perform sufficient up-front requirements analysis”, leading to “cost, schedule, and performance problems”.

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Agile SE Part Two: What’s Your Problem?

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A faster horse

“If I had asked people what they wanted, they would have said faster horses.”

Apocryphally attributed to Henry Ford1

When people trot out that quote they’re often trying to make the point that seeking user feedback will only constrain the design because our small-minded <sneer>users</sneer> cannot possibly think outside the box. I disagree with that approach. User feedback is valuable information. It should not constrain the design, but it is essential to be able to understand and empathize with your users. They say “faster horse”? It’s your job to generalize and innovate on that desire to come up with a car. The problem with the “singular visionary” approach is that for every wildly successful visionary there are a dozen more with equally innovative ideas that didn’t find a market.

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Agile SE Part One: What is Agile, Anyway?

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What is “Agile”?

Agile is a relatively new approach to software development based on the Agile Manifesto and Agile Principles. These documents are an easy read and you should absolutely check them out. I will sum them up as stating that development should be driven by what is most valuable to the customer and that our projects should align around delivering value.

Yes, I’ve obnoxiously italicized the word value as if it were in the glossary of a middle school textbook. That’s because value is the essence of this entire discussion.

Little-a Agile

With a little-a, “agile” is the ability to adapt to a changing situation. This means collaboration to understand the stakeholder needs and the best way to satisfy those needs. It means changing the plan when the situation (or your understanding of the situation) changes. It means understanding what is valuable to the customer, focusing on delivering that value, and minimizing non-value added effort.

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The Operations Concept: Developing and Using an OpsCon

  • An Operations Concept is more detailed than a Concept of Operations
  • It is a systems engineering artifact that describes how system use cases are realized
  • It is versatile and serves many uses across the project
  • There is no set format, though there are some best practices to consider

Concept of Operations (ConOps)

Let start by talking about the OpsCon’s better-known big brother, the ConOps.

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Agile SE Part Zero: Overview

“Agile” is the latest buzzword in systems engineering. It has a fair share of both adherents and detractors, not to mention a long list of companies offering to sell tools, training, and coaching. What has been lacking is a thoughtful discussion about when agile provides value, when it doesn’t, and how to adapt agile practices to be effective in complex systems engineering projects.

I don’t claim this to be the end-all guide on agile systems engineering, but hope it will at least spark some discussion. Please comment on the articles with details from your own experiences. If you’re interested in contributing or collaborating, please contact me at benjamin@engineeringforhumans.com, I’d love to add your voice to the site.

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Learn from the mistakes of others

The problem with being too busy to read is that you learn by experience… i.e. the hard way. By reading, you learn through others’ experiences, generally a better way to do business…

General James Mattis

The most successful people in any profession learn from the experiences of others. You can learn from their successes, sure. But don’t focus on doing things exactly they way they did, you’ll stifle your own innovation. Instead, understand their successes, extract relevant lessons, and forge your own path.

More importantly, learn from others’ failures and mistakes.

That’s why I publish a Reading / Listening List. As of the publishing of this article, 5 of the 6 recommendations are about poor engineering and design1. I find these stories fascinating, enlightening, and valuable. By avoiding the pitfalls of the past, we improve the likelihood of success in our own projects.

It’s okay to make mistakes, but strive to at least make original mistakes.

Board man gets paid

For years I’ve been advocating for the effective inclusion of human systems integration (HSI) in the systems engineering (SE) process. I had to address a persistent misunderstanding of what HSI is and how it relates to human factors; while that can be frustrating, I recognized that it wasn’t going to change overnight. Instead, I worked diligently to share my message with anyone who would listen.

Recently, my diligence paid off. I was contacted by a group putting together a proposal for a defense contract. The government’s request outlined their expectations for HSI as part of the systems engineering effort in a way that the proposal team hadn’t seen before. Someone on the team had heard me speak before, knew I had the right expertise they needed, and reached out to request my support.

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