• Home
  • Engineering for Humans

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

Posted by Benjamin Schwartz on 21 February 2022

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:

Read More

Agile SE Part Four: Digital Transformation

Posted by Benjamin Schwartz on 3 January 2022

Table of Contents

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.

Read More

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

Posted by Benjamin Schwartz on 22 September 2021

Table of Contents

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”.

Read More

Agile SE Part Two: What’s Your Problem?

Posted by Benjamin Schwartz on 25 August 2021

Table of Contents

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.

Read More

Agile SE Part One: What is Agile, Anyway?

Posted by Benjamin Schwartz on 15 August 2021

Table of Contents

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.

Read More

The Operations Concept: Developing and Using an OpsCon

Posted by Benjamin Schwartz on 21 July 2021
  • 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.

Read More

“Diversity of thought” is the “all lives matter” of corporate inclusion efforts

Posted by Benjamin Schwartz on 9 June 2021

For at least the last decade, engineering companies have talked a great deal about “diversity and inclusion”. Inevitably, many people1 have the takeaway that this means “diversity of thought”. This is like telling a Black Lives Matter supporter that “all lives matter”; of course all lives matter, but that’s completely missing the point2. Diversity of thought is important to avoid groupthink and promote innovation; but that’s not the point of diversity and inclusion efforts3.

Diversity and inclusion means making sure that teams are actually diverse, across a range of visible and not-visible features. Why does that matter?

Read More

Agile SE Part Zero: Overview

Posted by Benjamin Schwartz on 3 June 2021

“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.

Read More

Human Factors Design Drives System Performance

Posted by Benjamin Schwartz on 28 March 2021

Bottom Line Up Front:

  • Human performance is a major factor in overall system performance
  • Humans are increasingly the bottleneck for system performance
  • Human factors engineering design drives human performance and thus system performance

Why care about humans?

In many system development efforts, the focus is on the capabilities of the technology: How fast can the jet fly? How accurately can the rifle fire?

We can talk about the horsepower of the engines and the boring of the rifle until the cows come home, but without a human pressing the throttle or pulling the trigger, neither technology is doing anything. A major mistake many systems engineering efforts experience is neglecting the impact of the human on the performance of the system.

Read More

Ergonomics

Posted by Benjamin Schwartz on 17 January 2021

The term ergonomics was coined by Wojciech Jastrzębowski in 1857 to mean “the science of work”1 with the goal of improving productivity and profit. He described the importance of physical, emotional, entertainment, and rational aspects of the labor and employee experience, but the context was squarely on factory-type production.

Over time, this has evolved into two, slightly different definitions.

Read More