3 times bad design endangered human lives

In 1992, Air Inter Flight 148 tragically crashed into the Vosges Mountains near Strasbourg, France, killing 87 people. At the heart of this disaster was a poorly designed autopilot interface. The plane's altimeter, a crucial instrument for safe navigation, was incredibly confusing. Instead of displaying altitude clearly, it used an unfamiliar scale that was easy to misinterpret. In this case, the crew mistakenly set the plane to descend too rapidly, leading to a fatal crash.

The design flaw here wasn’t just a small glitch—it was a fundamental misunderstanding of how pilots interact with their instruments. When critical controls aren't intuitive or clear, even experienced professionals can make catastrophic errors. This case serves as a reminder that interface design should always align with users' expectations and needs, especially in high-stakes environments.

The 1979 nuclear accident at Three Mile Island in Pennsylvania is one of the most infamous examples of how bad design can lead to disaster. Inside the control room, a chaotic array of buttons, switches, and alarms made it nearly impossible for operators to understand what was happening during the partial meltdown of the reactor. A key indicator light suggested that a critical valve was closed when it was actually open, leading to a series of mistakes that escalated the crisis.

This incident highlights the dangers of poor interface design in complex systems. When operators can't quickly and accurately interpret the information they're given, the consequences can be dire. The lesson here is clear: design should simplify, not complicate, especially when lives are at stake.

In the 1980s, the Therac-25 radiation therapy machine was involved in a series of accidents that caused severe injuries and deaths. The problem? A deeply flawed user interface. Error messages were vague and non-informative, leaving operators in the dark about what had gone wrong. Worse yet, safety mechanisms that should have prevented dangerous radiation doses were either poorly designed or completely absent. As a result, patients received massive overdoses of radiation, with devastating effects.

The Therac-25 disaster shows how critical it is to design with empathy and safety in mind, especially in the medical field. Users—whether they're doctors, nurses, or patients—need clear, reliable systems that safeguard against errors, not interfaces that make things worse.

These examples may seem distant from the digital world, but the core lesson applies across all design disciplines: design can shape experiences, foster trust, and, in extreme cases, impact lives. This is where Human-Centred Design (HCD) comes in. HCD is all about putting the user at the forefront, ensuring that designs are intuitive, safe, and effective by understanding users' needs, expectations, and behaviours.

In the digital world, poor design can still have serious consequences—though perhaps less dramatic than a plane crash or a nuclear meltdown, they can still deeply impact users. For example, think of a poorly designed healthcare website. If patients can’t easily find critical information or book appointments, their health could suffer. With an increasing amount of vital products, services and information being access online, the potential for real harm and disadvantage is as much a reality on the web as it is in the physical world.

Even something as simple as a confusing button label or a disorganised menu can create friction for users. If the design of a website or app isn’t clear, users may struggle to complete tasks, leading to frustration and lost trust. Just like in high-risk scenarios, clarity, simplicity, and alignment with user expectations is key.

Take, for instance, a travel booking site. If users can’t easily navigate through flight options, select their preferences, or understand the total cost breakdown, they’re likely to give up or make mistakes. Or imagine a banking app where critical information like account balances or transaction histories is buried under layers of menus—this could lead to users making financial decisions without full awareness, potentially resulting in overdrafts or missed payments.

By empathising with users, gathering feedback, and iterating on designs, we can build digital products that not only meet needs but exceed expectations. Whether designing a website, app, or complex system, the principles remain the same: prioritise the user, eliminate confusion, and strive for clarity.

Every design decision matters. The history of Air Inter Flight 148, Three Mile Island, and the Therac-25 machine teaches us that when design fails, the consequences can be severe. In the digital age, we have the power—and the responsibility—to design interfaces that are clear, intuitive, and human-centred, ensuring that our creations serve and support the people who use them.

If you need help taking a human-centred approach to your initiatives, we can help. Reach out and start the conversation today.