The Swiss Cheese Model Of Errors and Mistakes in UX

"If only I hadn't decided to take a shortcut, I wouldn’t have had the accident" OR"If only I had checked before hitting send, it would have saved me"

These thoughts only come in hindsight, when the mistake seems obvious. But failures rarely happen because of one big error. They happen when multiple small issues align at the worst possible time.

James Reason’s Swiss Cheese Model explains this perfectly.

Think of every system, whether it's an airplane cockpit, a hospital workflow, or a digital product, as a stack of Swiss cheese slices. Each slice represents a layer of defense: safety checks, design elements, or system safeguards.

But here's the catch, each slice has holes. Gaps where errors can slip through. A disaster only happens when all the holes align, creating a direct path for failure.

This happens in UX all the time:

• A confusing interface makes you click the wrong button.

• Lack of a confirmation prompt turns into an irreversible mistake.

• No undo option means one misstep is a permanent loss.

It’s easy to blame "user error," but in reality, it's a failure of design defenses.

How Do We Prevent These Failures?

1. Add more slices of safety – Build redundancies, checkpoints, and fail-safes.

2. Shrink the holes – Reduce the likelihood of errors through better design.

3. Detect early – Use alerts, monitoring, and validation to catch issues before they escalate.

The best designs don’t expect users to be perfect. They anticipate mistakes and build layers of protection around them.

Because in any complex system, aviation, healthcare, finance, or digital products, failures don’t happen in isolation. They happen when every hole in the Swiss cheese stack aligns.

The key is to design experiences that ensure those layers never align.