The Swiss Cheese Model
How to stop small misses from becoming BIG failures
In this issue:
Part 1: Understanding the Swiss Cheese Model
What is the Swiss Cheese Model?
The Three Big Ideas
Part 2: Applying the Swiss Cheese Model in Leadership
The 4-Step Framework
Real-Life Scenarios Where This Model Could’ve Saved the Day
The Swiss Cheese Model Worksheet
Part 3: Going from here
Common Pitfalls and How to Avoid Them
Recommended Resources
Final Takeaway
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Let me take you back to early 2020. Yeah, it feels like a distant memory, doesn’t it?
The world was just starting to understand what COVID-19 was — and how quickly it could bring entire systems to a halt.
Here in Singapore, the government moved fast. But more importantly, it moved systematically.
Rather than rely on one perfect solution, they built layers of defense:
Border controls
Temperature checks, mandatory quarantine for inbound travelers
The TraceTogether app for digital contact tracing
Mask mandates
Public education campaigns
And eventually, vaccines
Each of these measures, on its own, wasn’t perfect. People still slipped through temperature checks. Some broke quarantine. Even vaccines weren’t 100% effective.
But together, these layers worked like a net. Each one had holes, but the holes didn’t always line up. And that meant the virus had fewer chances to slip through all the layers.
This is what the Swiss Cheese Model is all about.
Risk doesn’t vanish — it gets trapped in the layers. And when those layers are missing or misaligned, that's when trouble sneaks through.
What if we applied the same thinking in our teams and organizations?
I’ve seen too many teams fall apart not because of one big failure, but because of a series of small misses that lined up perfectly — just like the holes in slices of Swiss cheese. That’s what we’re going to unpack in this article.
Part 1: Understanding the Swiss Cheese Model
The Swiss Cheese Model was developed by British psychologist James Reason, and it started with a tragedy.
What is the Swiss Cheese Model?
In 1977, at Tenerife Airport in the Canary Islands, two Boeing 747s collided on the runway. 583 people died. It remains the deadliest accident in aviation history.
And yet — there was no mechanical failure. The disaster was caused by a chain of small human errors:
A bomb explosion at a nearby airport diverted dozens of flights to Tenerife, overcrowding it.
Thick fog blanketed the runway, making visibility nearly zero.
One pilot misheard the clearance to take off.
Air traffic control didn’t catch the error in time.
Any one of these, on their own, might not have caused a disaster. But stacked together, they became deadly.
James Reason studied incidents like these and proposed a new way to think about failure:
Every system has layers of defense.
Every layer has holes — weaknesses, oversights, flaws.
But when the holes line up, that’s when failure gets through.
This became known as the Swiss Cheese Model.
It’s now a standard in industries like aviation, nuclear energy, and healthcare — where stakes are high, and there’s no room for careless mistakes.
But it goes beyond that. As a leader, you may not be landing planes, but you’re still making high-stakes decisions with imperfect people under ambiguous conditions.
So, consider this an essential part of your leadership toolkit. Let’s now dive into how this model works.
The Three Big Ideas
The model has three big ideas.
1. Every system has layers of defense
In a company, this could be:
QA teams
Peer reviews
Checklists
Dashboards
Leadership reviews
Culture that encourages people to speak up
Each layer is meant to catch errors. The more layers, the better your chances.
2. Every layer has holes
These are the gaps:
A process step that’s often skipped
A reviewer who’s overloaded
A metric that’s tracked but not interpreted
A meeting where people stay silent
No layer is perfect. That’s okay. The goal is not perfection. The goal is redundancy.
3. When the holes line up, failure slips through
This is what happens in most real-world incidents. No single thing causes the issue.
The good news is that for the failure to cause real damage, multiple holes need to line up. If you break the chain at any point, you stop the failure.
That’s the beauty of the Swiss Cheese Model.
Part 2: Applying the Swiss Cheese Model in Leadership
In this section, you will learn how to apply the Swiss Cheese Model in your role as a leader.
We will start by reviewing The 4-Step Framework that you can use to start applying this framework right away.
We will then discuss some common real-life leadership scenarios, and how you would apply this framework in each of those.
Finally, we will make it real with the Swiss Cheese Model Worksheet, which will help you build your muscle in applying and using this framework in your leadership role.