The Swiss Cheese Effect in Industrial Safety

We’ve all heard the phrase “close call.” In reliability and safety, though, a near miss is more than that. It’s your system waving a red flag — and whether you catch it or ignore it can make all the difference.

When Luck Isn’t a Strategy

Probably you've heard something like this - someone found a pressure relief valve jammed shut. Luckily, it was spotted during a routine check. Fixed. Logged. Moved on.

“Good catch,” someone said.

They were right — it was a good catch. But here’s the problem: luck isn’t a control measure.

That near miss wasn’t random. It was evidence of holes in our defenses that, on a different day, could have lined up and caused a serious incident.

The Swiss Cheese Model: A Clear Picture of Risk

The Swiss Cheese Model gives us a simple but powerful way to visualise system defenses.

Think of your organisation’s barriers as slices of Swiss Cheese:

• Procedures
• Training
• Inspections
• Equipment design
• Emergency response

Each slice is a layer of defense. Each hole is a weakness — a gap, a condition, or a failure waiting to align.

• A near miss happens when a hazard slips through some layers but is stopped by another barrier before it reaches the end.
• An incident happens when the holes in multiple layers line up perfectly, and the hazard passes through every defense.

Near misses show you where the holes already are, without the cost of an actual incident.

Where Sologic RCA Fits In

The Swiss Cheese Model helps you see the problem.

Sologic RCA helps you solve it.

Near misses highlight vulnerabilities — but to actually close those holes, you need a structured, evidence-based approach. That’s where Sologic’s 5-Step RCA methodology comes in:

1. Gather and Manage Data/Evidence

Capture the facts behind the near miss before they disappear.

2. Gather and Manage Data/Evidence

Define exactly what happened and what was nearly lost. Clarity here is critical.

3. Gather and Manage Data/Evidence

Build a Cause & Effect Chart that reveals how and why each barrier failed, and where the holes lined up.

4. Gather and Manage Data/Evidence

Identify actions that address system weaknesses, not just surface symptoms.

5. Gather and Manage Data/Evidence

Document, share, and track corrective actions to make sure the holes are truly closed.

By combining the Swiss Cheese Model with Sologic RCA, you move from just spotting weak layers to strengthening them permanently.

Why This Matters

Too often, near misses are brushed aside. “No one got hurt.” “Nothing broke.” “We fixed it already.”

Sound familiar?

The trouble is, if we don’t analyse near misses with the same rigour as incidents, we’re effectively relying on luck to keep us safe.

Near misses are low-cost opportunities to uncover systemic weaknesses before they cause real harm. And when you apply structured RCA, you don’t just fix one layer — you improve the whole system.

Final Thought

Every near miss is a free preview of a future incident. The Swiss Cheese Model shows you the holes. Sologic RCA gives you the tools to close them.

If your team’s near misses aren’t being investigated properly, you’re missing one of the most valuable learning opportunities you’ll ever get.

Apply Sologic RCA to near misses. Strengthen your layers. Prevent future incidents.