Near-Miss: How “Near” Does it Need to Be?
How “Near” Does a Near-Miss Need to Be?
What is a near-miss? The term originated with the aviation safety community. When planes accidentally came closer than a certain minimum distance but did not collide, the planes were near but missed … a near-miss. You might think of it as nearly an accident or a close-call.
But how near does a miss need to be to be called a near-miss?
USA Today published this answer to the question:
The horizontal separation standard ranges from 3 to 5 miles and drops to 1 mile under certain conditions near an airport with parallel runways.
The vertical separation is 1,000 feet for other instrument traffic and 500 feet for visual traffic.
So for pilots, the definition is clear. See some ground near-misses (and collisions) in the video below.
Also, the term near-miss is used outside the aviation industry. For example, the driving instructor below is reacting to an auto near-miss…
What about near-misses at a:
- oil platform
- nuclear power plant
- manufacturing facility
- pharmaceutical plant
That’s a great question!
Your Definition of a Near-Miss
First, let’s start with your definition of a near-miss. Leave it as a comment below in the comments section.
I’ve heard all kinds of descriptions of what is a near-miss, and I hope we collect a variety below.
To get things started, the National Safety Council defines a near-miss as:
“…unplanned event that did not result in injury, illness, or damage – but had the potential to do so. Only a fortunate break in the chain of events prevented an injury, fatality or damage; in other words, a miss that was nonetheless very near.”
Using Safeguard Analysis to Define a Near-Miss
First, what is “Safeguard Analysis?” It is the analysis of Hazards (sources of energy) and Targets (things to keep safe) and the Safeguards (sometimes call Barriers) that keep the Hazard from reaching the Target.
If all the Safeguards fail, you have an accident.
In the model above, all the Safeguards have failed and allowed the Energy to reach the Target.
The cause of a Safeguard failing is a Causal Factor. Each Causal Factor has one or more root causes.
Sometimes Safeguards are shown using the Swiss Cheese Model.
If some Safeguards fail, but one or more Safeguards are successful in preventing the Energy (Hazard) from reaching the Target (as shown below), you could call that incident a near-miss.
If you are going to use Safeguard Analysis to define your near-miss, you will have to decide how much Energy needs to be present and how many Safeguards either need to fail before calling something a near-miss.
Below is the Energy Wheel. The amount of Energy needed to call something a near-miss might depend on the type of Energy.
Does Your Definition Produce Consistent Guidance
Many companies call for the investigation of near-misses. But are their definitions consistent (produce a uniform screen size)? When they consider different sources of Energy and different numbers of failed or successful Safeguards, does their evaluation result inconsistent data? Are your investigators investigating a cut finger, but not investigating a person working on a high-voltage line and narrowly misses being electrocuted (zero harm – no investigation)?
Uniform screen size should provide you with some food for thought. Is your guidance for doing an investigation across different types of hazards consistent? Maybe you should be thinking about updating your guidance on when to perform an incident investigation or near-miss investigation?
Want more guidance for your investigation policy. See Book 2, Appendix A…
Learn More About Safeguard Analysis and Root Cause Analysis
Want to learn more about Safeguard Analysis and to find the root causes of near-misses? Attend a TapRooT® Root Cause Analysis Course. See: