Safety Analysis System Safety

Foundations of Safety Assessment

In this post on the Foundations of Safety Assessment, I’m going to look at the (few) things that we need to do in every System Safety Program.

Because we don’t always need to do everything. We don’t always need to throw everything at the problem. Some systems are simpler than others, and they don’t need the ‘whole nine yards’ in order to get a decent result. With that knowledge, we’re going to be able to design an analysis program for different applications or for different systems.

As an example, I’m going to use Military Standard 882E (Mil-Std-882E). Under that standard we would use these Tasks:

  • Task 201 – Preliminary Hazard Identification;
  • Task 202 – Preliminary Hazard Analysis; and
  • Task 203 – System Requirements Hazard Analysis.

(You will also find related material in my posts on Safety Analysis Techniques Overview and tailoring your Risk Analysis Program.)

Foundations of Safety Assessment – The Big Picture

I promised you we were going to look at the overview of the sequence.

And I think this is what pulls it all together and explains it powerfully. So the background to this is we’ve got, an accident or mishap sequence. Whatever you want to call it and we start with causes on the left and causes lead two a hazard, and then a has it can lead to multiple consequences.

Bowtie diagram showing five types of hazard analysis.
Bowtie showing the Foundations of System Safety

That is what the bowtie here is representing. It’s showing that multiple causes can lead to a single hazard, and a single hazard can lead to multiple consequences.

Don’t worry too much about the bow tie. I’m not pushing that in particular, it’s a useful technique, but it’s not the only one. We’ll come onto that – that’s the background.

This is the accident sequence we’re trying to discover and understand. I’m going to talk a lot about discovery and understanding.

Preliminary Hazard Identification

Typically, we will start by trying to identify hazards. There are techniques out there that will help us identify hazards associated with the system being used in a specific application, or purpose, in a specific operating environment.

Always bear in mind those three questions about the context, that help us to do this. What’s the system? What are we using it for? and in what environment?

And if we change any of those things, then probably the hazards will change. But we start off with preliminary hazard identification, which is intended to identify hazards. There’s a big, big arrow pointing at hazards, but also, inevitably, it will identify causes and consequences as well, because it’s not always clear. What is the hazard when you start? talking of discovery, we’re going to discover some stuff.

We may finally classify what we’re talking about later. we’re trying to discover hazards. In reality, we’re going to discover lots of stuff, but mainly we hope hazards, that’s stage one.

System Requirements Hazard Analysis

Now, then we’re actually going to step outside of the accident sequence itself. We’re going to do some requirements analysis, and the requirements analysis has to come after the PHIA because some safety requirements are driven by the presence of certain hazards.

If you’ve got a noise hazard somebody’s hearing might be affected, then regulations in multiple countries are going to require you to do certain things to monitor the noise. Let’s say or monitor the effect that it’s having on workers and put in place a program to handle that. The presence of certain hazards will drive certain requirements for safety controls or risk controls.

Then there are the broader requirements. Analysis of what the law requires, what the regulations require, codes of practice, etc. We’ll get onto that, and one of the things that requirements analysis is going to do is give us an initial stab of what we’ve got to have – certain controls because we’re required to. That’s a little bit of an aside in terms of the sequence, but it’s very, very important.

Preliminary Hazard Analysis

Thirdly, and, fourthly, once we’ve discovered some hazards, we’re going to need to understand what might cause those hazards and therefore how likely is the hazard to exist in particular circumstances, and then also think about the consequences that might arise from a hazard. And once we’ve explored those, we will be in a position to actually capture the risk.

 Because we will have some view on likelihood. And we would also have some view on the severity of consequences from considering the consequences. We’ll come onto that later.

Looking at Controls

Finally, having done all those other things, we will be in a position to take a much more systematic look at controls and say, we’ve got these causes. We’ve got these hazards. We’ve got these potential consequences.  What do I need to do to control this risk and prevent this accident sequence from playing out?

What I need to put in place to interrupt the accident sequence, and I’ve put the controls. The dashed lines indicate that we’ve got barriers to that accident sequence, and they are dashed because no control is perfect. (Other than gravity. But of course, if you turn your vehicle upside down, then gravity is working against you, so even gravity isn’t foolproof.)

No control is 100% effective. We need to just accept that and deal with that, and understand. There is your overview of the sequence, and I’ve spent a bit of time talking about that because it is absolutely fundamental to everything you’re going to do.

Well, That’s a Brief Summary of the Foundations of Safety Assessment

You can see the whole thing in the course bundle here.

If you have any questions then leave a comment, below.

Course System Safety

The Safety Artisan is on Thinkific

I’m pleased to tell you that The Safety Artisan is on Thinkific!

Thinkific is a powerful and beautifully-presented online Learning Management System.  This will complement the existing Safety Artisan website.  

My first course will be ‘System Safety Assessment‘ with ten hours of instructional videos. The new course is here.

(Please note that this is the same course as my ‘Complete System Safety Analysis Bundle’ of 12 videos available here.  So, if you’ve already bought that – thanks very much – please don’t buy it again, as you already have all the material.)

What will the System Safety Assessment Course do for you?

Transcript of the Video

Read the Transcript Here:

Welcome to the System Safety Assessment course

In this course, you will gain knowledge, skills, and confidence.  You will gain knowledge of what is involved in system safety assessment.  The individual tasks and techniques you need to carry out.

But more importantly, how to put them together into a successful program and how to tailor all these different tasks keeping some, but leaving out others so that you get an efficient and effective safety program, no matter what application or what system you are working with.

So that’s the knowledge and the skills

You’ll also get the confidence to be able to get you started.  Now, there is no substitute for live face-to-face training and coaching.  But this format is much more accessible to you and much more reasonably priced.  So wherever you are in the world, whatever time and day you want to do your learning, you can access this course and you can gain confidence to get you started.

So if you’re worried about a job interview, what you’re going to say or you’re worried about how to do a job and there’s nobody around to help you.  Then this course will give you the confidence to get started and to be aware of the pitfalls before you begin.

So what makes me confident that I can help you?

Well, first of all, I’ve got 25 years of experience applying system safety.

And I’ve done that in the UK, in the United States, in Australia, and in the European Union.  I’ve seen a wide variety of legal jurisdictions that I’ve worked in.  Also, I’ve worked on a wide variety of systems.  I’ve worked on planes, trains, ships and submarines, software, and I.T. systems all kinds of stuff.

I’ve worked on some gigantic multibillion-dollar projects and some much smaller ones.  So I know how to pragmatically apply this stuff, at a reasonable scale without spending stupid amounts of money.

And in fact, as part of my job as a consultant, I spent half the time telling clients to do less and spend less and still get an effective result.  So that’s where I’m coming from.

I’ve also got experience teaching system safety in the classroom.  I’ve taught hundreds of students, from various different projects.  And now I have hundreds of online students, and I’m very pleased to be able to help all of those as well.

So that’s why I think that I can help you

And I hope that you will enjoy this course and get a lot out of it.  Thanks very much for considering The Safety Artisan.

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