Mil-Std-882E Safety Analysis

Preliminary Hazard Identification

Want to know how to perform Preliminary Hazard Identification?  This is the first step in safety assessment.  We look at three classic complementary techniques to identify hazards and their pros and cons.  This includes all the content from Task 201, and also practical insights from my 25 years of experience with Mil-Std-882. 

This is the seven-minute-long demo video.

Topics: Preliminary Hazard Identification

  • Task 201 Purpose & Task Description;
  • Historical Review;
  • Recording Results;
  • Contracting; and
  • Commentary:
    • Historical Data;
    • Hazard Checklists; and
    • Analysis Techniques.
Transcript: Preliminary Hazard Identification

Hello, everyone, and welcome to the Safety Artisan, where you will find instructional materials that are professional, pragmatic and impartial, because we don’t have anything to sell and we don’t have an axe to grind. Let’s look at what we’re doing today, which is Preliminary Hazard Identification. We are looking at one of the first actual analysis tasks in Mil-Std-882E, which is a systems safety engineering standard from the US government, and it’s typically used on military systems, but it does turn up elsewhere.

Preliminary Hazard ID is Task 201

I’m recording this on the 2nd of February 2020, however, the Mil-Std has been in existence since May 2012 and it is still current, it looks like it is sticking around for quite a while, this lesson isn’t likely to go out of date anytime soon.

Topics for this session

What we’re going to cover is, quoting from the task, first of all, we’re going to look at the purpose and the task description, where the task talks quite a lot about historical review (I think we’ve got three slides of that), recording results, putting stuff in contracts and then I’m adding some commentary of my own. I will be commenting all the way through, that’s the value add, that’s why I’m doing this, but then there’s some specific extra information that I think you will find helpful, should you need to implement Task 201. In this session, we’ve moved up one level from awareness and we are now looking at practice, at being equipped to actually perform safety jobs, to do safety tasks.

Preliminary Hazard Identification (T201)

The purpose of Task 201 is to compile a list of potential hazards early in development. two things to note here: it is only a list, it’s very preliminary. I’ll keep coming back to that, this is important. Remember, this is the very first thing we do that’s an analytical task. There are planning tasks in the 100 series, but actually, some of them depend on you doing Task 201 because you can’t work out how are you going to manage something until you’ve got some idea of what you’re dealing with. We’ll come back to that in later lessons.

It is a list of potential hazards that we’re after, and we’re trying to do it early in development. And I really can’t over emphasize how important it is to do these things early in development, because we need to do some work early on in order to set expectations, in order to set budgets, in order to set requirements and to basically get a grip, get some scope on what we think we might be doing for the rest of the program. this is a really important task and it should be done as early as possible, and it’s okay to do it several times. Because it’s an early task it should be quick, it should be fairly cheap. We should be doing it just as soon as we can when we’re at the conceptual stage when we don’t even have a proper set of requirements and then we redo it thereafter maybe. And maybe different organizations will do it for themselves and pass the information on to others. And we’ll talk about that later as well.

the task description. It says the contractor shall – actually forget about who’s supposed to do it, lots of people could and should be doing this as part of their project management or program management risk reduction because as I said, this is fundamental to what we’re doing for the rest of the safety program and indeed maybe the whole project itself. So, what we need to do is “examine the system shortly after the material solution analysis begins and compile a Preliminary Hazard List (PHL) identifying potential hazards inherent in the concept”. That’s what the standard actually says.

A couple of things to note here. Saying that you start doing it after material solution analysis has begun might be read as implying you don’t do it until after you finish doing the requirements, and I think that’s wrong, I think that’s far too late. to my mind, that is not the correct interpretation. Indeed, if we look at the last four words in the definition, it says we’re “identifying potential hazards inherent in the concept”. that, I think, gives us the correct steer. we’ve got a concept, maybe not even a full set of requirements, what are the hazards associated with that concept, with that scope? And I think that’s a good way to look at it.

Historical Review

This task places a great deal of emphasis on the review of historical documentation, and specifically on reviewing documentation with similar and legacy systems. an old system, a legacy system that we are maybe replacing with this system but there might be other legacy systems around. We need to look at those systems. The assumption is that we actually have some data from similar and legacy systems. And that’s a key weakness really with this, is that we’re assuming that we can get hold of that data. But I’ll talk about the issues with that when I get to my commentary at the end.

We need to look at the following (and it says including but not limited to).

a) mishap and incident reports, this is a US standard. they talk about mishaps because they’re trying to avoid saying accidents because that implies that something has gone wrong accidentally. Whereas the term mishap, I believe, is meant to imply that it might be accidental, it might be deliberate, whatever it might be, it doesn’t matter, something has gone wrong. An undesirable event has happened, it’s a mishap. we need to look at mishap and incident reports. Well, that’s great, if you’ve got them if they’re of good quality.

b) You need to look at hazard tracking systems. When the Mil-Std talks about hazard tracking systems it is referring to what you and I might describe as a hazard log or a risk register. It doesn’t really matter what they called, where are you storing information about your hazards? And indeed, the tracking implies that they are live hazards, in other words, associated with a live system and things are dynamic and changing. But don’t worry about that, you should, we should, be looking in our hazard logs, in our risk registers, that kind of thing.

c) Can we look at lessons learned? Fantastic, again, if we’ve got them. But unfortunately, learning lessons can be a somewhat political exercise, unfortunately. it doesn’t always happen.

d) We need to look at previous safety analyses and assessments. That’s fantastic. If we’ve got stuff that’s even halfway relevant, maybe we could use it and save ourselves a lot of time and trouble. Or maybe we could look at what’s around and go, actually, I think that’s not suitable because…, and then even that gives you a steer to say, we need to avoid what’s gone wrong with the previous set of analysis. But hopefully without just throwing them out and dismissing them out of hand, because that’s far too easy to do (not invented here, I didn’t do it, therefore it’s no good). Human pride is a dangerous thing.

e) It says health hazard information. Maybe there are some medical results, some toxicology, maybe we’ll be tracking the exposure of people to certain toxins in similar systems. What can we learn from that?

f) And test documentation. let’s look at these legacy systems. What went right, what didn’t go right and what had to be done about it. all useful sources of information.

g) And then that list continues. Mil-Std 882 includes environmental impact, its safety, and environmental impact is implicit all the way through the standard. we also need to look at environmental issues, thinking about system testing, training, where it’s going to be deployed, and maintenance at different levels. And we talk about potential locations for these things because often environmental issues are location sensitive. doing a particular task in the middle of nowhere in a desert, for example, might be completely harmless, doing it next to a significant watercourse, which is near a Ramsar Wetland (an environment of international importance) or an area of outstanding natural beauty or a national park, something like that, might have very different implications. it’s always location-sensitive with environmental stuff.

h) And being an American publication, it goes on to give a specific example: The National Environmental Policy Act (NEPA), which is in the U.S. and then similarly there is an executive order looking at actions by the federal government when abroad and how the federal government should manage that. Now, those are U.S. examples. If you’re not in the U.S. there’s probably a local equivalent of these things. And certainly, I live and work in Australia, we have an Australian Environmental Protection and Biodiversity Conservation Act (AEPBC), and that equivalent of it, it doesn’t just apply in Australia, it also applies to what the Commonwealth Government does abroad as well. outside the normal Australian jurisdiction, it does apply.

i) And then finally, we’ve got to think about disposing of the kit. Demilitarisation: maybe we’re going to take out the old military stuff and flog it to somebody, we need to think about the safety and environmental impacts of doing that. Or maybe we’re just going to dispose of the kit, whatever it might be, we’re going to scrap it or destroy it or put it away somewhere, store it again in the desert somewhere for a rainy day. If that’s not a contradiction in terms. we’re going to think about the disposal of it as well and what are the safety and environmental implications of doing so? there’s a good, broad checklist here to help us think about different issues.

Recording Results

It says that, whoever is doing this stuff, the contractor, shall document identified hazards in this hazard tracking system, in this hazard log, this risk register, whatever you want to call it. And the content of this recording and the formats to be used have got to be agreed between, it says the contractor and the program office, but generally the purchaser and whoever is doing the work. the purchaser might also be the ultimate end-user, as is often the case with the government, or it might be something else. Again, it might be the purchaser who will sell on to an end-user, but they’ve got to agree what they’re going to do with the contractor.

And of course, doing so, you’ve got to understand what your legal obligations are. Again, for example, in Australia, the WHS Act puts particular obligations on designers, manufacturers, suppliers, importers, etc. There are three duties and two of them are associated with passing on information to the end-user. be aware of what your obligations are, the kind of information that at a minimum you must provide, and probably make sure that you’re going to get, that minimum information in a usable format and maybe some other stuff as well that you might need. And it says unless specified elsewhere, in other words, by agreement with the government or whoever is the purchaser, you’ve got to have a brief description of the hazard and the causal factors associated with each identified hazard.

Now this is beginning to get away from just a pure list, isn’t it? it’s not just a list, we have to have a description that we can scope out the hazard that we’re talking about. Bear in mind, early on we might identify a lot of hazards that subsequently actually turn out to be just one hazard or are not applicable or are covered by something else. we need a description that allows us to understand the boundaries of what we’re talking about. And then we’re also being asked to identify causes or causal factors. maybe circumstances, what could cause these things, etc. it’s a little bit more than just a list, but we’re beginning to fill in the fields in the hazard log as we do this at the start.


Now, this is very useful, in the standard for every task it says here are the details to be specified in the contractual documentation, and notice it says details to be specified in the Request for Proposal. you’ve got to ask for this stuff if you need it. You’ve got to know that you need it and why you need it and what you’re going to do with the information as a purchaser. And you’ve got to put that in right at the start in the Request for Proposal and the Statement of Work. And here’s some guidance on what to include.

The big point here is this needs to be done very early on. In fact, to be honest, the purchaser is going to have to do Task 201 themselves and maybe some other tasks in order to get enough data and enough understanding to write the Request for Proposal and the Statement of Work in the first place. you do it yourself and then maybe you do a quick job to inform your contracting strategy and what you’re going to do and then you get the contractor to do it as well.

What have we got to include? Well, we’ve got to impose Task 201. I’ve seen lots of contracts where they just say, ah, do safety, do safety in accordance with this standard, do Mil-Std 882, or whatever it might be. And a very broad open-ended statement like that is vulnerable to interpretation because what your contractors, your tenderers, will do is in order to come in at the minimum price and try and be competitive is they will tailor the Mil-Std and they will chop out things that they think are unnecessary, or that they can get away without doing and they might chop out some stuff that actually you find that you need. That can cause problems.

But even worse, if you’ve got a contractor who doesn’t understand how to do system safety engineering, who doesn’t understand Mil-Std 882, they might just blindly say, oh, yeah we’ll do that, and the classic mistake is you get in the contract, it says do Mil-Std 882E and here are all the DIDs, data item descriptors which describe what’s got to be in the various documents that the contractor has to provide. And of course, government projects love having lots of documentation, whether it’s actually helpful or not.

But the danger with this is this can mislead the contractor because if they don’t understand what a system safety program is, they might just go, I’ve got to produce all these documents, yeah, I can do that and not actually realize that they’ve got to do quite a lot of analysis work in order to generate the content for those reports. And I know that sounds daft, but it does happen, I’ve seen it again and again. You got a contractor who produces these reports that on paper have met the requirements of the DID because it’s got all the right headings, it’s got all the right columns, or whatever else. But it’s full of garbage information or TBD or stuff that is obviously rubbish. And you think, no, no, you actually have to specify, you need to do the task and the documentation is the result of the task. we don’t want the tail wagging the dog. Anyway, I’ll get off my soapbox. You’ve got to impose the task, it’s a job to be done, not just a piece of paper to be produced.

Identification of the functional disciplines to be addressed. who’s going to be involved? What are you including? Are you including engineering, maintenance, human factors? Who’s got to be involved? Ideally, you want quite a wide involvement, you want lots of stakeholders, which you need to think about.

Guidance on obtaining access to government information. Now, whether it’s the government or whoever the purchaser is, it doesn’t have to be a government, getting a hold of information and guidance out of the purchaser can be very difficult. And very often that’s because the purchaser hasn’t done their homework. They haven’t worked out what information they will need to provide because maybe they don’t understand the demands of the task or they’ve just not thought it through, quite frankly. And the contractor or whoever is trying to do the analysis finds that they are hamstrung, they can’t actually do the work without the information provided by the purchaser.

That means the contractor can’t do the work, and then they just pass the risk straight back to the government, back to the purchaser, and say: I need this stuff. And then the purchaser ends up having to generate information very quickly at short notice, which is never good, you never get a quality result doing that. And often my job as a consultant is I get called in by the purchaser as often as I do by the supplier to say help, we don’t know what’s going on here, the contractor has said I can’t do the safety program without this information and I don’t understand what they want or what to tell them. as a consultant, I find myself spending a lot of time providing this kind of expertise because either the purchase or contractor doesn’t understand their obligations and hasn’t fulfilled them. Which is great for me, my firm gets paid a lot of money. It’s not good for the safety program.

Content and format requirements. Yes, we need to specify the content that we need. I say need not want. What are we going to do with this stuff? If we’re not going to do anything with it, do we actually need it at all? And what’s the format requirements? Because maybe we need to take information from lots of different subcontractors and put it all together in a consistent risk register. if it comes in all different formats, that’s going to make a lot more work and it may even make merging the information impossible. we need to think about that.

Now, what’s the concept of operations? We’ll come back to that in later tasks. But the concept of operations is, what are we going to do with this system? that should provide the operating environment. It should provide an overview of some basic requirements, maybe how the system will interface with other systems, how it will interact, concepts of operation deployment basing, and maintenance. And maybe they’re only assumptions at this stage, but the people doing the analysis will need this stuff. You recall the environmental stuff is very location-sensitive, we need a stab at where these things will happen and we need to understand what the system is going to be used for because in safety, context is everything. A system that might be perfectly safe in one context, if it’s being used not for what it was originally designed for or conceived for, can become very dangerous without anybody realizing.

Other specific hazard management requirements. What definitions are we using? Very important because again, it’s very easy to get different information that’s being generated against different definitions by different contractors. And then it’s utter confusion. Can we compare like with like, or can’t we? What risk matrix are we going to use on this program? What normally happens on 882 programs is people just take the risk matrix out of the standard and use it without changing it. Now, that might be appropriate in certain circumstances, but it isn’t always. But I’m going to talk about that, that’s a very complex, high-level management issue and I’m going to be talking about that in a separate issue about how do we actually derive a suitable risk matrix for our purposes and why we should do so. Because the use of an unsuitable matrix can cause all sorts of problems downstream, both conceptual problems in the way that we think about stuff and lower levels, sort of mechanistic problems. But I don’t have time to go into that here.

Then references and sources of hazard identification. This is another reason why the purchaser needs to have done their homework. Maybe we want the contractor or whoever is doing the analysis to look at particular sources of information that we consider to be relevant and necessary to consider. we need to specify that and understand what they are. And usually we need to understand why we want them as well.


That’s what was in the standard, as you see it’s very short, is only a page and a half in the standard and it is quite a light, high-level definition of the task because it’s an early task. Now let’s add some value here. Task 201 goes talks all about historical data. However, that is not the only way to do preliminary hazard identification. There are in fact two other classic methods to do PHI. One is the use of hazard checklists and you can also use some simple analysis techniques. And we need to remember that this is preliminary hazard identification, we’re doing this early and often to identify as many hazards as possible to find those hazards and the associated causes, consequences, maybe some controls as well. we’re trying to find stuff, not dismiss it or close out the hazards. And again, I’ve seen projects where I’ve read a preliminary hazard identification report and it says, we closed 50 hazards, and I think, no, you didn’t, you weren’t supposed to close anything because this is preliminary hazard identification. You identify stuff and then it gets further analyzed. And if upon analysis, you discover actually this hazard is not relevant, it cannot possibly happen, then, and only then, can you close it. Let’s remember, this is a preliminary hazard ID.

Commentary – Historical Data

First of all, let’s look at historical data. And first of all some issues with using this historical data, availability. Can we actually get hold of it? Now, it may be that you work for a big corporate or government organization that for whatever reason has good record keeping and you’ve got lots and lots of internal data that is of good quality that you’re allowed to access and that you know about and you can find or discover. If you are one of those people who are very, very lucky, you are in a minority, in my experience. If you’ve got all that stuff, fantastic, use it. But if you haven’t or if the information is of poor quality or people won’t give you access for whatever reason. And there are all sorts of reasons why people want to conceal information, they’re frightened of what people may discover, especially safety engineers. You may have to go out to external sources.

Now, the good news is that in the age of the Internet, getting hold of external data is extremely easy. there’s lots of potential sources of data out there, and it may range from stuff on Wikipedia, public reporting of accidents and incidents by regulators or by trade associations or by learned societies that study these things or by academics or by consultancy such as the one that I work for. there’s all kinds of potential sources of information out there that might be relevant to what you’re doing. And even if you’ve got good internal information, it’s probably worth searching out there for what’s external as a due diligence exercise, if nothing else, just to show that you haven’t just looked inwardly, that you’ve actually looked outwardly the rest of the world. There are lots of good sources of information out there. And depending on what industry you’re in, what domain you work in, you will probably know some of the things that are relevant in your area.

Now, just because data is available doesn’t mean that it’s reliable. It might be vague or inconsistent. We’ll come onto that later. It might be patchy. It’s usual for incidents to be underreported, especially minor incidents. you will find often that the stuff that gets reported is only the more serious stuff, and you should really assume that there has been under-reporting unless you’ve got a good reason not to. But to be honest, underreporting is the norm almost everywhere. there’s the issue of reliability, the data that you’ve got will be incomplete.

Secondly, another big issue is consistency. People might be reporting mishaps or incidents or accidents or events or occurrences. They might be using all sorts of different terminology to describe stuff that may or may not be relevant to what you’re talking about. And there’s lots of information out there, but actually, how has it been classified? Is it consistent? Can you compare all these different sources of information? And that can be quite tricky. And very often because of inconsistencies in the definition of a serious injury, for example, you may find that all you can actually compare with confidence is fatalities because it’s difficult to interpret death in different ways. As a safety engineer, frequently I start with fatal accidents, if there are any, because those can’t be misinterpreted. And then you start looking at serious injuries, minor injuries, incidents where no one gets hurt, but somebody could have been. There are all sorts of pitfalls with the consistency of the data that you might get a hold of.

There’s relevance. It may be that you’re looking at data from a system that superficially looks similar to yours, but with a bit of digging, you may discover that although the system was similar, it’s being used in a completely different context and therefore there are significant differences in the reporting and what you’re seeing. there may be data that is out there, but just not relevant for whatever reason.

And finally, objectivity. Now, this is a two-way street. Historical data is fantastic for objectivity because it stops people from saying subjectively, this couldn’t possibly happen. And I’ve heard this many times, you come up with something and somebody said, oh that couldn’t possibly happen, and then you show them the historical evidence that says, well it’s happened many times already and then they have to eat their words. Historical data is fantastic for keeping things objective, provided of course, that it’s available, reliable, consistent, and relevant. you’ve got to do a bit of work to make sure that you’re getting good data, but if you can, it’s absolutely worth its weight in gold, not just for Hazard I.D., but for torpedoing some of the stupid things that people come out with when they’re trying to stop you doing your job for whatever reason. historical data is great for shooting down prejudice is basically what I’m saying. reality always wins. That’s true in safety in the real world and in the safety analysis.

Having said all that, what’s the applicability of historical data? It may be that really we can only use it for preliminary hazard identification and analysis. (I’ve just noticed I’ve got preliminary hazard identification and analysis.) Sometimes I see contractors try to use historical data to say, that’s the totality of my safety argument, my kit is wonderful, it never goes wrong and therefore it will never go wrong, that’s the totality of my safety argument. And that never works, because when you start trying to use historical data as the complete safety argument, you very quickly come up against these problems of availability, reliability, consistency, and relevance.

It’s almost impossible to argue that a future system will be safe purely because it’s never gone wrong in the past. And in fact, trying to make such claims as, it’s never gone wrong, we’ve never had a problem, we’ve never had an incident, straight away that would suggest to me that they don’t have a very good incident reporting system or that they’ve just conveniently ignored the information they do have and not that people selling things ever do anything like that? Of course, no, never. There’s a lot of used car salesmen out there. probably this use of historical data, we might have to keep it fairly limited. It might be usable for preliminary work only. And then we have to do the real work with analysis. But almost certainly it’s not going to be the whole answer on its own. do bear that in mind, historical data has its limits.

It’s also worth remembering that we get data from people as well. In Australia, the law requires managers to consult with workers in order to get this kind of information. No doubt in other countries there are similar obligations. there’s lots of people out there, potentially workers, management, suppliers and users, maintainers, regulators, trade associations, lots of people who might have relevant information. we really ought to consult them if we can. Sometimes that information is published, but other times we have to go and talk to people or get them to come to a preliminary hazard I.D. meeting in order to take part. There are lots of good ways of doing this stuff.

Commentary – Hazard Checklists

Let’s move on to hazard checklists. Checklists are great because someone else has done the work for you to a degree that it’s quick and cheap to get a checklist from somewhere and go through it to see if you can find anything that prompts you to go, yeah that could be an issue with my system. And the great thing about checklists is they broaden the scope of your hazard I.D. because if your historical data is a bit patchy or a bit inconsistent as it often is, it will identify some stuff, but not everything. the great thing about a checklist is very often broad and shallow, it really broadens the scope of the hazard I.D., it complements your historical data. I would always recommend having a go with a checklist.

Now, bear in mind that checklists tend to identify causes, you then have to use some imagination to go, okay, here’s a cause, how in the context of my system, how in the context of this concept of operations (very important), in this context, how could that cause lead to a hazard and maybe to a mishap? you need to apply some imagination with your checklist and it can be a good way of prompting a meeting of stakeholders to think about different issues because people will turn up with an axe to grind, they’ll have their favourite thing they want to talk about. Having a checklist keeps it objective or having historical data to review, keep it objective, and keeps people on track, so they don’t just go down a rabbit hole and never look at anything else.

But again, this is preliminary hazard identification only. if something comes up, I would advise you to take the position that it could happen unless we have evidence that it could not. And notice, I say evidence, not opinion. I’ve met plenty of people who will swear blind, that such and such could not possibly happen. A classic one that suckered me, somebody said no British pilot would ever be stupid enough to take off with that problem, and like a fool, I believed them. Don’t listen to opinion, however convincing it is unless there’s evidence to say it cannot happen because it will. And in that case, it did two weeks later. don’t believe people when they say, oh that couldn’t possibly happen, it just shows a lack of imagination. Or they’ve got some vested interests and they’re trying to keep peace and keep you away from something.

It’s worth mentioning, in Australia at minimum, we need to use the approach for Hazard I.D. that is in the WHS Risk Management Code of Practice. there’s some good basic advice in that code of practice on what to do to identify and analyse hazards and assess risks and manage them. We need to do it, at minimum. It’s a good way to start, and in fact there’s a bit of a hazard checklist in there as well. It’s not great, it’s workplace stuff mainly rather than design stuff or systems engineering stuff. But nevertheless, there’s some good stuff in there and that is the absolute bare minimum that we have to do in Australia. And there will probably be local equivalents wherever you are.

If you’re looking for a good example for a general checklist, if you look in, the U.K.’s ASEMS, which is the MOD acquisition safety and environmental management system. In POSMS, which is the project-oriented safety management system, there is a safety management procedure, SMP04, which is PHI. And that’s got a checklist in there. It’s aimed at sort of big equipment, military equipment, but there’s a lot of interesting stuff in there that you could apply to almost anything. If you look online, you’ll probably find lots of checklists, both general checklists and specialist checklists for your areas, maybe your trade association, or whatever has a specialist checklist for the particular stuff, the thing that you do. always good to look up those things online, and see if you can access them and use them. And as I say, using multiple techniques helps us to ensure or have confidence that we’ve got fairly complete coverage, which is something that we’re going to need later on. And dependent on your regulator, you might have to demonstrate that you’ve done a thorough job, using multiple techniques is a good way of doing that. I’ve already said checklists nicely complement historical data because they’ve got different weaknesses.

Commentary – Analysis Technique

A third technique, which again takes a different approach, it complements the other two, is to use some kind of analysis technique to identify hazards. And there are lots of them out there. Again, I’m not going to go into them now in this session, I’m just going to give you one example, which is probably the simplest one I know, and therefore the most cost-effective. And you can do this as a desktop exercise and then get some stakeholders in and do it live with the stakeholders. Either use what you’ve prepared, or keep what you’ve prepared in your back pocket if you need to get things going, if people are stumped, they’re not sure what to do.

Now, this technique I’m just going to talk about is called Functional Failure Analysis (FFA). And really all it does, you take a basic top-level function of whatever it is that you’re considering, you’ve got your concept of operations that says, I need a system to do X, Y, Z, you go, let’s look at X, Y, and Z, and with each one of these functions, what happens if it doesn’t work when it’s supposed to work, or what happens if it works when I don’t want it to? That’s the un-commanded function or unwanted function, maybe. And then what if it happens, but it doesn’t happen completely correctly. What if it happens incorrectly? And there might be several different answers to that.

I’ll give you an example. Let’s assume that you’re Mr. Mercedes, and you’re inventing the horseless carriage, you’re inventing the automobile, the car. And you say, this thing, it’s got a motor, I wanted it to start off, I want it to go and then I want to stop. those really, really simple conceptual ideas, I want it to go, or I want it to start moving. What happens if it doesn’t? Well, nothing actually, from a safety point of view. The driver might be a bit frustrated, but it’s not going to hurt anybody. Next, an un-commanded function: what if it goes when it’s not supposed to? Now that’s bad. Or maybe the vehicle will roll away downhill when it’s not supposed to. We need a parking brake, in that case, we need a handbrake or use chocks or something or we restrain it.

Straight away, with something as simple and simplistic as this, you can begin to identify issues and say, we need to do something about that. this is a really powerful technique, you get a lot of bangs per buck. And then, of course, we could go on with the example, it’s a trivial example, but you can see potentially how powerful it is providing you’re prepared to ask these open-ended questions and answer them imaginatively without closing your mind to different possibilities. there’s an example of an analysis technique, and again, remember that this preliminary hazard ID. If we’ve identified something that could happen, then it could happen unless we have evidence that it could not.

I’ve talked for long enough, it just remains for me to point out that the quotations from Mil-Std are copyright free. But this video is copyright of The Safety Artisan 2020. And you can find more safety information, more lessons, and more safety resources at I just want to say that’s the end of the lesson, thank you very much for listening and I hope you’ve found today’s session useful. Goodbye.

End: Preliminary Hazard Identification

You can find a free pdf of the System Safety Engineering Standard, Mil-Std-882E, here.

Leave a Reply

Your email address will not be published. Required fields are marked *