Identify and Analyze Functional Hazards

So, how do we identify and analyze functional hazards? I’ve seen a lot of projects and programs. We’re great at doing the physical hazards, but not so good at the functional hazards.

So, when I talk about physical and functional hazards, the physical stuff, I think we’re probably all very familiar with them. They’re all to do with energy and toxicity.

Physical Hazards

So with energy, it might be fire, it might be electric shock. Potential energy, the potential energy of someone at height, or something falling. The impact of the kinetic energy. And then of course, in terms of toxicity, we’ve got hazardous chemicals, which we have to deal with. And then we’ve got biological hazards, plus smoke and toxic gasses, often from fires. Or chemical reactions.

So those are your physical hazards. As I said, we tend to be good at dealing with those. We’re used to dealing with that stuff. And most projects I’ve been on have been pretty good at identifying and analyzing that stuff. Not so for functional hazards.

Functional Hazards

I’ve been on lots of projects still today where functional hazards are just ignored completely or they’re only dealt with partially. So let’s explain what I mean about functional hazards. What we’re talking about is where a system is required to do something to perform some function. For example, cars move. They start, they move and they stop, hopefully.

Loss of Function

But what happens when those functions go wrong? What happens when we don’t get the function when we need it? The brakes fail on your car, for example. And so that’s a fairly obvious one. When functional hazards are looked at, it’s usually the functional failures that get attention.

But if that is the obvious failure mode, the less obvious failure modes tend to be more dangerous and there are the two.

Other Functional Failure Modes

So what happens if things work when they shouldn’t? What if you’re driving along on a road or the motorway, perhaps at high speed, and your brakes slam on for no apparent reason? Perhaps there is somebody behind you. Do you have a collision or do you lose control on the road and crash?

What if the function works, but it works incorrectly? For example, you turn the temperature down but instead, it goes up. Or you steer to the left, but instead, your vehicle goes to the right.

What if a display shows the wrong information? If you’re in a plane, maybe you’ve got an altimeter that tells you how high you are. It would be dangerous if the altimeter told you that you were level or climbing, but you were descending towards the ground. Yeah, we’ve had lots of that kind of accident.

So there’s an overview of what I mean by physical and functional hazards.

The Webinar: Identify and Analyze Functional Hazards

See the whole webinar at the Safety Engineering Academy. (You can get discounts on membership by subscribing to my free emails.)

Course Curriculum

1. Introduction
2. Preliminary Hazard Identification (PHI)
3. Functional Failure Analysis
4. Functional Hazard Analysis (FHA)

There are 11 lessons with two-and-a-half hours of video content, plus other resources. See the Foundations of System Safety here.

Meet the Author