Tag Archives: Miller’s Formula For Risk

Understanding Risk, Hazards and Mishap Prevention

It is critical to understand the terms risk and hazard.

A hazard is a something that causes danger such as an incomplete or outdated procedure, an object such as a equipment, a malfunction or a human factor. The hazard is real, it is perceivable and most of all discoverable BEFORE any mishap, accident or incident occurs.

This is a CRITICAL part of safety theory. A Hazard is a real thing and certain people with a good safety eye can see it ahead of any accident. Some do not, but many do and can report that hazard to the safety manager, who if he or she is smart enough, can take steps to eliminate that hazard.

Why is it important to eliminate hazards?????

Safety theory says that mishaps, accident and incidents are the result of unresolved hazards. That is the sole purpose of safety investigations: identify the hazard and eliminate them.

But if you seek mishap free operations, then you have to go seek out hazards and eliminate them ahead of time. If you do that, you will enjoy mishap free operations.

A risk is defined as a product of two factors. First factor is the likelihood of the event occurring on a sliding scale from zero to 100. Think of this as a per cent of probability which could be measured from a low of very unlikely, at or near zero per cent, then all the way up to very likely, that is at or near 100%.
The second factor is the severity of the event if it occurs. This means if the hazard does occur, what are the consequences? How badly will a plane be destroyed if it crashes, how seriously will a person be injured or will they die, how severely will equipment be damaged or destroyed? You could assign a numerical value to severity as well on a sliding scale of zero to 100 percentage, meaning that none, some or all of the aircraft, person, property or equipment is damaged, injured, destroyed or killed.

When you multiply the two factors of probability per cent and severity per centage together, the product becomes RISK, which is a real number. Risk is a product of two factors, meaning that each is factor is multiplied together to form a number. As when multiplying any two numbers between zero and 100 together, the product increases rapidly and in a hyperbolic fashion.

So I have written a mathematical formula to describe this and it is called, MILLER’S FORMULA FOR RISK. RIsk is labled Z, Probability is labeled X and Severity is labeled Y. When you multiply probability by severity you come up with risk. So the formula looks like this Z=XY. Plotting this function gives you a three dimensional display of the full range of risks. Factor in several more factors such as time and resources devoted to mishap investigations, called factor N and take into account some level of periodocity by looking at the trigonometric sine function and MILLER’S FORMULA FOR RISK becomes Z= sine |X| N(Y).

There is more in my paper published in the Flight Safety Foundation Proceedings of the 2003 Corporate Aviation Safety Seminar, entitled “Forecasting Hazards and Charting a Safe Course: How to Plan Changes in Flight Safety Programs to Meet Future Safety Issues, Decisions and Attitudes, and Keep Your Business Profitable!” copyrighted 2003.

If you have any problem getting a copy or a copy of the accompanying Powerpoint or would like me to come to your organization to speak more on this subject, contact me by Paulmiller@safetyforecast.com.

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