Those irritating 20 %

by Ed Verbeek - published on 1 June 2021 821 -

Article by Ed Verbeek, MSc, FNI

A long time ago, on an instructors course, I was taught that you should start your presentation with a BOOM, not with a 'poof'……..

In line with that, I used to start presentations on the infamous 80 % “Human Error” with:

Whenever I hear that 80 % of the accidents at sea are caused by Human Error; I am shocked.
I hope I offend no one, but I am shocked that after thousands of years of designing, building and equipping ships, the technology is apparently still so frail that one out of five accidents has technical causes.

This was closely followed by

I have sometimes heard: “80% Human Error, what are we going to do about it". Well, I have good news: if you would want to reduce it, that is very easy. Just build bad ships and put even worse equipment on board and you will see the percentage of Human Error in accidents reduce dramatically. The only downturn is that you will have to accept an increase in the number of accidents.

I have discovered that such a BOOM can be an overkill. I noticed that some people needed so much time to recover, that they missed part of the rest of the presentation. Some were taken aback, thinking that I was looking for a confrontation…

So I have developed a better sized BOOM, and hope that this is sufficient to raise your interest, without triggering negative feelings. My new start:

Just suppose you want to buy a car, and the seller notices that safety is an important issue for you. Just suppose that he will say: this is not such a good car: almost 100 % of the accidents with this car are because of “Human Error”. That other car is much safer: only 60 % of the accidents are because of “Human Error”, the other accidents are because of brakes failing, steering break-downs, etc etc. Would you agree with this seller?

In fact, what happens as soon as there is any systemic technical problem with a car? There will be a recall! In 2018, Toyota recalled more than 2,4 million Prius cars because of possible power stall in rare circumstances. Toyota declined to say if an actual accident did happen…. In road traffic we’re talking in excess of 99% "Human Error"…..and no one would want it differently. Actually we don’t even discuss it. I am quite sure that in road traffic 20% accidents due to technical failures would be absolutely unacceptable. It would be nice if we could reduce this irritating figure of 20% "Technical Failures" in shipping too! (realising that - while reducing the number of accidents - this would automatically increase the percentage "Human Error")
Technical or Human Error?
Technical or Human Error?
Technical or Human Error?
Technical or Human Error?
My hypothesis is that any mature, well developed system is bound to have a high percentage “Human Error”. As the system develops, and the reasons for technical failures are analysed, these are remedied. The number of technical failures will then reduce. On the human side, as the system develops, risks are better known, and procedures will be developed, bringing down the number of accidents due to "Human Error". However, humans will continue to have to make decisions based on incomplete information, while having to serve multiple, partly conflicting goals, in an imperfect designed and regulated environment. So it is much harder to bring down this number. The sum total is much less accidents, and as accidents attributes to technical failures reduce even more than accidents attributed to "Human Error" , the percentage "Human Error" will increase. A high percentage "Human Error" is an indication that the people at the sharp end are given tools that are 'fit for purpose'.

I like to just play with numbers to gain a better understanding of what the ramifications of statements are. Let's just do that with this statement: suppose that in a developing system there are 1000 incidents, 500 due to technical failures and 500 due to "Human Error". As the system matures, and the technical requirements are better known, adding a bit of steel here, fixing that connection, making that part a bit more resilient, brings down the number due to technical failure to 50. Better selection, training and procedures brings down "Human Error" to 150. So over the years safety increased dramatically. Accidents due to technical failures reduced from 500 to 50. Accidents due to "Human Error" reduced from 500 to 150. The total number of accidents reduced from 1000 to 200. In percentages the total number of incidents reduced by 80%, but "Human Error" has gone up from 50% to 75%(!) while technical failure reduced from 50% to 25%. Although I don't know of any research on the subject, I'm convinced that in the 17th century the percentage "Human Error" was much lower than presently, as many accidents happened because of technical failures, or uncontrollable circumstances.

By the way, although it can be assumed that mature, well developed systems have a high percentage of “Human Error”, this can not be turned around: a system with a high percentage "Human Error" does not necessarily have to be a mature, well developed system. There is always the possibility that a high percentage "Human Error" is due to insufficient selection, training, experience etc. However for a mature, regulated system it is unlikely that this would play a large part.
The message I want to bring across with this article is quite simple: Mature, well developed systems are bound to have a low percentage of technical failures. Consequently these systems will have a high percentage if Human Error. There is no need for a knee-jerk reaction to try to reduce this. Most likely it is a good sign and there is no need to reduce this percentage! We need other indicators to know what needs improvement and how that could be achieved.
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Opinion pieces reflect the personal opinion of individual authors. They do not allow any conclusions to be drawn about a prevailing opinion in the respective editorial department. Opinion pieces might be deliberately formulated in a pronounced or even explicit tone and may contain biased arguments. They might be intended to polarise and stimulate discussion. In this, they deliberately differ from the factual articles you typically find on this platform, written to present facts and opinions in as balanced a manner as possible.

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Sanjeev Pande Ocean Sparkle Limited, India
on 13 June 2021, 08:44 UTC

Spot on! In a mature system, a 20% error factor should make us start looking for, or devising, different indicators other than for "human error" if we want to reduce the error percentage any further.


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