Assessing risk in engineering, work and life
Assessing risk in engineering, work and life

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Assessing risk in engineering, work and life

2.2 Human error

There is one more aspect to discuss in identifying the cause of accidents. Engineers can work hard at making sure they have the right designs, the right materials, the right working approaches and the right safety systems. As already highlighted, very few accidents are caused by one event or failure; there are potentially various interactive small failures, which eventually coincide to cause the event. However, there is also another consideration: the majority of accidents are caused not by materials or safety systems, but by people. This is known as ‘human error’ – that is, errors made by people rather than by equipment or systems. In fact, according to Heinrich, 80–90% of accidents are due to human error (Heinrich et al., 1980).

Similarly, an often quoted study of severe and fatal industrial accidents by Salminen and Tallberg (1996) found that 84–94% were due mainly to human error. A national survey of traffic accidents in the USA found that of over two million road accidents, some 94% were due to human error (NHTSA, 2015); only 2% were attributed to vehicles and 2% to the environment. So human error is not a trivial factor to consider.

The influence of human error in a chain of events leading up to an accident can occur despite the best training, standard operation protocols or systems available. Many major accidents were initiated by human error. For example:

  • Chernobyl, a nuclear reactor explosion in 1986 that caused around 50 immediate deaths, a currently unknown (but hotly disputed) number of future deaths and the contamination of a massive area of land (WHO, 2006)
  • Piper Alpha, a fire on a North Sea oil production platform in 1988 that caused the deaths of 167 of the 228 people on board (HSE, 2004)
  • Texas City, an oil refinery explosion in 2005 that caused 15 deaths and 180 other injuries (CSB, 2007).

As human error is difficult to eliminate completely, it is important that any design, system or approach takes this into consideration. People make mistakes, or they simply forget to do things, or sometimes they decide not to do things because they do not understand their worth.

Returning to the Deepwater Horizon disaster, the team that investigated the events concluded that a series of eight failures led to the accident. Of these eight, at least three were governed by human decisions: the results of a seal test were misinterpreted, raised flows were not identified as a leak, and there were weaknesses in the BOP testing and maintenance management system. As a result, human error was a significant contributory factor to the overall incident.

T193_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371