In their publication “Reducing Error and Influencing Behaviour” HS (G) 48, the HSE identifies two distinct types of human failure and these are:
- Human Error
a) Human Error
Human error may be defined as a failure, on the part of the human operator, to perform an assigned task within specified limits of tolerance, with such limits generally being defined in terms of accuracy, sequence or time.
Factors that can contribute to human error may be considered under the headings of :
- Lapses of attention
- Mistaken actions
- Mistaken priorities
- Inadequate design
- Inadequate information
Slips are failures to carry out the actions of a task or actions not as planned, such as:
- Performing an action too early or too late in a procedure
- Omitting steps or a series of steps from a procedure
- Turning a control knob in the wrong direction
- Doing the right thing on the wrong object
- Reading the wrong dial
2) Lapses of Attention
Lapses cause us to forget to carry out or complete an action or even to forget what we set out to do and these are common when there is long period of waiting and/or tasks take a long time to complete. Competing demands for (limited) attention, faltering concentration due to tiredness or routine monotonous jobs may also be factors.
An experienced road tanker driver had virtually completed the filling of his vehicle from a bulk of flammable liquid when a nearby telephone rang. He ignored the phone for approx 5 minutes until the tanker was loaded then he closed the valves on the installation and went to answer the phone. Upon returning to the vehicle he drove away having forgotten that he had not disconnected the tanker hose from the installation and damaged fixed pipe work.
(Get the full part of this Syllabus from the June Issue of Safety Messenger 2015)