Introduction to Health and Safety at Work

Promoting a positive health and safety culture
57
may be reduced by re-designing equipment so that, 
for example, an audible horn indicates the omission of 
a task. They may also be reduced signifi cantly by the 
use of detailed checklists.
Mistakes
Mistakes occur when an incorrect action takes place but 
the person involved believes the action to be correct. 
A mistake involves an incorrect judgement. There are two 
types of mistakes – rule-based and knowledge-based.
Rule-based mistakes occur when a rule or procedure 
is remembered or applied incorrectly. These mistakes 
usually happen when, due to an error, the rule that is 
normally used no longer applies. For example, a particu-
lar job requires the counting of items into groups of ten 
followed by the adding together of the groups so that 
the total number of items may be calculated. If one of 
the groups is miscounted, the fi nal total will be incorrect 
even though the rule has been followed.
Knowledge-based mistakes occur when well-tried 
methods or calculation rules are used inappropriately. 
For example, the depth of the foundations required for 
a particular building was calculated using a formula. 
The formula, which assumed a clay soil, was used to 
calculate the foundation depth in a sandy soil. The result-
ant building was unsafe.
The HSE has suggested the following points to 
consider when the potential source of human errors are 
to be identifi ed:
➤
What human errors can occur with each task? There 
are formal methods available to help with this task
➤
What 
infl uences are there on performance? Typical 
infl uences include, time pressure, design of controls, 
displays and procedures, training and experience, 
fatigue and levels of supervision
➤
What are the consequences of the identifi ed errors? 
What are the signifi cant errors?
➤
Are there opportunities for detecting each error and 
recovering it?
➤
Are there any relationships between the identifi ed 
errors? Could the same error be made on more than 
one item of equipment due, for example, to the incor-
rect calibration of an instrument?
Errors and mistakes can be reduced by the use of instruc-
tion, training and relevant information. However, com-
munication can also be a problem, particularly at shift 
handover times. Environmental and organizational factors, 
involving workplace stress will also affect error levels.
The following steps are suggested to reduce the 
likelihood of human error:
➤
examine and reduce the workplace stressors (e.g. 
noise, poor lighting, etc.) which increase the fre-
quency of errors
➤
examine and reduce any social or organizational 
stressors (e.g. insuffi cient staffi ng levels, peer pres-
sure, etc.)
➤
design plant and equipment to reduce error pos-
sibilities – poorly designed displays, ambiguous 
instructions
➤
ensure that there are effective training arrangements
➤
simplify any complicated or complex procedures
➤
ensure that there is adequate supervision, particu-
larly for inexperienced or young trainees
➤
check that job procedures, instructions and manuals 
are kept up to date and are clear
➤
include the possibility of human error when under-
taking the risk assessment
➤
isolate the human error element of any accident or 
incident and introduce measures to reduce the risk 
of a repeat
➤
monitor the effectiveness of any measures taken to 
reduce errors.