439 / 975
Functional Safety 2014
4
th
– 5
th
November 2014
Copyright © 2014 by Cenbee Bullock PFS Consulting Ltd
Page 9 of 14
“Human error problems can be viewed in two ways: the person approach and the system
approach.
The person approach focuses on the errors of individuals, blaming them for forgetfulness,
inattention, or moral weakness.
The system approach concentrates on the conditions under which individuals work and tries
to build defences to avert errors or mitigate their effects.”
Recognising human weakness, with a constructive attitude, and applying a systematic approach to
provide barriers to minimise systematic human failures is important for any successful operation.
Dr Nils Löber
6
states
“Without constructive error attitude, safety instruments will never unfold their full protective
potential.”
Fig. 4 shows the Swiss cheese model of human errors and mistakes through different phases of the
lifecycle. Defences and barriers to minimise the possible systematic human failures throughout the
safety lifecycle phases can be effected by applying a systematic approach and using the Safety
Management Plan (or Management of Functional Safety).
The Safety Management Plan is a live document that needs to be updated accordingly for each of the
different phases of the project. It is an overarching document and includes the safety lifecycle. It acts
as road map to provide the direction for the project in managing safety-related activities; ensuring all
safety-related activities are being executed strategically and systematically.
The structured review process and well-defined documentation system should be used as the defence
and barriers to minimise any possible systematic human failures (as illustrated in the Swiss cheese
model). These activities should be supported and monitored by a suitably qualified and experienced
management team.
The components within the Safety Management Plan should consist of all the requirements as stated
in IEC61508-1 clause 6 including:
i.
Roles and responsibilities in each phase of the safety lifecycle activities and the approved
authority;
ii.
Design review procedures through the different phases of the lifecycle;
iii.
Structured document review scheme and approval procedures (i.e. revised, reviewed and
approved – all should be clearly identified with current revision and date of completion).
iv.
Independent technical review and assessment; carried out by an independent subject matter
professional and preferably with access to the project information but not part of the design
and engineering team.
Fig. 5 shows an illustration of the safety lifecycle with the inclusion of a management procedural
system including:
i.
Safety Management Plan
ii.
Human Factor Integration Plan
iii.
Management of Change Procedure
6
Dr. Nils Löber, “Coping with (human) errors in organizational and industrial settings” 05.11.2012