[SystemSafety] Software Safety Assessment

[Carl Sandom]

Consider the following scenario:

In 2004 Project A software was assessed against a safety standard (let's call it Standard X). Standard X had a very prescriptive list of software safety requirements and a simple checklist was used for assessing SIL1 compliance.

In 2014, Project B began to integrate significant new functionality into Project A. Standard X, which was by 2014 an obsolete standard, was used to assess the significantly smaller software baseline of Project B. Under modern scrutiny, the simple Standard X checklist used for Project A in 2004 was not as explicit as it could have been and it was decided to use an improved checklist for Project B.

A couple of important questions can be raised with this scenario:

1. Is it acceptable to use an obsolete safety standard to assess software?

2. Is the SIL1 claim for 10 year old Project A invalid because the checklist could have been better?

3. If Project B used the old checklist from Project A would that be adequate?

I've been having some interesting discussions with the Project Managers involved, any thoughts?

Regards
Carl

_________________________________

Dr. Carl Sandom CErgHF CEng PhD

Director

iSys Integrity Ltd.

+44 7967 672560

carl at isys-integrity.com<mailto:carl at isys-integrity.com>

www.isys-integrity.com<http://www.isys-integrity.com>

_________________________________

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