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High Integrity Systems & Software   

In relation to Safety, software cannot be treated as an independent entity: software forms an integral part of the majority of complex systems.  Many Standards, such as IEC 61508, require that the required safety integrity levels (SILs) for safety functions are derived on the basis of risk assessment at the system level.  This has to be carried out before the design of the safety-related system, because the required SIL has a significant impact on the design/development process.  The required SIL will affect the design requirements for hardware and software safety integrity (e.g. reliability, fault tolerance, software methods) as well as having an impact on more general aspects such as functional safety management and assessment.


Safety Assurance Services have a thorough understanding and familiarity with the standards and assurance process for High Integrity / Safety Related Systems.  The term ‘Safety-Related System’ (SRS) denoting a combination of hardware, electronics, software and people that together operates in response to its inputs to ensure safety.  We can support your organisation in areas such as:   

  • Assessment of the appropriate SIL for software, based on a system level assessment   

  • Assisting in defining appropriate design techniques and methods relevant to the assigned SIL   

  • Auditing the development lifecycle and software against the required SIL   

  • Advice on approach to assurance for previously developed software or modification to legacy software or COTS software 

  • Independent Software Safety Auditor role

  • Development of Software quality procedures 



© Safety Assurance Services Limited, Pinons, Dene Close, Lower Bourne, Farnham, Surrey, GU10 3PP  Tel: 01252 758023