Yellow Book User Group 5 Developing Yellow Book 4

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Yellow Book User Group 5Developing Yellow Book 4

• Updating Risk Management Techniques

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A look outside Rail

• European Air Traffic Management
• New Regulations e.g. SMS, TLS Safety Cases
• Continued harmonisation towards Target
  Architecture
• Military and Civil Avionics
• New technology to counter problems with
  obsolescence and increasing Whole Lifecycle Costs
• Increasing use of Commercial Off the Shelf
  components
• Desire to make Re-certification easier and cheaper

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Impact on Risk Assessment

• Objective Based Standards
• ESARRs introduce TLS and Safety Objectives
• New version of Def Stan 00-56 (say goodbye to
  SILs?)
• Target Level of Safety
• One target for all Civil airspace
• New Technology (such as IMA)
• Increases complexity of certification
• Introduces large scale integration of
  functionality
• Increased desire to use COTs

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Objective Based Standards

• Example from CAP 670 SW01

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Risk Management Methodologies

• Greater rigour in generating Safety Requirements
• Facilitates apportionment of TLS
• Ensures identification of Safety Properties as
  well as Evidence Assurance Levels
• Use of Risk Directed techniques
• Use safety properties to help define design,
  tailor development and focus certification
• Build safety cases using formal argument
  semantics
• Use of Modular Safety Cases
• To support certification of system of systems
• To ease re-certification

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Risk Directed Approach
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Building an Argument
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Modular Certification

• Establishes a basis for
• building Safety Cases for a system of systems
• incremental certification
• a more efficient re-certification process
• Based on
• self-contained Modular Safety Cases
• contracts between modules

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Benefits

• Overall approach still supports existing
  standards infrastructure and aids transition
• Provides a robust framework for
• certifying COTS, Legacy and
• products certified to other standards
• Helps to focus on what is being certified not how
  it is being certified
• Although how is still important!
• Experience to date suggests new techniques
  provide greater confidence at less cost

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Implications for YB4

• Basis for Objective Based approach already
  present in Fundamentals
• Need to consider improvements to
• Safety Requirements Engineering
• Risk Assessment Techniques
• Safety Case Construction
• Can also benefit Programme Risk Management