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ARCH.070 Calculate system deviation probability

SM-2812 - Populate Confluence page for activity definition: ARCH.070 Calculate system deviation probability IN PEER REVIEW

GoalCalculate system deviation probabilities taking into account identified system level deviations and safety measures.
Requirements met by this process step

EN 50126-1 6.3.3.1, 6.3.3.2, 6.3.3.3

ISO 15288 6.4.3.3 e)

InputsAMOD-004 Fault tree (per operational deviation)
OutputsAMOD-004 Fault tree (per operational deviation) (updated)
Methodology

Following prerequisite activities have been completed in ARCH.067ARCH.068 and ARCH.069:

  • Initial fault tree has been populated per operational capability
  • System level deviations of external incoming functional exchanges have been assessed and are reflected in the fault tree
  • Additional safety measures have been added to compensate for deviations of incoming functional exchanges that are of low safety integrity


In this activity the overall system level deviation probabilities shall be calculated, taking into account the aforementioned activities (initial fault tree, assessed deviations of external functional exchanges, additional safety measures).

The result shall be be compared to the probability of the caused operational deviation:

  • If the probability of the caused operational level deviation is not exceeded by the calculated system level probability this process activity is completed.
  • If the probability of the cause operational level deviation is exceeded by the calculated system level probability this predecessor process activities shall be repeated, starting at ARCH.068.


Tools and non-human resources

Team for Capella

(tbd - possibly a further tool or plugin for modelling fault trees - ticketed SET-183

CardinalityOnce, with allowed revisions after changes in the operational level risk model or the system function definitions or after additional safety measure. 
Completion criteriaOverall system level deviation probability does not exceed the caused operational level deviation probability.
Design reviewARCH.R.3 System capability review
Step done by (Responsible)

RAMS architect

Security architect

Provides input to/assists (Contributes)

System architect

Uses outputs (Informed)None identified.