Something that always makes me pause when reviewing designs… Proof test coverage that somehow always ends up being 100% effective. On paper it looks great. The numbers work nicely. The SIL calculation passes comfortably. But in the real world I always find myself thinking: Can we really detecting every dangerous failure with that test? In my experience, this is a major cause of rework. If the design progresses to the point where commissioning documents are written and then a FSA or design review reveals overly optimistic proof test coverage it’s a lot of work to correct. Anyone else experiencing this?

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I've been struggling with this point for some time. In Automotive, ISO 26262 part 5 provides an equation to calculate the PMHF. A follow-up example explains it with numbers. My issue is: When I try to apply the same equation on the solved example in the standard, I cannot generate the same results. The main tool we use to calculate the PMHF is Medini, and it uses a completely different strategy to get it. Can someone inform me how these values are generated with the equation?

Hi all thanks for the add, this looks like a really good way to share experience in the functional safety world. Thanks for setting up Richard. I have a question for you all on the requirements when adding a new SIF to an existing SIL2 system that was designed over 40 years ago and was never designed to 61508. What things would we consider to make this possible without a full system redesign.

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