…and the value of virtuous witnesses
I have to say that I’ve never been terribly impressed with ISO 61508, given it purports to be so arcane that it require a priesthood of independent safety assessors to reliably interpret and sanction its implementation. My view is if your standard is that difficult then you need to rewrite the standard.
Which is where I would have parked my unhappiness with the general 61508 concept of an ISA, until I remembered a paper written by John Downer on how the FAA regulates the aerospace sector. Within the FAA’s regulatory framework there exists an analog to the ISA role, in the form of what are called Designated Engineering Representatives or DERs. In a similar independent sign-off role to the ISAs, DERs are paid by the company they work for to carry out a certifying function on behalf of the FAA.