• BilboBargains@lemmy.world
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    9 months ago

    Safety cannot be measured because it’s a feeling. One person feels safe climbing a mountain without a rope and the next person is petrified. Safety is just word to describe a concept. It’s different to the wavelength of light or force or charge. These things are based on fundamental properties of the universe that can be measured and are repeatable.

    A reasonable approximation might be to consider the likelihood of an adverse event given a use case over time. We could say that an accident every million hours is our definition of safe but that is completely arbitrary in the way that the physical laws and constants are not.

    • Hacksaw
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      9 months ago

      One accident per million hours is a direct measurement of safety, not “completely arbitrary”. The idea that the threshold in aviation regulations are “arbitrary” because it’s not based on a physical law or constant is like saying the temperature we use as “too hot for prolonged contact” is arbitrary. If you exceed it you’re likely to get burned, and if you exceed the safety thresholds in aviation regulations you’ll be less safe in an airplane than other types of transportation that we as a society find acceptable.

      In engineering safety is not “just a feeling”.

      Your arguments are so absurd I’m certain you’re just trolling for a reaction with brain dead comments like this.

      • BilboBargains@lemmy.world
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        9 months ago

        It’s a measurement on an arbitrary scale. Nothing I’ve said is news to anyone who designs safety critical systems. I’m certainly not saying that safety isn’t important or that we can’t assess it. What I’m saying is that placing a number on that assessment will always stray into the realm of politics in a way that physics and mathematics never does. It lulls ignorant people into the belief that something is safe or not safe. They feel safe because they’ve been told it is safe or vice versa. Physics doesn’t care if you feel safe.

        It’s notable that contemporary safety standards such as ISO 26262 generally avoid numerical assessments, for the reasons outlined above.

        • Hacksaw
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          9 months ago

          First Incidents per hour is not arbitrary. These numbers compare very well to daily activities such as walking, driving, bathing, eating, swimming so that non specialists have a good idea of how much risk an activity carries by comparing it to an activity they’re familiar with.

          Secondly ISO 26262 produces ASILs as its output which are qualitative, but still based on probably assessments in terms of chance of incidence per hour. The reason for qualitative instead of quantitative assessments of the more general SILs (based on IEC61508, the parent of ISO 26262) is that qualitative is cheaper than quantitative and the automotive industry is full of corner cutting.

          Third, aircraft use QUANTITATIVE risk assessments based on ARP476, so risk can be directly measured and mathematicaly compared to any other activity. When people say “flying is safer than driving” it’s not arbitrary, it’s based on real math. The same math the FAA is using to find safety issues in the Boeing production line.

          Fourth

          I’m certainly not saying that safety isn’t important or that we can’t assess it.

          Is this you?

          safety isn’t a thing we can measure.