What do safety standards say about this?
Where formal methods appear
| Standard | Domain | Where formal methods sit |
|---|---|---|
| IEC 61508 | Functional safety (general) | Highly recommended at SIL 4 |
| EN 50128 | Railway | Highly recommended at SIL 3 and 4 |
| ISO 26262 | Automotive | Recommended |
| DO-178C | Aerospace | A separate supplement, DO-333, sets out how to apply formal methods |
This restates the company’s own article. It is not a substitute for the standards.
What that means for people who build equipment
- For ordinary factory-automation equipment, no standard today makes formal methods mandatory. The company says so itself.
- The standards are worth reading as a signal of where the difficulty lies: four independently written standards reach for the same technique once the hazard level rises.
- A safety integrity level tends to appear first in a customer’s specification or an export destination’s requirements, before it appears in regulation.
- The hard half is already done. A hazard list from an existing risk assessment — two axes in the hazardous zone at once, a transfer moving while the door is open — converts directly into the question “is this state reachable?”
Human-readable version: Why safety standards ask for formal methods
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