Summary of Levels and Approaches

Surety by Everything Working Sufficiently as Intended

I:1. Foresight and good practices

I:2. Mitigation after the fact and correcting what went wrong

Surety by Proactive Human Intervention

II:3. Proper operations with thorough understanding, independent assessment,

and continuous improvement

II:4. Administrative control reduces the probability of occurrence

Surety by Positive Measures from Science and Engineering

III:4.5 Engineered controls reduce the probability of occurrence

III:5. Predictable parallel positive measures--all must succeed

III:6. Predictable independent serial positive measures--one must succeed

III:7. Predictable cumulative/comparative/adaptive positive measures

Surety from Laws on Nature and Mathematics

IV:8. Undesirable consequences are physically impossible.

Previous slide

Back to first slide

View graphic version

Questions and Comments || Acknowledgment and Disclaimer