eyeson Abstraction from Physical design Software engineers are doing system design Autopilot Syster oftware Design of Expert Requirements Engineer Autopilot Most errors in operational software related to requirements Completeness a particular problem Software"failure modes"are different Usually does exactly what you tell it to do Problems occur from operation, not lack of operation Usually doing exactly what software engineers wanted Computers and Risk Typical Fault Trees Hazard Software (error) Hazard Cause Probability Mitigation Software error Test softwarec ￾✂✁✂✄☎✁✂✆☎✝✂✞✠✟✌☞✂☞ ✙✝✂✖✠✚✂✛✂✜✁✂✒✆✣✢✂✞✂✤✠✥✧✦✆☎★ Abstraction from Physical Design Software engineers are doing system design Expert Autopilot Autopilot Engineer System Software Design of Requirements Most errors in operational software related to requirements Completeness a particular problem Software "failure modes" are different Usually does exactly what you tell it to do Problems occur from operation, not lack of operation Usually doing exactly what software engineers wanted c ￾✂✁✂✄☎✁✂✆☎✝✂✞✠✟✌☞✱✡ ✙✝✂✖✠✚✂✛✂✜✁✂✒✆✣✢✂✞✂✤✠✥✧✦✆☎★ Typical Fault Trees ... ... 0 Test software Hazard Cause Probability Mitigation Software Error (error) fails Software Hazard OR