NASA Procedures and Guidelines: NPG 8621 Draft 1 Root cause: Along a chain of events leading to a mishap, the first causal action or failure to act that could have been controlled systematically either by policy/practice/procedure or individual adherence to policylpractice/procedure Contributing Cause A factor, event, or circumstance that led directly or indirectly to the dominant root cause or which contributed to the severity of the mishap Hierarchical Models LEVEL 3 SYSTEMIC FACTORS LEVEL 2 CONDITIONS EVENTS OR ACCIDENT MECHANISMc ������������������ �������������������������� NASA Procedures and Guidelines: NPG 8621 Draft 1 Root Cause: "Along a chain of events leading to a mishap, the first causal action or failure to act that could have been controlled systematically either by policy/practice/procedure or individual adherence to policy/practice/procedure." Contributing Cause: "A factor, event, or circumstance that led directly or indirectly to the dominant root cause, or which contributed to the severity of the mishap." c ������������������ �������������������������� Hierarchical Models EVENTS OR ACCIDENT MECHANISM LEVEL 2 CONDITIONS LEVEL 3 SYSTEMIC FACTORS