FMEA

Fault Mode Effects Analysis (FMEA):

This methodology is used frequently by engineers to dissect physical systems and contemplate a variety of scenarios whereby things can go wrong. FMEA was first used in reliability, accident or failure analysis and vulnerability assessments. FMEA has found new life in aiding scientists, operators and policy makers to improve their understanding , awareness of uncertainty and risk-based decision-making processes. It is highly adaptable to the use of subject matter experts and terrorist scenarios where the event must be declared without resort to the requirement to determine the likelihood of such a scenario. This drives the design process to meet appropriate thresholds determined by the scenarios themselves.

FMEA analyzes how serious or dangerous is the effect that can be caused by a specific component or subsystem that goes wrong. FMEA works well with cascading failures and causality. Causality can be introduced in an FMEA construct by starting with a prevailing or design envelope determined, general hazardous environment that provides the catalyst for events or incidents to occur with often serious consequences. FMEA usually bypasses the question - How likely is it expected to happen? This is convenient for analysis of highly unlikely scenarios that, should they occur, result in horrendous consequences.

FMEA can be used in either quantitative or a qualitative assessments. Once the FMEA is constructed in a tabular form, the risk manager seeks appropriate points of interdiction that promise to disrupt cascading failures and break causal chains before they can become catastrophic. FMEA accommodates such interdiction through an extra column in the table that reduces the vulnerability and degree of damage caused when countermeasures or mitigation initiatives impact the dynamics and results of the chosen scenario.

FMEA failure scenarios can be prioritized based on the question - How likely is such a scenario to occur. However, such a proposition should never eliminate the low incident, high consequence scenarios from consideration.