ALE, FMEA, FMECA, qualitative methods: is it really what we need!?

ALE, FMEA, FMECA, qualitative methods: is it really what we need!?

Mar 17th, 2011

ALE, FMEA, FMECA, qualitative methods: is it really what we need!? discusses the evaluation of systems’ failure. An array of methodologies exist. Among these the are Failure Mode and Effects Analysis (FMEA) and the Failure Mode and Effects Criticality Analysis (FMECA).

Many Risk Assessment use Annual Loss Expected (ALE) as a metric for impact or consequences.

ALE, FMEA, FMECA, qualitative methods: is it really what we need!?

FMEA/PIG risk matrix 4×4. Are the “not likely”/”most unlikely” events with extreme consequences IDENTICAL to an “expected”/”will occur” event with negligible consequences risk?

Impact analysis of every potential defect on functionality

The essence of FMEA/FMECA is the impact analysis of every potential defect on functionality of the whole system. Moreover FMEA/FMECA also help defining the order of potential defects according to the level of their severity.

In fact, this has lead in the past to some “aberrant” studies. Indeed hundreds, if not thousands of defect scenarios and resulting paths to failure were analyzed in huge “trees”. These were disproportionate with the available data and their quality, leading to misleading perception of the accuracy of the answers.

Instead, the ultimate goal of any Risk exercise should be to define optimal proportion between threats and costs of system’s protections. Available data and their uncertainties should inform that optimum. The system can be anything, an IT system including hardware and software, a transportation system, a static infrastructure, an operation, such as a mine, a commercial wharf, a humanitarian program, a rescue or military operation, etc..

Once we develop a proper approach, we can plan appropriate preparedness actions. Therefore time needed for appropriate reactions in case of a hazard occurrence, i.e. the source of the risk, is decidedly shortened. The lack of appropriate preparation may lead the system and its owner, to collapse. Ultimately it does not matter whether it is a corporation, a governmental entity, an NGO.

Road towards long-term survivability

Appropriate reactions based on a clear plan pave the road towards long-term survivability and development of the system and its owner. Actually we have pointed out and discussed this point in detail in our book Improving Sustainability through Reasonable Risk and Crisis Management.

Specific literature very often skips the issue of quantitative methods of risk assessment. Furthermore it only focuses on “mainstream” and often very poorly implemented qualitative methods or misleading ALE/ FMEA/ FMECA.

The root causes of this lack of attention to quantitative methods are nested in poor information, misunderstanding about the data required to perform a quantitative approach and “syndromes” on which we have already expanded in past postings on 16 common human traits.

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Category: Consequences, Hazard, Mitigations, Probabilities, Risk analysis, Risk management, Tolerance/Acceptability

One response to “ALE, FMEA, FMECA, qualitative methods: is it really what we need!?”

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