This is an 5 by 5 matrix used for assessing the level of risk associated with a hazard. This example is based on an Aviation safety risk matrix published by the International Civil Aviation Authority (ICAO) in their Safety Management Manual. stakeholdermap.comSimilar matrices are used to manage health and safety risks in multiple industries, where if the risk were realised i.e. if the risk happened, it could result in injury to human or animal resources.
Severity definitionsThis matrix rates the severity of the risk on a scale from negligible to catatrosphic. Each severity rating has a clear definition:
|Catastropic||If the risk occured it would:
|Hazardous||If the risk occured it would cause:
If the risk occured it would cause:
If the risk occured it would cause a:
Risk probability tableThe x axis categorises the probability of a risk occuring. Each rating is numbered, which combined with the risk severity gives the risk index (more on this later).
|Frequent||Likely to occur many times (has occurred frequently)||5|
|Occasional||Likely to occur sometimes (has occurred infrequently)||4|
|Remote||Unlikely to occur, but possible (has occurred rarely)||3|
|Improbable||Very unlikely to occur (not known to have occurred)||2|
|Extremely improbable||Almost inconceivable that the event will occur||1|
Risk tolerability or traffic lightsThe ICAO group risks into three zones: acceptable, tolerable and intolerable. These zones or regions are shown on the matrix using a traffic light system of red, amber and green.
Once a risk is assessed the combination of the probability and severity gives a risk index. For example a risk with a probability level of 4 and a severity of B has an index of 4B which means that action must be taken to reduce the probability and/or severity so that the risk falls within tolerable levels.
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Risk Matrix References
ICAO in its Safety Management Manual. https://www.icao.int/safety/SafetyManagement/Documents/Doc.9859.3rd%20Edition.alltext.en.pdf, Pg 2 – 28 – 2 - 29