A way to structure risk descriptions is the ECE Risk Expression, which gives a simple, clear description and assists risk assessment by identifying the adverse Event, likely Cause and the expected Effect. It is structured as follows:
E – what is the adverse EVENT?
C – what is the likely CAUSE? (hazards)
E – what is the expected EFFECT? (outcomes / consequences)
- Event: aircraft control restriction
- Likely Cause: loose tools in the cockpit
- Effect: loss of control in flight
- Risk description: loose tools left in the cockpit cause control restriction which leads to loss of control in flight
|LIKELIHOOD: how often the Cause could potentially lead to the stated Event and result in the stated harmful Effect|
|Likelihood level||Frequency descriptor: use available evidence and appropriate judgment to estimate the potential likelihood level|
|5 – Almost certain||The Safety Risk (stated CEE) could occur at least once a month|
|4 – Likely||The Safety Risk could occur at least once a year|
|3 – Possible||The Safety Risk could occur once in 2 years|
|2 – Unlikely||The Safety Risk could occur once in 3 years|
|1 – Rare||The Safety Risk could occur once in 4+ years|
|IMPACT: estimation of potential harm, to how many people as a result of the stated effect|
|Impact level||Descriptor: use available evidence and appropriate judgment to estimate the potential harm below|
|First and second parties||Third parties|
|5 – Very High||Such as following the loss of passenger carrying aircraft (est. 50+ fatalities)||10+ fatalities|
|4 – High||Such as following the loss of passenger carrying aircraft (est. 20-49 fatalities)||3-9 fatalities|
|3 – Medium||Such as following the loss of smaller passenger carrying aircraft (est. 10-19 fatalities)||1-2 fatalities|
|2 – Low||Such as following the loss of smaller passenger carrying aircraft (est. 6-9 fatalities)||Any serious injuries|
|1 – Very Low||Such as following the loss of a small GA aircraft (est. 0-5 fatalities and/or any number of injuries)||Any non-serious injuries|
Each Impact Level is derived from the result from the First/Second Parties column AND/OR the Third Parties column.
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