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)
Example:
- 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 |
Note
Each Impact Level is derived from the result from the First/Second Parties column AND/OR the Third Parties column.
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