Sample 1

FAA - Safety Risk Matrix

This sample was extracted from the (since superseded) FAA Advisory Circular No. 120-92, Introduction of Safety Management Systems for Air Operators.

• Unacceptable (Red). Where combinations of severity and likelihood cause risk to fall into the red area, the risk would be assessed as unacceptable and further work would be required to design an intervention to eliminate that associated hazard or to control the factors that lead to higher risk likelihood or severity.
• Acceptable (Green). Where the assessed risk falls into the green area, it may be accepted without further action. The objective in risk management should always be to reduce risk to as low as practicable regardless of whether or not the assessment shows that it can be accepted as is. This is a fundamental principle of continuous improvement.
• Acceptable with Mitigation (Yellow). Where the risk assessment falls into the yellow area, the risk may be accepted under defined conditions of mitigation. An example of this situation would be an assessment of the impact of a non-operational aircraft component for inclusion on a MEL (MEL). Defining an Operational (“O”) or Maintenance (“M”) procedure in the MEL would constitute a mitigating action that could make an otherwise unacceptable risk acceptable, as long as the defined procedure was implemented. These situations may also require continued special emphasis in the safety assurance function.

Sample 2

EUROCONTROL - Risk Assessment and Mitigation in ATM

The table below has been extracted from EUROCONTROL ESARR4 - Risk Assessment and Mitigation in ATM. It associates the severity class (determined using a severity classification scheme) with a tolerable probability (i.e., a maximum tolerable probability of ATM directly contributing to safety occurrences) to show that the more severe the effect of the hazard the less desirable it is that the hazard occurs.

Note: The risk classification scheme only refers to an overall safety performance of ATM at ECAC and national level and is not directly applicable to the classification of individual hazards. To achieve this, a method of apportionment of the overall probability to the constituent parts of the ATM system may need to be developed. This apportionment may be done per phase of flight and/or, per accident types.

Severity classes are defined as follows:

1. [most severe] - accidents
2. - serious incidents
3. - major incidents
4. - significant incidents
5. - no safety effect

Quantitative expressions for severity classes 2,3,4,5 are yet to be determined.

Go back to Risk Assessment article or Safety Management category.