Safety Risk Assessment – 673.25(c)
As part of the new SRM process, PBT has developed methods to assess the likelihood and severity of the consequences of identified hazards, and prioritizes the hazards based on the safety risk. The process continues the use of the Risk Register described in the previous section to address the next two components.
To accurately assess a risk, PBT may need to perform an investigation. PBT currently investigates accidents or crashes, but will need to develop a full investigation procedure to inform the SRM process. The investigation procedure will start with the Assessment Form and framework found in the [name of agency procedure] and will be developed to cover all risk assessments. Once fully developed, the document will become the Investigation SOP. The SOP will include accident investigation procedures as well as risk investigation procedures. These procedures will be used to investigate risks identified from multiple sources, including the ESRP.
Safety risk is based on an assessment of the likelihood of a potential consequence and the potential severity of the consequences in terms of resulting harm or damage. The risk assessment also considers any previous mitigation efforts and the effectiveness of those efforts. The results of the assessment are used to populate the third and fourth components of the Risk Register as presented in Figure 5.
Figure 5: Safety Risk Assessment Steps in Populating the Risk Register
Hazard
Type
Likelihood
Consequences
Resolution
The risk assessment is conducted by the CSO and their safety team supplemented by subject matter experts from the respective department or section to which the risk applies. The process employs a safety risk matrix, similar to the one presented in Figure 6, that allows the safety team to visualize the assessed likelihood and severity, and to help decision-makers understand when actions are necessary to reduce or mitigate safety risk.
Figure 6: Safety Risk Assessment Matrix
Risk Assessment Matrix
Severity - Likelihood
Frequent (A)
Catastrophic (1) - High
Critical (2) - High
Marginal (3) - High
Negligible (4) - Medium
Probable (B)
Catastrophic (1) - High
Critical (2) - High
Marginal (3) - Medium
Negligible (4) - Medium
Occasional (C)
Catastrophic (1) - High
Critical (2) - Medium
Marginal (3) - Medium
Negligible (4) - Low
Remote (D)
Catastrophic (1) - Medium
Critical (2) - Medium
Marginal (3) - Low
Negligible (4) - Low
Improbable (E)
Catastrophic (1) - Medium
Critical (2) - Low
Marginal (3) - Low
Negligible (4) - Low
Although the current version of the matrix relies heavily on the examples and samples that are listed on the PTASP Technical Assistance Center website, lessons learned from the implementation process during the coming years will be used to customize the matrix that PBT will use to address our unique operating realities and leadership guidance.
The Risk Assessment Matrix is an important tool. If a risk is assessed and falls within one of the red zones, the risk is determined to be unacceptable under existing circumstances. This determination means that management must take action to mitigate the situation. This is the point in the process when SRMs are developed. If the risk is assessed and falls within one of the yellow zones, the risk is determined to be acceptable, but monitoring is necessary. If the risk falls within one of the green zones, the risk is acceptable under the existing circumstances.
Once a hazard's likelihood and severity have been assessed, the CSO enters the hazard assessment into the Risk Register, which is used to document the individual hazard and the type of risk it represents. This information is used to move to the next step, which is hazard mitigation.
