iii  3.5.2 Controls  3.5.3 Defining a Credible Hazard Effect  3.5.4 Defining Risk  3.5.4.1  How to Define and Determine Risk  3.5.4.2  Determining Severity  3.5.4.2.1 Assessing Severity of NAS Equipment Hazard  Effects  3.5.4.2.2 Using the NAS Equipment Worst Credible Severity  Table  3.5.4.3  Determining Likelihood  3.5.4.3.1 Likelihood versus Frequency  3.5.4.3.2 What to Consider When Defining Likelihood  3.5.4.3.3 Calculating Likelihood with Quantitative Data  3.5.4.3.4 Determining Likelihood When No Data Are  Available  3.6 DIAAT Phase 4: Assess Risk  3.6.1 Overview  3.6.2 Risk Levels and Definitions  3.6.2.1  High Risk  3.6.2.2  Medium Risk  3.6.2.3  Low Risk  3.6.3 Plotting Risk for Each Hazard  3.7 DIAAT Phase 5: Treat Risk  3.7.1 Overview  3.7.2 Risk Management Strategies  3.7.2.1  Risk Control  3.7.2.2  Risk Avoidance  3.7.2.3  Risk Transfer  3.7.2.4  Risk Assumption  3.7.3 Documenting Safety Requirements  3.7.4 Determining Predicted Residual Risk  4. Developing Safety Performance Targets and Monitoring Plans 4.1 Developing Safety Performance Targets 4.2 Developing the Monitoring Plan 4.2.1 Monitoring Activities  4.2.2 Frequency and Duration Monitoring  4.3 Post-SRM Monitoring  4.3.1 Monitoring and Current Risk  4.3.2 Predicted Residual Risk Is Not Met  4.3.3 Predicted Residual Risk Is Met  4.3.4 Residual Risk  4.3.5 Monitoring and Tracking of Changes Added to the Operating NAS 