## 3.5 DIAAT Phase 3: Analyze Risk 

## A 

## 3.5.1 Overview 

An accident or incident rarely results from a single failure or event. Consequently, risk analysis is seldom a binary (e.g., on/off, open/closed, broken/operational) process. Risk and hazard analyses can identify failures from primary, secondary, or even tertiary events. 

During the risk analysis phase: 

## ANALYZE RISK 

 Identify controls  Determine the severity and likelihood of the hazard’s effect 

• Evaluate each hazard (identified during the “Identify Hazards” phase) and the system state (from the “Describe the System” and “Identify Hazards” phases) to determine the controls, 

• Analyze how the operation would function should the hazard occur, and 

• Determine the hazard’s associated severity and likelihood and provide supporting rationale. 

## 3.5.2 Controls 

A control  is anything that currently reduces a hazard’s causes or effects. Policies, procedures, hardware, software, or other tools can only be considered controls if they are part of the operating National Airspace System (NAS) and have demonstrated effectiveness. Understanding controls affects the ability to determine credible effects. Certain controls, such as the Traffic Collision Avoidance System, may only be in place in certain operating environments or under certain system states. Do not document safety requirements as controls; safety requirements are only planned or proposed ways to reduce risk. Refer to Section 3.7.3 for information about documenting safety requirements. 

Provide supporting data and/or a rationale that confirms the control’s use, applicability, and availability related to the hazard. For instance, if orders are identified as controls, cite the specific version, paragraph, and/or section number(s). Alternatively, if equipment is identified as a control, discuss how it reduces or manages the risk. Only document the controls associated with the NAS change under evaluation. When considering existing hazards identified through safety audits or post-event risk analyses, consider any control(s) that either minimized the hazard’s effect or failed. 

Table 3.2 provides broad examples of controls. This is not a comprehensive list of controls; each identified control should be directly applicable to the hazard being addressed. 

