coordinate with the ATO Chief Safety Engineer to address the risk and any potential corrective actions. 

Refer to Section 3.7.2 for risk management strategies. Refer to Section 5.5.3 for information on the administrative process of addressing existing high-risk hazards and obtaining approval for their risk reduction. 

## 3.4.3 Elements of Hazard Identification 

When considering new NAS equipment and procedures or planned modifications to current NAS equipment and procedures, define the data sources and measures necessary to identify hazards. The elements of a thorough system description contain the potential sources of hazards associated with the proposed NAS change. There are numerous ways to do this, but all require at least three elements: 

• Operational expertise that relates specifically to the operation or equipment, 

• A defined hazard analysis tool. 

## 3.4.3.1 Techniques for Hazard Identification and Analysis 

In many cases, to identify and analyze safety hazards, a Preliminary Hazard List (PHL) and the required Hazard Analysis Worksheet (HAW) will suffice. Some cases, however, may require other tools or techniques (refer to Section 3.4.3.1.3). 

## 3.4.3.1.1 Developing a PHL 

The process of describing the system using a tool like the 5M Model is designed to facilitate brainstorming for sources of hazards. The next step in the hazard identification process is to develop a PHL. The PHL  may be a combination of hazards, causes, effects, and system states. The items listed in the PHL all have the potential to be placed into the HAW. It is at the panel’s discretion to decide which items belong in the HAW during the Identify Hazards and Analyze Risk phases of the SRM process. For more guidance on which items should be placed into the HAW, refer to Section 3.5. 

## 3.4.3.1.2 Developing a HAW 

When hazards are identified, the HAW , a worksheet used to document a safety analysis, is required as part of the ATO SRM process. It is also used both for Operations and Second-Level Engineering. When developing the HAW, it is crucial to consider the hazards inherent to all aspects of an operation without regard to risk. ATO safety professionals use the HAW in nearly all risk management applications, except in the most time-critical situations. 

Training or experience in various hazard analysis techniques, and 

Using the HAW helps panels overcome the tendency to focus on safety risk in one aspect of an operation and overlook more serious issues elsewhere in the operation. Its broad scope guides the identification of issues that may require analysis with more detailed hazard identification tools. Refer to Section 5.4.1 and Section 5.4.4.6 for a description of the expected contents of the HAW. 

## 3.4.3.1.3 Other Accepted Tools and Techniques 

If the safety analysis calls for an additional means to identify hazards and compare solutions, select the methodology that is most appropriate for the type of system being evaluated. The Service Center and/or an AJI safety case lead can provide additional guidance on which tool(s) to use for various types of NAS changes (refer to Table 3.1). 

