3.3_SMSM_201509 Originally published September 2015 Uncontrolled copy when downloaded 29 The Safety Analysis and Risk Mitigation Process  Section 3  Section 8 identifies sources of data to use in the SRM analysis.  Once the system elements are listed, a careful review of the NAS change description should be  conducted. A bounded system limits the analysis to the components necessary to adequately  assess the safety risk associated with the NAS change, system, and/or operation. When there  is doubt about whether to include a specific element in the analysis, it is preferable to include  that item, even though it might prove irrelevant during the hazard identification phase.  The 5M Model can be used to capture the information needed to describe the system and aid in  hazard identification. The 5M Model uses a Venn diagram to depict the interrelationships  among its five elements, as seen in Figure 3.5. To adequately bound and describe a system, it  is important to understand the relationships between the elements of the 5M Model.  The 5M Model illustrates five integrated elements that are present in any system:  3.3.3.2 5M Model Method  • Media:  The environment in which the system is operated and maintained • Management:  The procedures and policies that govern the system’s behavior • Machine:  The equipment used in the system, including hardware, firmware, software, human-to-system interfaces, system-to-system interfaces, and avionics • (hu)Man/Person:  The human operators, maintainers, and affected stakeholders • Mission:  The clearly defined and detailed purpose of the NAS change proposal or system/operation being assessed The 5M Model and similar techniques are used to deconstruct the proposed NAS change in  order to distinguish elements that are part of or affected by the proposed NAS change. These  elements later help to identify sources, causes, hazards, and current and proposed risk  mitigation strategies.  Figure 3.5: 5M Model 