## 4 Discussion  
In this study, the STAMP/STPA methodology was applied to address the problems arising from rapid urbanization by integrating UAS into public safety systems. This research aimed to achieve the following objectives:  
1. To identify and analyze the potential hazards and challenges associated with integrating UAS into public safety/law enforcement systems in urban environments. 2. To develop a comprehensive set of safety requirements and guidelines for the safe and effective deployment of UAS in public safety missions. 3. To propose strategies for efficient infrastructure investment and resource allocation based on STAMP/STPA results. As most existing UAS applications in public safety do not involve specific systems but rather direct control for mission execution, a case study was conducted based on considerations necessary for public safety missions derived from a literature review and case studies. As a result, 99 loss scenarios, 99 safety constraints, and 297 recommendations were identified. These findings align with previous research indicating that the STAMP/STPA method is suitable for identifying hazards at the initial concept stage and thus fulfills research objective 1 [35; 36; 37; 38]. Moreover, the analysis process and proposed framework provided safety constraints and recommendations, which satisfy research objective 2. Regarding UAS integration, while UTM and U-space envision a comprehensive ecosystem of technologies, services, procedures, and regulations for safe and efficient UAS operations in low-altitude urban airspace, these frameworks do not sufficiently consider the specificities of public safety applications, emphasizing the need for research such as this [21; 22]. Since rapid urbanization primarily affects developing countries, cost-effective approaches are needed to address this issue. Therefore, this study applied a simple risk matrix within the proposed framework to prioritize cost investments. Although the method was relatively simple, it demonstrated potential scalability. The framework aimed to prevent duplicate spending during budgeting, development, and operation by involving stakeholders in the analysis process and identifying their roles and contributions. However, these attempts revealed various limitations and areas for improvement concerning research objective 3. STPA proved to be a highly effective method for risk analysis. However, the risk matrix approach had limitations in addressing stakeholder roles and cost-efficiency, merely providing prioritization. To overcome this, considering the actual costs of implementing the proposed safety constraints and recommendations, along with Cost-Benefit Analysis (CBA) and Cost-Utility Analysis (CUA), would be necessary to assess the utility of alternatives [48]. Meanwhile, the analysis of AAIB and ASRS reports revealed that the content and format of the reports vary depending on each country's regulations. In addition, as shown in Figure 8, the statistics on the causes of accidents/incidents differed significantly between the two organizations, which is likely due to the differences in regulations of each country. The purpose of AAIB is to formally investigate and report on actual accidents and serious incidents, potentially identifying more non-human factors. In contrast, ASRS is a voluntary and confidential system for pilots, controllers, and maintenance personnel to report safety issues. These differences highlight the need for consistent guidelines for UAS integration, making the stakeholder-inclusive analysis in this study meaningful. In this study and the statistics from the ASRS, human factor-related risks and incidents/accidents are prominent, but this could potentially be addressed as the level of autonomy increases. This can also be seen in the ASRS yearly accident statistics in Table 7.  
This statistic is the result of aggregating keyword frequency by year.