## 4 Core Insights and Critical Reflections
### Constraints of Policies, Regulations, and Standardization Systems  
The rapid development of UAV-RS has also introduced a range of challenges related to policies, regulations, and standardization systems (Table 11). These constraints not only affect the lawful and compliant operation of UAV-RS, but also hinder its application expansion and industrialization in specific fields. Key issues include airspace management, data security and privacy protection, and the absence of unified industry standards. (1) Airspace management and flight approval are among the primary bottlenecks constraining the development of the low-altitude economy. Airspace is a limited resource, and how to plan and manage low-altitude airspace effectively to ensure the safe operation of UAVs alongside other aircraft remains a major challenge for governments and aviation authorities worldwide. Currently, many countries and regions impose strict regulations on UAV flight activities, such as designating no-fly zones, restricting flight altitude and range, and requiring pre-flight plan approvals [47]. While these measures aim to ensure aviation safety and national air defense, they also pose significant obstacles to UAV-based remote sensing operations. For example, it is often difficult to obtain flight approvals for large-scale UAV-RS missions, limiting their practical application. In the United States, the Federal Aviation Administration (FAA) requires UAVs to operate within the visual line of sight (VLOS) of the operator, mandates registration for commercial drones, and enforces compliance with Part 107 regulations, which stipulate that operations must be conducted by certified remote pilots [217]. In China, the use of low-altitude airspace is strictly regulated,and the proportion of accessible airspace for light and small UAVs (typically below 120 m) that does not require approval is relatively low. The lack of a flexible airspace access mechanism makes it difficult for UAVs to operate in densely populated areas or near critical infrastructure, thus limiting their applications in key domains such as urban management and emergency response. (2) Data security and privacy protection have become growing concerns for both the public and regulatory authorities. Sensors mounted on UAVs--particularly high-resolution cameras--are capable of capturing vast amounts of imagery that may contain personal information, corporate data, or sensitive facility details. If mishandled or misused, such data could pose serious risks of data breaches and privacy violations [218]. For example, UAVs operating over urban areas may inadvertently capture private activities of residents or confidential business operations. How to regulate the collection, storage, transmission, use, and disposal of UAV-acquired data--while safeguarding personal privacy and commercial confidentiality--has become an urgent legal and ethical challenge. At present, the legal and regulatory frameworks concerning UAV data security and privacy protection remain underdeveloped, with a lack of clear operational guidelines and defined responsibilities. There is an urgent need to formulate dedicated management regulations for UAV-RS data, clarifying data ownership, usage rights, and privacy protection requirements, while also strengthening oversight and enforcement mechanisms. (3) The lack of industry standards and specifications is another major bottleneck hindering the standardized development and widespread application of UAV-RS. As an