This book reports on the design and development of a system that assists remote pilots during navigation. It focuses on the design and development of a ground station that assists remote pilots  during maneuvers such as take-off or landing procedures, in case a high accuracy is required or the GNSS signal is lost. Continuing the tradition of the previous volume, and being its revised edition, this book covers the latest UAS regulations together with updated strategies for finding the best and safest trajectory and landing site, with a special focus on urban air mobility applications. It describes the system's components, such as the LiDAR sensor, the temperature and humidity sensors, the Raspberry Pi 3 controller, and the Bluetooth Low Energy Transmitter, in detail. Further, it discusses the experimental tests carried out in both controlled laboratory settings and real-world environments. All in all, this book offers a timely survey of both regulations of and electronics design for unmanned aircraft systems, with extensive information on new methods and technologies for the development of Detect and Avoid systems for unmanned aerial vehicles.