Which of the following are primary elements of unmanned aircraft systems?

The primary elements of unmanned aircraft systems (UAS) consist of three critical components: mechanical structure, electronic systems, and software program.

The mechanical structure refers to the physical frame and components of the UAS, which provide the necessary durability and support for flight. Electronic systems include the sensors, cameras, and communication devices essential for operation and control of the drone. The software program encompasses the algorithms and applications used for flight management, navigation, and data processing, making it a fundamental aspect of UAS functionality.

In contrast, the other choices involve elements that do not encapsulate the inherent characteristics of the unmanned aircraft systems themselves. Crew members, maintenance logs, and flight plans pertain to operational and organizational aspects rather than the components of the UAS. Similarly, weather reports, communication systems, and air traffic control resources are factors that affect flight but are not integral parts of the aircraft itself. Lastly, navigation aids, propulsion methods, and power sources might seem relevant to aircraft operation, but they are not as comprehensive or defining as the mechanical, electronic, and software elements that directly constitute the UAS.