Final answer:
Radar services are limited to visual line of sight operations when radar mapping is unavailable to ensure the safety and accuracy of object detection, including those by 500-MHz frequency radar systems.
Step-by-step explanation:
When radar mapping is not available, radar services are typically limited to visual line of sight operations. This limitation is necessary due to the inability of radar systems to detect objects beyond the visual range when detailed mapping or high-precision radar is unavailable. Radar systems, including those that operate on 500-MHz frequencies, are used to detect the size and shape of objects such as aircraft and geological terrain. However, without radar mapping, they must rely on direct visual confirmation to ensure safety and accuracy of object detection.