What are Runway Threshold and End Lights used for?

The correct answer highlights how runway threshold and end lights play a crucial role in aviation by marking the limits of the usable runway. These lights serve as visual guidance for pilots during approach and landing, especially in low-visibility conditions.

Runway threshold lights are particularly important because they define the actual starting point of the runway that is available for landing and takeoff, ensuring pilots can accurately judge their altitude and position relative to the runway. Similarly, runway end lights indicate the conclusion of the runway, helping pilots understand where the runway finishes and aiding in preventing runway overruns.

Being aware of the presence of approach lighting systems is vital as these systems provide guidance to pilots as they approach for landing, enhancing safety during this critical phase of flight. While the other choices reference various aspects of aviation lighting, the correct option specifically addresses the function of these lights in relation to approaching and landing, making it the most relevant answer.