What is the purpose of approach lights at an airport?

Approach lights at an airport serve an essential role in guiding pilots as they make their final approach to the runway. Their primary purpose is to assist in the alignment of the aircraft with the runway centerline. This ensures that as the aircraft descends towards landing, the pilots can clearly see where they need to be, helping them maintain the correct path for a safe touchdown.

The approach lighting system is designed to be visible from a distance and is configured in a way that provides visual cues about the alignment with the runway. This becomes particularly critical in low visibility conditions, such as fog or heavy rain, where precise visual guidance is needed.

While illuminating the runway at night is important for safety, that function is primarily served by runway lights, rather than approach lights. The other options related to ground visibility and signaling movement restrictions pertain to different systems entirely, such as taxiway lights and signage, which help with vehicle and aircraft movements on the ground. Therefore, understanding the specific function of each type of lighting is crucial for safe airport operations.