What do alternating red and green lights signify in runway environments?

• A. Runway centerline lights
• B. Approach end warning signals
• C. Marking runway hazard areas
• D. Indicating aircraft taxi routes

Answer: (C)

Alternating red and green lights in runway environments are used to signify marking runway hazard areas. These lights serve a critical safety function by alerting pilots to the proximity of areas that may pose risks during landing and takeoff. For example, they could indicate the boundaries of obstacles, such as construction zones or other hazards on or near the runway.

The use of alternating colors helps to catch the attention of pilots, distinguishing these hazard areas from regular runway markings or lighting. They indicate to pilots that they should exercise caution due to potential dangers in that vicinity.

In the context of the other choices, runway centerline lights typically only display white lights or a combination of white lights along the runway for guidance. Approach end warning signals are often a single color, such as red, to indicate an immediate warning. Meanwhile, indicating aircraft taxi routes usually employs solid lights or specific colors like blue to mark taxi pathways, rather than the alternating red and green scheme. Thus, the identification of hazard areas through alternating red and green lights is the correct function in this scenario.