What do TouchDown Zone Lights (TDZL) consist of?

TouchDown Zone Lights (TDZL) are specifically designed to assist pilots in identifying the touchdown zone on the runway during landing, particularly in low-visibility conditions. The correct answer involves two rows of transverse light bars positioned around the runway centerline.

These light bars are typically arranged in a way that they provide visual guidance by illuminating the area where aircraft are expected to touch down. This configuration helps enhance situational awareness for pilots as it clearly marks the touchdown area, ensuring they can accurately line up for a safe landing.

The other options do not accurately describe TouchDown Zone Lights. For instance, horizontal light strips along the centerline may be a feature of different lighting systems but do not represent the TDZL specifically. Single lights marking the threshold could refer to threshold lights but do not encompass the features of TDZL. Colored lights indicating terrain are unrelated to TDZL and serve different purposes, such as warning pilots about terrain height and proximity. Thus, the described two rows of transverse light bars accurately reflect the function and design of TDZL.