Which of the following lighting systems is required for CAT II operations?

For CAT II operations, the requirement for ALSF-1 or ALSF-2 approach lights is critical due to their role in providing pilots with visual references during low visibility conditions. These approach lighting systems enhance the pilot's ability to transition from instrument flight to visual flight, which is essential for a safe landing when the visibility is limited.

ALSF-1 (Approach Light System with Sequence Flashing Lights) and ALSF-2 are specifically designed to help during approach phases with visibility less than 1 mile, allowing precision when aligning with the runway. They consist of a series of lights in a specific pattern that guide pilots toward the runway and indicate critical decision points during the descent.

In this context, other lighting systems, while important for airport operations, do not fulfill the specific visual guidance needs required for CAT II approaches. For instance, runway edge lights provide visual delineation of the runway but do not offer substantial assistance in low visibility during the approach phase like ALSF systems do. Similarly, basic taxiway lights and obstruction lighting serve their purposes in taxiway safe navigation and marking hazards, respectively, but do not directly support approach operations in the same way ALSF does.