Which item is NOT part of the listed items used for instrument approach lighting and runway references?

• A. Runway end identifier lights
• B. Threshold lights
• C. PAPI lights
• D. Touchdown zone markings

Answer: (C)

Understanding what belongs to instrument approach lighting and runway references helps you see how pilots navigate and land. The items in that group are lights and markings that guide you to the runway and indicate where to touch down: runway end identifier lights flash at the threshold to identify the runway end, threshold lights mark the start of usable runway, and touchdown zone markings provide distance cues for where landing should occur. PAPI lights, however, belong to a separate system—visual glidepath indicators—that show whether you’re on the correct descent angle by color changes. They provide vertical guidance but aren’t part of the approach lighting system or the standard runway reference markings, which is why they’re not included in that list.