Which set of lights comprises the three systems referenced by the intensity steps chart?

• A. HIRL, RCLL, TDZL
• B. MIRL, RCLL, ALS
• C. HIRL, MIRL, TDZL
• D. TDZL, MIRL, ALS

Answer: (A)

The intensity steps chart focuses on the three runway lighting systems whose brightness levels you adjust together during operations: High-Intensity Runway Lights on the runway edges provide the brightest outlining, Runway Centerline Lighting System guides you along the centerline in low visibility, and Touchdown Zone Lights illuminate the area right after the threshold. These three systems share the same set of intensity steps, so they’re grouped together in the chart. Other lighting systems, like Approach Lighting or different edge-light intensities (MIRL), aren’t part of this particular trio, which is why the combination of HIRL, RCLL, and TDZL is the best fit.