If TDZ RVR is below 1600, how many operative RVR systems are required?

• A. Two operative RVR systems are required, and all RVR are controlling except a fourth far-end RVR
• B. Only one RVR system is required
• C. No RVR systems are required below 1600
• D. All RVR must be replaced with MID

Answer: (A)

When the touchdown-zone RVR falls below 1,600 feet, you need redundancy in visibility data for the approach or landing. Specifically, two RVR systems must be operative to provide multiple, independent measurements you can rely on during low-visibility operations. In addition, all RVR readings on the runway are available for consideration, but the far-end (fourth) RVR reading does not count as controlling data. This setup ensures there’s enough reliable information to judge visibility while avoiding over-reliance on a single distant sensor that could be misleading in tight, low-visibility conditions.