If TDZ RVR is unavailable, what can be substituted?

• A. TDZ RVR
• B. METAR
• C. VISIBILITY
• D. Mid RVR

Answer: (D)

When using RVR-based minima, the most relevant visibility data for landing is the TDZ RVR. If that value isn’t available, you substitute with the Mid RVR from the same runway, provided it is reported. This keeps the minimums grounded in a runway-focused measure of visibility, since the Mid RVR is the next closest indicator along the approach path and still reflects conditions affecting landing. METAR visibility isn’t a suitable substitute for RVR because it’s a different type of measurement and may not accurately represent what the pilots will actually experience along the runway. TDZ RVR isn’t replaced by itself, and other substitutes exist only if Mid isn’t available, but for this scenario the Mid RVR is the correct alternative.