What minimum visibility is required in RVR when the ILS RWY 25L is inoperative?

The minimum visibility required in RVR (Runway Visual Range) when the ILS (Instrument Landing System) runway is inoperative is typically established to ensure safe landing conditions. When ILS is not available, pilots rely more on visual references, making visibility a critical factor for safe operations.

The correct answer of 3000 feet indicates the established standard minimum visibility for operations when the ILS is down. This standard is in place to help maintain safety during approaches and landings, allowing pilots sufficient visual cues to identify the runway environment and ensure a safe landing.

In the context of an ILS approach, when it's inoperative, a higher visibility threshold would be necessary to compensate for the lack of precision guidance typically provided by the ILS system. Thus, while options like 4000 feet, 4500 feet, and 5000 feet may represent safer minimums under different conditions or for other types of approaches, they are not the baseline requirement in this specific scenario where the ILS is not operational. Therefore, 3000 feet stands as the correct minimum visibility for RVR when ILS RWY 25L is inoperative.