Under what conditions can a pilot descend below MDA or DA?

The correct answer emphasizes the importance of having visual references for the runway before descending below the Minimum Descent Altitude (MDA) or Decision Altitude (DA). In aviation, these altitudes are critical safety guidelines designed to ensure a pilot maintains a safe position relative to the terrain and obstacles during an approach.

When the runway and other visual references are distinctly visible, it indicates that the pilot can safely continue the approach to landing. This can include seeing the runway environment, such as runway markings, lighting, or the actual runway itself. The presence of these visual cues allows the pilot to assess their position relative to the ground and make informed decisions about the landing, thus aligning with regulatory standards for safe flight operations.

The other choices do not capture the essential condition needed for a safe descent below MDA or DA. Simply having visibility greater than 1 mile does not guarantee the necessary visual references for a safe approach. Flying level at MDA without visual confirmation could lead to dangerous situations since the pilot may not be aware of obstacles or the runway's actual position. Finally, relying solely on the pilot's perception of safety without visual references conflicts with established safety protocols, which are designed to minimize risks during the critical phases of landing.