What must a pilot have to continue the approach inside the FAF if visibility falls below prescribed limits?

To continue the approach inside the Final Approach Fix (FAF) when visibility decreases below the minimum prescribed limits, a pilot must have visual reference to the runway environment. This is critical for ensuring a safe landing, and the flight visibility from the flight deck is a key factor in this assessment.

When a pilot determines that they can maintain visual references necessary for landing, they can continue the approach, even if the reported visibility is below the minimums—provided crew judgment and experience support that decision. This underscores the importance of situational awareness and the pilot's ability to evaluate conditions from their unique perspective in the cockpit.

The other options, while important in various contexts, do not directly address the requirement for visual reference to safely continue the approach. For instance, landing clearance is necessary for entering the final phase of the landing but does not relate to visibility. A current ATIS report provides information on weather and airport conditions but doesn’t affect the pilot's immediate ability to see the runway. A functional altimeter is vital for altitude awareness during approaches but does not factor into visual reference requirements directly.