If visibility falls to 1500' outside of the FAF, what should you do?

When visibility decreases to 1500 feet outside of the Final Approach Fix (FAF), executing a missed approach is the appropriate response. This action is taken to ensure safety when the visibility is below the minimums required for the approach being flown.

In typical instrument approach procedures, there are specific visibility requirements that must be met to continue safely to landing. If those visibility requirements are not met, conducting a missed approach prevents the risk associated with attempting to land in conditions that may not allow for a safe arrival, such as inability to see the runway or surrounding environment.

Continuing the approach would compromise safety since visibility is inadequate. Similarly, requesting a lower altimeter setting does not address the issue of poor visibility and would not necessarily improve the situation. Circling to land is typically used in different contexts, where visibility may be adequate for maneuvering but isn't the correct response when overall visibility is severely restricted. Thus, executing a missed approach is the recommended action in this scenario for the pilot's safety and the safety of the aircraft and its passengers.