What does prevailing visibility indicate?

Prevailing visibility is defined as the greatest distance at which objects can be seen and identified over at least half the horizon, typically in a horizontal plane. This measurement is crucial for pilots and air traffic controllers because it provides a standardized way to assess the visibility conditions in the area where an aircraft is operating.

In practical terms, prevailing visibility helps to determine how far a pilot can safely see other aircraft, obstacles, and other relevant features during flight. This is essential for both takeoffs and landings, as well as during navigation under visual flight rules (VFR).

The other choices do not accurately capture the concept of prevailing visibility. While maximum distance or visibility around the aircraft can consider sudden visibility variances, prevailing visibility focuses on an aggregate measure across a broader perspective, providing a consistent baseline for safety assessments. Additionally, prevailing visibility is not a fixed distance; it can change based on environmental conditions, making it a dynamic measurement rather than a static one.