What obstacle clearance do Minimum Sector Altitudes provide?

Minimum Sector Altitudes (MSA) are designed to ensure a level of obstacle clearance for aircraft in a given sector around a navigation aid. The correct choice indicates that MSAs provide a vertical clearance of 1,000 feet within 25 nautical miles (NM) of the navigating aid. This altitude serves as an important safety measure, allowing pilots to safely maneuver in the vicinity of the navigation aid while avoiding potential obstacles, like terrain or man-made structures, that may pose a risk to flight.

The reason for this particular clearance distance reflects the aviation industry's commitment to maintaining safety margins during flight operations. By providing a clearance of 1,000 feet within 25 NM, pilots are assured of a protective buffer around the navigation aid that can accommodate typical variations in terrain and help further ensure safe navigation during approaches and departures.

Option B's specifications are structured based on FAA standards and contribute to standardized practices for pilots flying in the vicinity of a navigational aid, ensuring a consistent level of safety across various flight environments. Other options offer different altitudes and distances that do not align with the established safety benchmarks for Minimum Sector Altitudes, thereby making them less suitable in this context.