The symbol on an ILS or LOC procedure represents what within 25 NM?

The symbol on an ILS (Instrument Landing System) or LOC (Localizer) procedure that is relevant within 25 nautical miles is representative of a minimum safe sector altitude. This altitude serves as a safety measure, ensuring that aircraft remain well above terrain and obstacles in the surrounding area as they prepare for their approach and landing. It provides pilots with vital information to maintain a safe altitude during the operational phases of an approach, especially when they might not have visual contact with the ground.

Minimum safe sector altitudes are designed specifically for procedures like the ILS or LOC, allowing pilots to navigate the approach safely, even under challenging visibility conditions. These altitudes are calculated based on the surrounding topography and provide a buffer to enhance safety margins prior to reaching the approach fix.

The significance of this altitude underlines the importance of being aware of terrain and other potential hazards as pilots execute their approach, particularly in areas that might have significant altitude variations. Therefore, understanding and adhering to the minimum safe sector altitude is crucial for safe flight operations in this context.