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

The symbol on an Instrument Landing System (ILS) or Localizer (LOC) procedure represents a minimum safe sector altitude within 25 nautical miles. This altitude is crucial because it provides a safe margin above terrain and obstacles, ensuring that an aircraft can operate safely as it approaches the runway. The minimum safe sector altitude is designed to enhance safety by offering pilots a clearly defined altitude to maintain, especially in areas where there might be varying terrain or obstacles.

Understanding this altitude is key for pilot decision-making, especially during the approach phase of flight. It helps ensure that the aircraft remains safely above any potential obstructions while still allowing for vertical navigation to the runway.