What is the maximum range of a localizer used in an ILS approach?

The maximum range of a localizer used in an Instrument Landing System (ILS) approach is indeed established at 18 nautical miles (NM) from the antenna site. The localizer provides horizontal guidance during the approach by transmitting a radio signal that allows aircraft to align with the runway centerline.

The localizer's range is determined by regulatory standards and ensures that pilots have sufficient distance to intercept the final approach course safely, enabling accurate guidance as they descend toward the runway. At the maximum range of 18 NM, pilots can initiate their final approach sequence in a timely manner, allowing for appropriate altitude and speed management as they approach the runway environment.

Understanding this maximum range is crucial for pilots as they plan their descent and approach, ensuring they remain within the effective guidance area of the localizer and maintain situational awareness during the crucial phases of landing.