What is the valid ILS localizer coverage area between 10-18 nautical miles from the transmitter?

The valid ILS localizer coverage area between 10-18 nautical miles from the transmitter is indeed typically 10 degrees either side of the course centerline. This is important because it defines the lateral limits of the localizer's signal, which is crucial for maintaining proper alignment with the runway during an instrument approach.

The use of a 10-degree coverage area reflects the design and operational standards for localizers, which are intended to provide precise guidance to aircraft as they approach the runway. By ensuring that aircraft remain within this narrow beam, the risk of navigation errors is minimized, allowing for safe and accurate landings, particularly in poor visibility conditions.

Understanding the localizer's coverage area is vital for pilots, as it helps them maintain situational awareness and ensures adherence to instrument approach procedures. This knowledge also aids in making proper decisions during the approach, as exceeding this coverage area could result in a loss of signal or incorrect positioning relative to the runway, impacting the safety of the approach and landing.