Instrument Rating Checkride Practice Test

How is the service volume of the localizer defined?

1. 5 NM within 35 degrees

2. 10 NM within 35 degrees

3. 15 NM within 10 degrees

4. 20 NM within 5 degrees

The correct answer is: 10 NM within 35 degrees

The service volume of a localizer is a critical component when considering instrument approaches in aviation. The correct definition of a localizer's service volume is that it extends 10 nautical miles from the antenna and within a 35-degree lateral area. This means that within this specified distance and angle, a localizer can provide reliable course guidance to pilots navigating an approach. The localizer transmits very high frequency (VHF) signals that help pilots maintain the correct landing approach path. Understanding the service volume is essential for pilots because it directly impacts the accuracy and reliability of the navigational information they receive when approaching the runway. Being aware of this range allows pilots to effectively use the localizer to ensure they are on the right flight path during an ILS (Instrument Landing System) approach.