For an Instrument Landing System, which pair of antennas is essential to provide guidance?

For an Instrument Landing System, which pair of antennas is essential to provide guidance?

• A. VOR and DME
• B. Glide slope and localizer
• C. Localizer and glide slope reflector
• D. ADF loop and sense

Answer: (B)

The essential guidance for an ILS comes from two beams: the localizer for horizontal guidance and the glide slope for vertical guidance. The localizer antenna provides deviation from the runway centerline, helping you stay on track left or right of the extended runway centerline. The glide slope antenna delivers the descent path information, telling you whether you’re above or below the ideal glide path and by how much. Using both together gives you the precise final approach path to the runway in all weather. Other systems like VOR with DME offer enroute navigation and distance information, not the precise two-dimensional guidance needed for a safe instrument approach. An aerial described as a “glide slope reflector” isn’t a standard ILS component, and ADF loop and sense relate to non-ILS navigation.

The essential guidance for an ILS comes from two beams: the localizer for horizontal guidance and the glide slope for vertical guidance. The localizer antenna provides deviation from the runway centerline, helping you stay on track left or right of the extended runway centerline. The glide slope antenna delivers the descent path information, telling you whether you’re above or below the ideal glide path and by how much. Using both together gives you the precise final approach path to the runway in all weather.

Other systems like VOR with DME offer enroute navigation and distance information, not the precise two-dimensional guidance needed for a safe instrument approach. An aerial described as a “glide slope reflector” isn’t a standard ILS component, and ADF loop and sense relate to non-ILS navigation.