Name three key components of an ILS approach and their function.

• A. Localizer (lateral guidance), Glideslope (vertical guidance), Outer/Center/Inner markers (position cues along the approach).
• B. VOR, DME, ADF.
• C. Localizer, Glidepath, and Weather Radar.
• D. Glideslope, Localizer, and ILS frequency lock.

Answer: (A)

An ILS approach is built on providing guidance in three parts: horizontal guidance, vertical guidance, and fixed distance cues along the approach.

The Localizer gives lateral guidance, aligning the airplane with the runway centerline so you stay on the correct horizontal path as you descend. It’s the left-right guidance that keeps you centered on the runway axis.

The Glideslope delivers vertical guidance, showing you whether you’re above or below the ideal descent path and by how much. Following the glide path keeps you on a steady 3-degree descent to the runway threshold.

Markers—outer, middle, and inner—provide distance cues along the approach. They indicate when you’re at key points on the path, helping confirm intercept with the localizer and glide slope, and in some operations near the runway they also serve as a cue for the final portion of the approach.

Together, these three elements—localizer for side-to-side alignment, glideslope for vertical descent, and markers for position cues—form the core of an ILS approach.