Which marker beacon is Blue and marks the glide slope intercept?

• A. Outer Marker is Blue and indicates the glide slope intercept with a low-pitched tone
• B. Middle Marker is Blue and indicates the FAF
• C. Inner Marker is Blue and indicates CAT II DH
• D. Marker beacons do not use color coding

Answer: (A)

Marker beacons along an ILS are color-coded to help you identify position on the approach. The blue outer marker sits on the final approach course and marks the point where you intercept the glide slope. It’s accompanied by a low-pitched tone, signaling that you’ve reached the glide slope intercept point. The middle marker is amber and marks the final approach fix, with a higher-pitched tone, and the inner marker is white, indicating CAT II/III decision height. Since the blue beacon that marks the glide slope intercept with a low-pitched tone is exactly described, that choice is correct.