Marker beacons on the ILS use which frequency?

Marker beacons on the ILS use which frequency?

• A. 108 to 112 MHz
• B. 329 to 335 MHz
• C. 75 MHz
• D. 400 to 450 MHz

Answer: (C)

Marker beacons along an ILS operate on a fixed 75 MHz carrier. This dedicated frequency is separate from the ILS localizer band around 110 MHz and other aviation bands, and it’s what your cockpit marker detector tunes to in order to identify when you’re at the outer, middle, or inner marker. Each marker also uses distinct audio tones to further distinguish which marker you’ve reached (outer with one tone, middle with another, inner with another). So the frequency used by the marker beacons is 75 MHz.

Marker beacons along an ILS operate on a fixed 75 MHz carrier. This dedicated frequency is separate from the ILS localizer band around 110 MHz and other aviation bands, and it’s what your cockpit marker detector tunes to in order to identify when you’re at the outer, middle, or inner marker. Each marker also uses distinct audio tones to further distinguish which marker you’ve reached (outer with one tone, middle with another, inner with another). So the frequency used by the marker beacons is 75 MHz.