FAA Instrument Flight Instructor (FII)Instruments and SystemsEasy
While briefing a student on ILS approach components, a CFII asks which marker beacon is identified by a blue light and a continuous series of low-pitched (400 Hz) dashes as the aircraft crosses it?
- ABack Course Marker
- BInner Marker
- CMiddle Marker
- DOuter Marker
Show answer & explanationAnswer & explanation
Correct answer: D. Outer Marker
The Outer Marker is identified by a blue cockpit light and a continuous series of low-pitched dashes at 400 Hz, and it marks the point where the glide slope is normally intercepted for final approach. The Middle Marker uses amber light with alternating dot-dashes at 1300 Hz, and the Inner Marker uses white light with continuous dots at 3000 Hz.
Why the other options are wrong
- A. Back course markers are not standard equipment identified by this tone/color combination.
- B. The Inner Marker uses white light and 3000 Hz continuous dots.
- C. The Middle Marker uses amber light and 1300 Hz alternating dot-dashes.
Marker Beacons
Ground-based transmitters along the ILS course that provide distinctive lights and audio tones in the cockpit to identify specific points along the approach.
- Outer Marker: blue light, 400 Hz continuous dashes
- Middle Marker: amber light, 1300 Hz alternating dot-dash
- Inner Marker: white light, 3000 Hz continuous dots
Memory trick: Blue sky is far Out, Amber is in the Middle, White is nearly In (the runway)