FAA Instrument Rating Airplane (IRA)Navigation SystemsEasy
During an ILS approach, a pilot observes a blue marker beacon light illuminate accompanied by a low-pitched tone of continuous dashes. Which ILS component has the aircraft just passed?
- AThe final approach fix marker
- BThe inner marker
- CThe middle marker
- DThe outer marker
Show answer & explanationAnswer & explanation
Correct answer: D. The outer marker
The outer marker is identified by a blue light and a low-pitched audio tone of continuous dashes at a rate of about two per second, indicating the aircraft is at the approximate point where an aircraft would intercept the glide slope.
Why the other options are wrong
- A. There is no ILS component called the 'final approach fix marker'.
- B. The inner marker uses a white light with continuous dots and is used mainly for Category II/III operations.
- C. The middle marker uses an amber light with alternating dot-dash tones.
ILS Marker Beacons
Marker beacons transmit vertically along the ILS approach path and are identified by distinct colors and tones as the aircraft crosses them.
- Outer marker: blue light, low tone, dashes
- Middle marker: amber light, alternating dot-dash
- Inner marker: white light, continuous dots
Memory trick: 'Blue is far, Amber is near, White is here.'