LOs reference 062.02.05.01.03: Explain that marker beacons produce radiation patterns to indicate predetermined distances from the threshold along the ILS GP.

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Marker beacons are placed in a predetermined sequence before the threshold. The task of the markers is to produce a radiation pattern with a vertical beam upwards. By locating the markers at set distances before the threshold, the pilot can expect to fly above the markers at known distances. Consequently, the remaining distance from the final approach can be monitored. Therefore, we can say that the marker beacons indicate the aircraft’s horizontal position during the approach.