Instrument Rating Checkride Practice Test

What element of the ILS is susceptible to errors caused by reflection?

1. Localizer

2. Glide slope

3. Marker beacons

4. Runway lights

The correct answer is: Localizer

The localizer component of the Instrument Landing System (ILS) is susceptible to errors caused by reflection because it utilizes radio signals transmitted from the ground to guide aircraft laterally during their approach to the runway. Reflection can occur when these signals bounce off nearby terrain, buildings, or even other aircraft, leading to interference and distortion of the intended signal. This can result in a misalignment of the displayed localizer deviation, causing pilots to receive inaccurate lateral guidance during their approach. In contrast, the glide slope is focused on vertical guidance and is less likely to be impacted by reflections. Marker beacons are positioned on the approach path to provide exact location information, and runway lights serve primarily as visual aids for orientation without being significantly affected by reflections. Therefore, while ILS components play crucial roles in landing, the localizer is distinct in its vulnerability to errors induced by reflective obstacles.