An aircraft flying an approach to the right of the runway centerline will receive a localizer signal with what type of amplitude modulation?

An aircraft flying an approach to the right of the runway centerline will receive a localizer signal with what type of amplitude modulation?

• A. 45 Hz
• B. 90 Hz
• C. 120 Hz
• D. 150 Hz

Answer: (B)

The localizer signal, which is a component of the Instrument Landing System (ILS), is designed to provide lateral guidance for aircraft approaching a runway. When an aircraft is off the centerline, the localizer signal utilizes amplitude modulation to indicate the position relative to the runway. In general, the localizer broadcasts two signals that are modulated at different frequencies. The primary signal, indicating the centerline of the runway, is modulated at 90 Hz. As an aircraft deviates from the centerline—either to the left or right—the signal provides guidance through the difference in amplitude based on the position. Thus, if the aircraft is approaching to the right side of the runway, it will receive a stronger signal that confirms its position and helps guide it back towards the centerline, which is why 90 Hz is the appropriate answer for amplitude modulation in this scenario.

The localizer signal, which is a component of the Instrument Landing System (ILS), is designed to provide lateral guidance for aircraft approaching a runway. When an aircraft is off the centerline, the localizer signal utilizes amplitude modulation to indicate the position relative to the runway.

In general, the localizer broadcasts two signals that are modulated at different frequencies. The primary signal, indicating the centerline of the runway, is modulated at 90 Hz. As an aircraft deviates from the centerline—either to the left or right—the signal provides guidance through the difference in amplitude based on the position.

Thus, if the aircraft is approaching to the right side of the runway, it will receive a stronger signal that confirms its position and helps guide it back towards the centerline, which is why 90 Hz is the appropriate answer for amplitude modulation in this scenario.