What is the purpose of an ILS test set?

• A. To calibrate weather sensors.
• B. To generate test signals for localizer and glide slope during maintenance and calibration.
• C. To measure runway lighting intensity.
• D. To communicate with air traffic control.

Answer: (B)

An ILS test set is used to inject controlled, known test signals into the Instrument Landing System’s ground transmitters to verify they are working correctly during maintenance and calibration. By generating signals that mimic what the localizer and glide slope should produce, technicians can check transmitter accuracy, alignment of the localizer course, the glide slope angle, signal strength, and overall system performance without needing an aircraft present. This targeted testing ensures the ILS provides proper guidance to approaching aircraft. It isn’t used for weather sensors, runway lighting measurements, or communications with air traffic control, which are separate systems.