What routine checks are performed on an ILS glide slope transmitter?

• A. Visual inspection.
• B. Alignment verification.
• C. Visual inspection, alignment verification, transmitter power check, failure diagnostics, and calibration per maintenance schedule.
• D. Wind noise measurement.

Answer: (C)

Routine maintenance of an ILS glide slope transmitter must verify operation across several critical dimensions to keep vertical guidance accurate and safe. Visual inspection catches obvious physical issues—damaged enclosures, loose connections, corrosion or wildlife damage that can affect performance. Alignment verification ensures the transmitter’s antenna pattern is correctly aimed and centered, since even small misalignment can skew the glide slope reference and mislead landings. Transmitter power check confirms the output remains within specification, catching drift that could alter the signal depth and integrity. Failure diagnostics pull fault codes and test the transmitter chain to detect faults that aren’t visible, ensuring any degraded components are identified before they impact service. Calibration per the maintenance schedule maintains the accuracy of reference levels, modulation, and other parameters so the system stays within required tolerances.

This combined approach is necessary because relying on just one or two checks could miss issues that only arise when multiple systems interact—visual inspection alone might miss electrical drift or alignment errors, and measuring wind noise has no bearing on RF transmitter health. The comprehensive set aligns with standard preventive maintenance practices for critical navigation aids, ensuring the glide slope remains reliable for safe approaches.