What is the safety concern regarding ILS/NAVAIDs during ARFF operations?

• A. NAVAIDs guide aircraft; do not park where an ARFF vehicle blocks the ILS signal to incoming aircraft.
• B. NAVAIDs are not affected by ARFF operations.
• C. ARFF vehicles should always park on or near the ILS signal.
• D. GPS signals replace ILS during emergencies.

Answer: (C)

The safety concern is keeping navigation aids unobstructed and interference-free during ARFF operations. The ILS provides critical guidance to aircraft on approach, and anything that blocks or sits in the signal path can distort the localizer or glide-slope signals, or create reflections that mislead pilots. Large ARFF vehicles and equipment are metallic and can physically block the antenna array or affect the radio signals, degrading approach accuracy or causing a false sense of guidance. Because of this, ARFF responders should position vehicles away from the ILS signal areas to preserve a clean, reliable approach for landing.

GPS does not replace the ILS during emergencies, and NAVAIDs remain susceptible to obstruction or interference from nearby equipment. So the prudent practice is to keep the ILS and other navigational aids clear of parked ARFF equipment to maintain safe, predictable landings.