What type of ground-based radio navigation system is commonly used?

The choice of VOR as the correct answer reflects its widespread use in the aviation community as a ground-based radio navigation system. VOR, or VHF Omnidirectional Range, is designed to provide aircraft with a reliable means of determining their position and maintaining their desired path. It operates by broadcasting a VHF radio signal from a fixed location on the ground, allowing pilots to receive directional guidance in relation to the station.

VOR systems are integral for en route navigation as they offer a precise method for pilots to navigate along specific airways and approach procedures. With the ability to provide both course guidance and distance information when paired with a Distance Measuring Equipment (DME) system, VOR is essential for improving flight safety and efficiency.

In comparison, other navigation systems serve different purposes. GPS, for example, is a satellite-based global navigation system that, while widely used, does not qualify as a ground-based system. NDB, or Non-Directional Beacon, is another type of navigation facility but provides less precision and is considered somewhat obsolete due to advancements like VOR and GPS. ILS, or Instrument Landing System, is specialized for approach and landing, focusing on providing guidance in the final stages of flight rather than general navigation. Thus, while these