Which NAVAIDs are primarily in use in the United States?

• A. Non-Directional Beacon and Very High Frequency Omni-directional Range
• B. GPS and GLONASS
• C. DME and TACAN
• D. ILS and MLS

Answer: (A)

NAVAIDs are ground-based radio navigation aids that pilots use for enroute and procedure navigation. In the United States, the most widely used of these are the VORs and NDBs. A VOR provides accurate azimuth information, allowing pilots to fly defined courses and airways with confidence. An NDB, using an ADF, gives a bearing to the beacon, serving as a simple, widely available back-up and helping with navigation in areas where more precise VOR coverage isn’t available.

GPS and GLONASS are satellite-based navigation systems, not ground-based NAVAIDs. DME and TACAN supply distance information (and are often paired with VOR or TACAN stations) rather than serving as the primary bearing sources on their own. ILS and MLS are landing aids used for precision approaches, not general enroute navigation. So the two most representative, primary ground-based NAVAIDs used in the US are the non-directional beacon and the VOR.