Which VOR-related region causes unreliable indications when directly overhead the station?

• A. Cone of confusion
• B. Reverse sensing
• C. Line of sight
• D. DME arc

Answer: (A)

The cone of confusion is the region directly above a VOR where bearing indications become unreliable. When you’re right over the station, the signals used to determine your bearing are symmetric and there’s no single reference for the receiver to lock onto, so the CDI can flutter or show an incorrect direction. As soon as you move away from the overhead position, the bearing becomes reliable again. The other concepts aren’t a specific region that causes this overhead-unreliability: reverse sensing is a separate symptom that can occur near the station, line of sight is the general signal path, and a DME arc is a navigation route, not a region of unreliable indication.