The cone of confusion is defined as which of the following?

• A. The cone-shaped volume directly above a VOR station where no signal is received, causing the CDI to fluctuate.
• B. The region around a VOR with enhanced signal strength.
• C. The area around the runway where wind shear is likely.
• D. The volume above an ILS glide path where signals are filtered.

Answer: (D)

The concept here is how VOR navigation signals behave when you’re directly over the transmitting station. The cone of confusion is a cone-shaped volume directly above a VOR where the signal geometry makes it impossible for the receiver to determine a precise bearing. In this zone, the course deviation indicator can wander or flip because the aircraft’s position aligns with multiple possible radials, so the bearing information is unreliable. Once you move away from directly overhead, the bearing becomes clear again and the CDI stabilizes. So the description that locates this cone above the VOR station and notes that the CDI fluctuates best captures what's happening. The other descriptions refer to regions or systems (like wind shear near a runway or an ILS glide path) that aren’t related to the VOR bearing ambiguity.