Definition
A small, cone-shaped volume of airspace directly above a VOR or VHF omnirange station in which the station's signal cannot be reliably received. As an aircraft passes over the station, the navigation receiver loses a usable signal momentarily, causing the course indicator and TO/FROM flag to fluctuate until the aircraft is clear of the cone on the other side.
Plain English
A small patch of sky directly above a ground-based navigation station where the signal briefly drops out. As you fly over the station, your navigation needle wobbles for a few seconds, then settles again once you're past it.
Context Anchor
Seen when tracking to or passing over a radio navigation station during instrument navigation.
Derivation
Called a 'cone' because the dead-signal zone is shaped like an upside-down cone with its point at the station and widening with altitude. 'Confusion' refers to the navigation indicator's behavior — the needle and flags become erratic and unreliable while the aircraft is inside this zone.
Why Pilots Care
Recognizing passage through this zone prevents misinterpreting normal instrument fluctuations as a navigation failure or course deviation.
Grounding Statement
As the airplane passes over the station, the indication may wobble, swing, or change briefly, then settle again after the aircraft has moved away from directly overhead.
Intuition Check
Do not read “confusion” as a pilot’s mental state here. It means the navigation signal or indication is temporarily unclear near the station.
Example Sentence 1
As they crossed over the VOR, the course needle swung wildly through the cone of confusion, then settled on the outbound radial.
Example Sentence 2
The pilot maintained heading through the cone of confusion until the instruments stabilized on the far side of the station.