As Glendale said, the 'cone of silence' was a term associated with the old radio ranges, where being left or right of track was indicated by audio 'dots' and 'dashes' rather than a visual display. It's modern equivalent is the 'cone(or area) of confusion' This is found in the area above a VOR, where the receiver cannot differentiate the signals from the transmitters to the extent required to determine the bearing.(Indicated by the 'OFF' flag showing on the indicator.)
If you are using the VOR on it's own,(without DME) then you must fly across the cone of confusion until you get a positive indication of station passage on the TO/FROM flag. Inevitably, this will mean that you will have to fly past the VOR, and then re-intercept the new track.
If you also have DME, you can use this to confirm that you are overhead the VOR, so long as you take into account the 'slant range' effect, in that when overhead, the DME will indicate the vertical distance from the beacon.(and will stop decreasing) You can also use the DME to anticipate the turn a little so that you roll out on the new track. This obviously, requires a reasonable estimate of the radius of turn.
MJ
