Cone of Confusion

As the VOR is approached, the radials converge and the VOR needle becomes more sensitive. Overhead the VOR the CDI may oscillate rapidly and the ‘OFF’ flag may appear momentarily. Also the ‘TO/FROM’ display alternates. This zone of confusion is caused by a lack of adequate signal directly above the station due to the radiation pattern of the station’s antenna, and because the resultant of the opposing reference and variable signals is small and constantly changing.