Phantom Waypoints RNAV
Phantom waypoints are points in space that are created with reference to ground stations. For example, a phantom waypoint might be created 10 miles to the east of a VORVOR —VHF Omnidirectional Range/DMEDME —Distance Measuring Equipment. Using RNAVRNAV —Radio Navigation equipment, the aircraft can then fly to this point in space without having to fly to the VORVOR —VHF Omnidirectional Range/DMEDME —Distance Measuring Equipment and then outbound to it.
Fairly obviously, the aircraft cannot use the phantom waypoint if the reference station is not in range, because the aircraft equipment would not know where the reference station was to project the phantom waypoint. However, you can input the data before being in range - this will save time in the air.