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RNAV equipment computes the rate of descent relative to the groundspeed; on some installations, it displays vertical guidance information on the GS indicator. When using this type of equipment during an instrument approach, the pilot must keep in mind that the vertical guidance information provided is not part of the nonprecision approach. Published nonprecision appr oach altitudes must be o bserved and complied with, unless otherwise directed by ATC. 

To fly to a WP using RNAV, observe the followi ng proce d ure [Figure 9-25] : 

1. Select the VOR/DME frequency. 

2. Select the  RNAV mode. 

3. Select the radial of the VOR that passes through the WP (225°). 

4. Select the distance from the DME to the WP (12 NM). 

5. Check and confirm all inputs, and center the CDI needle with the TO indicator showing. 

6. Maneuver the aircraft to fly the indicated heading plus or minus wind correction to keep the CDI needle centered. 

7. The CDI needle indicates distance off course of 1 NM per dot; the DME readout indicates distance in NM from the WP; the groundspeed reads closing speed (knots) to the WP; and the time to station (TTS) reads time to the WP. 

## VOR/DME RNAV Errors 

The limitation of this system is the reception volume. Published approaches have been tested to ensure this is not 

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a problem. Descents/approaches to airports distant from the VOR/DME facility may not be possible because, during the approach, the aircraft may descend below the reception altitude of the facility at that distance. 

## Advanced Technologies 

## Global Navigation Satellite System (GNSS) 

The Global Navigation Satellite System (GNSS) is a constellation of satellites providing a high-frequency signal that contains time and distance that is picked up by a receiver 

