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vertical mode, you would just need to select the vertical speed (VS) and adjust the descent rate.
You can do this for NDB or VOR approach- es using the abovementioned procedures. It’s even easier if you have overlay op- tions, such as in the Rockwell Collins Pro- line 21 avionics package, to fly an NDB or VOR approach. The system allows you to re- ceive a computer-generated “Advisory Glide Path.” This glide path provides the appear- ance of an RNAV LPV or RNAV LNAV/ VNAV Glide Path but is advisory in nature. VOR and NDB approaches may be flown with the Flight Management System (FMS)
if they can be selected from the FMS database. The advan- tages should be obvious with more stabilized approach guidance and a computer-generated advisory glide path.
CDFA procedures get even easier when flying GPS-based approaches such as an LNAV with an MDA.
The same procedures and calculations above certainly apply, but you may not even need to calculate these in some systems that depict a computer-generated “Advisory Glide Path.” By selecting the Approach mode and the VNAV mode on the flight control panel, you will have vertical guidance as well as lateral guidance for the approach. Most modern
GPS approach capable systems, such as the Proline 21 and the Garmin 5000, do this as a native function and facilitate easy implementation of CDFA approach benefits on GPS- based approaches that do not have LPV glide slopes.
While technically not a “precision approach,” many modern avionics packages can also receive, depict, and operate LPV approaches. In approach terms, this is the latest and greatest addition to the RNAV approach cat- egory. The Localizer Performance with Vertical Guidance (LPV) approach generates a vertical Glide Path using a WAAS-generated glide path. This system provides a
6 • TWIN & TURBINE / September 2023