Pilots of GA piston singles don’t typically fly STARs, and usually ATC vectors us to join approaches that don’t require many step-downs as we intercept the final approach course. Instead, we tend to use the VNAV (or older VCALC) features in our avionics to meet crossing restrictions, manage the descent from cruise to an initial altitude for an approach, or to help us arrive near an airport at the appropriate traffic pattern altitude.
But when connected to a GPS navigator, such as a Garmin GTN 750 or 650, that supports vertical navigation, new digital autopilots like the Garmin GFC 500 and GFC 600 can automatically descend as you fly the initial legs of an instrument approach, reducing your workload and helping you spend more time monitoring your progress.
To watch VNAV fly a series of published step-downs, join me as I fly the RNAV (GPS) RWY 29 approach at the Skagit Regional airport (KBVS) north of Seattle, an approach that shows the value of using VNAV. I’m in my Beechcraft A36 equipped with the GFC 600 autopilot, a GTN 750Xi, and G500 TXi.
For more information about VNAV, see these additional posts here at BruceAir:
One of the terrific features available in the latest digital autopilots is VNAV, or vertical navigation. If you have a Garmin GTN-series navigator and a GFC 500 or GFC 600 autopilot, you can use VNAV to descend to the charted altitudes along the intermediate legs of an instrument approach, until you reach the final approach fix.
VNAV is also available on most G1000 systems equipped with the GFC 700 autopilot, including the new G1000 NXi, and some other manufacturers, such as Avidyne, plan to add the feature to their systems.
The 10-minute video below demonstrates how VNAV can help you fly a smooth, precise descent prior to the FAF. The video explains the basic concepts, uses the Garmin PC Trainer Suite to highlight key details, and then shows VNAV at work as I fly the RNAV (GPS) RWY 12 approach at Kelso, WA (KKLS).
For more information about VNAV, see Garmin GTN VNAV here at BruceAir. Garmin has also posted a detailed explanation of VNAV in the following video.