LNAV+V

[MartinJ]

Hi,

as we all know X-Plane's GNS 430/530 supports LNAV+V approaches. However when flying such an approach with the Saab there's no indication of the vertical path. Am I missing something or is the Saab not capable of indicating the vertical guidance provided by the GNS?

Kind regards

Martin 

[JGregory]

Martin,

I do not believe that the Saab's (vertical) indicator is coupled to the GPS.  Please provide the Airport and name of the LNAV+V approach you were attempting, so I can do some testing

[MartinJ]

Hi Jim,

I can highly recommend Palm Springs' (KPSP) RNAV RWY 31L approach.

[breadwild]

Martin, I think the approach into 13R is even more demanding (http://imageserver.fltplan.com/merge/merge1601/Single/00545RRY13R.PDF), and I've only been able to do the descent by dialing the altitudes in manual. I've never be able to make the Garmin do VNAV in any aircraft.

Brad

[JGregory]

Martn,

I would just like to be clear on what your reporting.  Do you simply want the vertical deviation to be displayed (similar to Glideslope)? or are you expecting VNAV functionality where the autopilot follows a vertical path?  The former would be reasonable, the latter not so much.

Edited February 1, 2016 by JGregory

[MartinJ]

@Brad: Thanks for the tip! I'll definitely try this approach next time. Should be fun flying it with the Saab. Garmin's VNAV isn't actually VNAV but a so called advisory vertical guidance. See this page for more information. As far as I can tell X-Plane's LNAV+V mode works very good. When LNAV+V becomes active and your CDI is coupled to your GNS you should see your glide slope needle starts moving and you can follow your glide path and course just like you would do with an ordinary ILS approach. If this doesn't work you are welcome to tell me which approach you are trying and we'll figure out why it's not working.

 

@Jim: What would be nice to have is the vertical guidance being displayed on the PFD as well as the possibility to follow the vertical guidance with the AP approach mode once LNAV+V becomes active. It's basically like flying an ILS approach but with the difference that the lateral and vertical path comes from the GNS.

Edited February 1, 2016 by MartinJ

[breadwild]

@MartinJ, Yes that approach is a challenge because it takes a more varied descent than simply a constant rate of descent, I've found. The Garmin or SAAB really don't have VNAV in the sense a fully equipped FMS would offer, where descents are targeted with waypoints. As far as the glide slope working as a flight director, I'm not sure that ever going to happen in this aircraft. Something like the JAR A320 has vertical and horizontal flight director bars that show the relationship of the aircraft to the programmed flight path. I think this is what you are asking for from Jim, but if the real aircraft doesn't have the feature, I can't see it being added here. Just my opinion.

It's interesting to not that KSPS doesn't have an ILS, but it really couldn't with the mountains poking out.

Brad

[^Wolf^]

@MartinJ I wish there was vertical deviation displayed on the EADI both on this sim and in real world. But even with SAAB 340A aircraft equipped with the Universal (UNS1k) FMS, you will find that vertical deviation is not displayed. 

Not sure if this is due to integration issues or cost issues or both.