Rman

Carenado S550 Citation V Nav Constraints.

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While flying the Carenado S550 Citation; using the RXP GTN 750 I am unable to get the V NAV to fly the altitude constraints as indicated in the flight plan. 

When I disable the GTN 750 and instead use the stock X-Plane FMS the V NAV works fine. Is this plane capable of flying V NAV with the GTN 750?

Regards,

Bob

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Hi,

AFAIK the GTN is not capable of coupling VNAV altitude. I couldn't find any contrary mentions in the Garmin GTN Pilot's Guide either, thus I guess this is normal. Any real life GTN pilot might probably shed some light to this?

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Posted (edited)

Correct...the altitudes are only there for advisory and situational awareness.  I see a mention of VNAV but I don't think it actually couples to your AP and flies the constraints on the chart....  I believe in the latest revision you can set an altitude and you'll get a required descent rate like VSR that we already have in the sim version.

Where's David when you need him?

EDIT:  Well actually I'm not so sure...  the newest update to the real GTN may have VNAV support....  looking at this video makes me wonder:

https://www.youtube.com/watch?v=11tmUcvrwKo

Also from the latest pilot's upgrade supplement (GTN 725/750)

4.3.3 En Route Vertical Navigation

NOTE: This feature is available in software v6.50 and later.

The vertical navigation (VNAV) feature provides vertical profile guidance during the descent phase of flight. Guidance is based on altitude constraints associated with lateral waypoints in the active flight plan.

Functions:

• Presents vertical path guidance to the descending path as either a line joining two waypoints with specified altitudes or a linear deviation from the desired path (i.e., the vertical angle from the specified waypoint or altitude)

• Integrates vertical waypoints into the active flight plan

 Supports both manual and autopilot coupling

4.3.3.1 VNAV Requirements

 Enablement by the installer

• A baro-corrected altitude source

If en route vertical navigation is not enabled, the GTN provides a single waypoint vertical calculator. For more information, refer to section 15.1. For installation details related to en route vertical navigation, consult the AFMS.

 

Edited by ryanbatcund

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@Paulvanuf The genuine RealityXP GTN 750/650 Touch offers VNAV functions (when using GTN Trainer 6.50+).

The Reality XP GTN Aircraft Flight Manual Supplement (AFMS) settings offer the choice between VNAV and VCALC.

The VNAV function works perfectly fine and guides you through vertically in your flight plan but it is not coupled to the autopilot. 

Besides, LPV and its derivatives are vertically coupled with he autopilot for landing.

 

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37 minutes ago, RXP said:

@Paulvanuf Besides, LPV and its derivatives are vertically coupled with he autopilot for landing.

 

Sorry,

”LPV and its derivatives”?

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5 minutes ago, Paulvanuf said:

Sorry,

”LPV and its derivatives”?

LNAV+V

  • Like 1

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1 hour ago, Paulvanuf said:

Hi Paul,

😊

This may help a bit more:

http://www.aviationsafetymagazine.com/issues/36_4/features/RNAV-Approach-Types_11164-1.html

 

Quote

- LPV: Localizer performance with vertical guidance. Offers localizer accuracy and a WAAS-based glideslope, like an ILS. Also like an ILS, lateral sensitivity increases as the aircraft approaches the runway. Minimums are published as a decision altitude (DA).

- LNAV/VNAV: Lateral/vertical navigation. Unlike an LPV procedure, lateral sensitivity does not increase as the aircraft nears the runway. Glideslope information is based on WAAS or barometric altitude. Minimums are published as a DA.

- LNAV: Lateral navigation. Similar to an LNAV/VNAV procedure except no glideslope is presented. Sensitivity does not increase as one nears the runway. Minimums are a minimum descent altitude (MDA), as with a VOR or localizer-only procedure.

- LP: Localizer performance. No vertical guidance provided. Sensitivity increases as the aircraft nears the runway, as with a traditional localizer. Minimums are an MDA.

- Stand-Alone GPS: The old-style GPS approach is basically an LNAV procedure but restricted to using only GPS. Offers an MDA.

 

Regards,

Scott

Edited by scottb613
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Thx Scott,

I have a lot to learn. Still hesitating to buy the rxp750 to fly with the Carenado Cit s550

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Hi Paul,

Happy to help - while I’m on the other side of the fence - P3D - I find the GTN essential - as it brings realistic navigation to so many aircraft  - not sure if the Citations ever used them for real.

Yep - the learning can be fun and it’s what differentiates a sim from a game - best of luck whatever you choose to do.

Regards,

Scott

  • Like 2

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