LPV Glide Slope not working on Alabeo PA23 RXP GNS530 Install

[reanman]

The LPV Glideslope is not working on my RXP GNS530 install on my Alabeo PA23.  The GNS is connected to the HSI on the Alabeo PA23 and the glideslope works fine for a ILS approach with the GNS530 selected VLOC mode.  However on an LPV approach (with GPS mode selected on the GNS530), only the VCDI is functioning on the HSI and the GS is inactive (HSI GS off flag on).   

I noticed during the instrument check on the GNS530 on initial start up, the LCDI half left works fine on the HSI, but the GS flag still shows off and the VCDI check can not be confirmed (GS flag covers).  A HSI OBS adjustment check during the GNS530 initial startup checks also does work (OBS number does not change on GNS530).  However, the OBS adjustment works fine on the HSI during use.

Do I need to make a config file change to get the GPS vertical guidance to work properly on the HSI?  Or I am missing a switch setting on my Alabeo PA23 panel to enable? 

Any help would be appreciated.

reanman

[RXP]

Hi Reanman,

There are a number of discussions already in the RXP GNS FltSim forum. In short: besides enabling the corresponding links between the GNS V2 and the Instruments in the GUI Settings Panel, there is a chance the gauge developers didn't account for the possibility a GPS could drive the needle, since the default GPS does not...

[fppilot]

1 hour ago, reanman said:

The GNS is connected to the HSI on the Alabeo PA23 and the glideslope works fine for a ILS approach with the GNS530 selected VLOC mode. 

Does it couple with the autopilot for ILS? Or just show the vertical indicator on the HSI (for hand flown approach)?

[reanman]

Haven’t tried to fly an approach with the AP yet, just hand flying.  I will give the AP a try (ILS and LPV) and let you know when I get a chance 

[fppilot]

Appears that model’s AP ALT function is hold current altitude. Not follow variable setting. Most of those do not couple to vertical guidance.

[RXP]

It might be the case for most 'advanced' aircraft to try modelling so much beyond the SDK they might 'miss' the very basic cases, such as 'just tell me if there is a flagged condition or not on the vertical guidance, I won't outsmart the variables and think the default GPS is not capable of providing vertical guidance anyhow'.

Having said this, we're too busy in the GTN updates, the GNS updates and the work on the G600/500 to go deeper into these annoyances for now, but I'm sure once these big tasks are done, we'll be able to get into this and try to find out why is it some aircraft don't play nicely sometimes.

Now, all this just to celebrate my 2000th post in the forum! No 2K bug and champagne in order!

[reanman]

On further observation, the vertical guidance indicator on the HSI for my Alabeo PA23 is changing for the GPS input on an LPV approach, the GS unavailable flag is just covering it up (I can see the indicator changing under the flag).  The GS unavailable flag only goes away on and ILS approach...

If the GS unavailable flag issue on the HSI is not an easy fix, would it be easier to just switch the HSI to NAV2 and link the GPS to the Garmin OBS/GS gauge that NAV2 is currently using?  How would I do this?

 

[Flyfox]

Hi Reanman

In which area of the world are you experiencing this problem? I remember that LPV approaches do not work in Europe due to a limitation of the Garmin  GNS trainer or data base for this trainer.

[Bert Pieke]

3 hours ago, reanman said:

On further observation, the vertical guidance indicator on the HSI for my Alabeo PA23 is changing for the GPS input on an LPV approach, the GS unavailable flag is just covering it up (I can see the indicator changing under the flag).  The GS unavailable flag only goes away on and ILS approach...

If the GS unavailable flag issue on the HSI is not an easy fix, would it be easier to just switch the HSI to NAV2 and link the GPS to the Garmin OBS/GS gauge that NAV2 is currently using?  How would I do this?

 

Your key test is the the startup test page on your Garmin.

If the HSI has problems displaying the correct indications at that point, your approaches are not going to work correctly either.   If the HSI is not coded to accept the GPS vertical guidance, there is not much you can do, other than add a popup window window with a different HSI... not a very good solution in my book.

Suggest you ask Alabeo what is going on!

[RXP]

5 hours ago, Flyfox said:

I remember that LPV approaches do not work in Europe due to a limitation of the Garmin  GNS trainer or data base for this trainer

Hi, isn't this a limitation of the trainer shipping with our legacy GNS, but not anymore with our GNS V2 ?

[Flyfox]

14 hours ago, RXP said:

Hi, isn't this a limitation of the trainer shipping with our legacy GNS, but not anymore with our GNS V2 ?

Possibly yes. I can't check as I didn't upgrade to the GNS V2 yet. If so, its high time to upgrade now!

[RXP]

I've mistakenly thought LPV whereas GNS V2 Trainer adds this instead:

WAAS LP Approach Type Added
The WAAS LP Approach type and annunciation description has been added. LP approach capability is available for units with SW Version 3.30, or later.

Flying the LP Approach
An LP approach is flown the same as an LPV approach, except that vertical guidance is not provided. Angular scaling is similar to a localizer approach. Most LP approaches have step down altitudes associated with them.

1. Within 30 nautical miles of the destination, the 500W-series unit switches from en route mode to terminal mode and the CDI scale transitions from 2.0 to 1.0 nautical miles, full scale deflection.

2. As you approach the IAF, a turn direction message appears on the bottom of the screen.

3. As the distance (DIST) to the IAF approaches zero, the message is replaced by a time to turn advisory that counts down 10 seconds prior to the turn.

4. As you approach the FAF, the 500W-series unit will begin to automatically rescale in an angular fashion. This will allow the LP approach to be flown in the same fashion as a standard localizer approach. At 2.0 nautical miles from the FAF, CDI scaling is tightened from up to either 2° or 0.3 nautical miles, full scale deflection, whichever is smaller.
CTAF Symbol

5. Sixty seconds prior to reaching the FAF, the 500W-series unit will check the required Horizontal Alarm Limit (HAL) to ensure the GPS position integrity is within limits to complete the LP non-precision approach.
In the event the HAL limits are exceeded, the approach will be downgraded, when available, indicated by “LNAV” on the moving map, otherwise the approach will be aborted. A message will note that the approach is downgraded and the NAV indicator will be flagged. You may continue the approach using LNAV non-precision minimums if there are LNAV minimums for this approach. In the rare event the GPS HAL limits cannot meet non-precision limits, the 500W-series unit will notify the pilot with a message to abort the approach. The 500W-series unit will revert to terminal limits of 1.0 NM to support navigation to the missed approach.

6. As you cross the FAF, the destination sequences to the MAP. With the needle on the external CDI (or HSI) centered, fly toward the MAP, observing the altitude minimums dictated by the approach plate.

7. When viewing the Map Page, you’ll note that the final course segment is displayed in magenta (the active leg of the flight plan always appears in magenta).

8. As you approach the MAP, a waypoint message (“Arriving at Waypoint”) appears on the bottom of the screen.

9. At the MAP initiate the missed approach, if necessary. Once the 500W- series unit crosses the MAP sequencing will be suspended. Prepare the aircraft for missed approach operation. Press the OBS key to sequence to the Missed Approach procedure.

NOTE: For missed approaches with heading legs, fly manually until the first active course leg is reached, as described in earlier sections.

10. Fly the guidance provided by the 500W-series unit to the MAHP and hold.

CTAF Type Annunciation Added
The annunciation with a symbol for the CTAF type has been added to the WPT Airport Frequency page.

 

[reanman]

On ‎2‎/‎4‎/‎2018 at 3:52 PM, Flyfox said:

Hi Reanman

In which area of the world are you experiencing this problem? I remember that LPV approaches do not work in Europe due to a limitation of the Garmin  GNS trainer or data base for this trainer.

North America (Canada specifically)

[reanman]

On ‎2‎/‎4‎/‎2018 at 4:57 PM, Bert Pieke said:

Your key test is the the startup test page on your Garmin.

If the HSI has problems displaying the correct indications at that point, your approaches are not going to work correctly either.   If the HSI is not coded to accept the GPS vertical guidance, there is not much you can do, other than add a popup window window with a different HSI... not a very good solution in my book.

Suggest you ask Alabeo what is going on!

Yes, I believe Alabeo is my next stop.  Thanks for your thoughts.