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-   -   Enroute VNAV - Skyview and GTN 650 (https://vansairforce.net/community/showthread.php?t=173048)

bmarvel 07-05-2019 06:35 PM

Enroute VNAV - Skyview and GTN 650
 
I previously posted my concerns about compatibility between a box made by one manufacturer and a related box made by another. In the case at hand, the two are the Skview display/autopilot and the GTN 650 in my RV-14A. Specifically, they have worked just fine for 450 hours in flying both ILS and LPV approaches. The problem is with enroute VNAV, which came about with Garmin?s 6.51 and 6.62 software upgrades. I have never been able to get the Skyview system to ?see? enroute VNAV from the 650 or to fly it and wonder if anyone else has the same problem or a solution. I've previously sent this to Dynon but without a resolution. Again, this is not regarding approaches as they work well. It just involves enroute VNAV.

To frame this better for you, I'll indicate below what the 650 does regarding enroute VNAV versus what my Skyview system does with that same data:

650

1. Assume I get this ATC directive when eastbound: descend to cross 10 west of ABC at and maintain 7000 feet.
2. In the 650 I select the ABC fix, select 10 miles short of it and enter this new point in the flight plan.
3. I then select the altitude block for this point, put in 7000, set a desired descent rate and press save.
4. The 650 moving map now shows the new fix, the top of descent (TOD) point and the bottom of descent (BOD) point based on my chosen descent rate and the ground speed.
5. As the aircraft approaches TOD on the 650 moving map, a countdown timer indicates how many minutes and seconds there are before the descent should start.
6. Once TOD is reached, the timer resets to show how many minutes and seconds remain until BOD.
7. All of the above works every time in the 650 as it computes and displays this descent.

What Skyview (SV) does after the above 650 set up is complete

1. The letters ATK (for along track) appear on the SV screen 10 miles west of ABC.
2. No TOD or BOD points are shown on the SV screen.
3. With my SV autopilot on nav and altitude hold I set 7000 into the altitude pre-select window for the crossing altitude.
4. I press VNAV on the autopilot control panel and nothing changes. I do not get the down arrow showing the autopilot is armed to capture VNAV as it does when I am on an ILS or LPV and select VNAV for glideslope capture.
5. The aircraft remains at cruise altitude as the 650 countdown timer and 650 moving map both show it approaching the TOD point, which is indicated on the 650 screen but not on the SV screen. The aircraft then continues past the TOD point on the 650 but never leaves cruise altitude even though the 650 is now counting down minutes and seconds to the BOD point.
6. The aircraft continues on past the BOD point on the 650 display still at cruise altitude.
7. SV never does anything in response to this VNAV setup on the 650. It is as though no vertical nav data from the 650 is reaching the Skyview autopilot or if it does reach SV, the autopilot does not respond to it.

I can manually command a vertical descent rate using the SV autopilot and monitor the aircraft to keep it near the 650's computed descent profile but I cannot get the autopilot to do that and it should.

If there is something I need to do differently regarding button pushing sequence and the like I would like to know as nothing I have tried will work. I cannot believe I am the only SV owner with a 650 who has this problem.

Don Jones 07-05-2019 08:34 PM

Quote:

Originally Posted by bmarvel (Post 1357404)
I previously posted my concerns about compatibility between a box made by one manufacturer and a related box made by another. In the case at hand, the two are the Skview display/autopilot and the GTN 650 in my RV-14A. Specifically, they have worked just fine for 450 hours in flying both ILS and LPV approaches. The problem is with enroute VNAV, which came about with Garmin?s 6.51 and 6.62 software upgrades. I have never been able to get the Skyview system to ?see? enroute VNAV from the 650 or to fly it and wonder if anyone else has the same problem or a solution. I've previously sent this to Dynon but without a resolution. Again, this is not regarding approaches as they work well. It just involves enroute VNAV.

To frame this better for you, I'll indicate below what the 650 does regarding enroute VNAV versus what my Skyview system does with that same data:

650

1. Assume I get this ATC directive when eastbound: descend to cross 10 west of ABC at and maintain 7000 feet.
2. In the 650 I select the ABC fix, select 10 miles short of it and enter this new point in the flight plan.
3. I then select the altitude block for this point, put in 7000, set a desired descent rate and press save.
4. The 650 moving map now shows the new fix, the top of descent (TOD) point and the bottom of descent (BOD) point based on my chosen descent rate and the ground speed.
5. As the aircraft approaches TOD on the 650 moving map, a countdown timer indicates how many minutes and seconds there are before the descent should start.
6. Once TOD is reached, the timer resets to show how many minutes and seconds remain until BOD.
7. All of the above works every time in the 650 as it computes and displays this descent.

What Skyview (SV) does after the above 650 set up is complete

1. The letters ATK (for along track) appear on the SV screen 10 miles west of ABC.
2. No TOD or BOD points are shown on the SV screen.
3. With my SV autopilot on nav and altitude hold I set 7000 into the altitude pre-select window for the crossing altitude.
4. I press VNAV on the autopilot control panel and nothing changes. I do not get the down arrow showing the autopilot is armed to capture VNAV as it does when I am on an ILS or LPV and select VNAV for glideslope capture.
5. The aircraft remains at cruise altitude as the 650 countdown timer and 650 moving map both show it approaching the TOD point, which is indicated on the 650 screen but not on the SV screen. The aircraft then continues past the TOD point on the 650 but never leaves cruise altitude even though the 650 is now counting down minutes and seconds to the BOD point.
6. The aircraft continues on past the BOD point on the 650 display still at cruise altitude.
7. SV never does anything in response to this VNAV setup on the 650. It is as though no vertical nav data from the 650 is reaching the Skyview autopilot or if it does reach SV, the autopilot does not respond to it.

I can manually command a vertical descent rate using the SV autopilot and monitor the aircraft to keep it near the 650's computed descent profile but I cannot get the autopilot to do that and it should.

If there is something I need to do differently regarding button pushing sequence and the like I would like to know as nothing I have tried will work. I cannot believe I am the only SV owner with a 650 who has this problem.

Bill,
Currently SkyView does not have VNAV capability outside of instrument approaches. It is strictly altitude hold and any altitude changes must be done manually. Full VNAV is a planned feature that should come out in an update in the near future, barring any unforeseen issues, so stay tuned....

wnplt 07-06-2019 12:10 AM

Same problem here. Enroute VNAV is Garmin proprietary and will not work unless you have a Garmin EFIS. Heard it might be coming to third party but don?t hold your breath.

bmarvel 07-06-2019 07:24 AM

Quote:

Originally Posted by Don Jones (Post 1357424)
Bill,
Currently SkyView does not have VNAV capability outside of instrument approaches. It is strictly altitude hold and any altitude changes must be done manually. Full VNAV is a planned feature that should come out in an update in the near future, barring any unforeseen issues, so stay tuned....

Don, this is astonishing! While I appreciate the very concise answer, why wasn't I told that when I reported this problem to Dynon last September -- 9 months ago? In the back and forth that ensued, nothing was said about Skyview being unable to support enroute VNAV. Just a week ago when I provided additional information to the company on what I was seeing, I received a diagram back showing the ARINC wiring and configuration settings and asked to reconfirm those. The implication is that at least one person there was unaware of the Skyview limitation you just revealed. While I understand the focus has been on certification work on the HDX, it is disheartening to see this communications lapse occur. I'm disappointed.

jeffkersey 07-06-2019 08:06 AM

Similar issue...
 
I have the same issue with my Trutrak Gemini. It will shoot LPV approaches from the GTN650 but not enroute VNAV. Hopefully they will get it all working in the future.

rleffler 07-06-2019 04:06 PM

I believe all third party EFIS vendors are in the same boat. They need to reverse engineer this new feature from Garmin and then implement new code for it.

I have AFS and I?m sure some of the other other EFIS vendors have sold military capabilities using an internal flight plan, but then you have to switch back to the 650 flight plan to shoot the approach.

Personally I?m comfortable with the altitude hold for enroute while using the 650 flight plane until AFS can implement this capability.

Carl Froehlich 07-06-2019 05:47 PM

I have been surprised at the anguish in this thread over what I see is little more than a marketing tool. I have flown a lot of IFR with the SkyView and GTN-650 and do not find changing the autopilot altitude setting as too arduous.

Carl

Walt 07-06-2019 06:03 PM

I think its more than marketing.

Being able to cross a fix (or multiple fixes) at a precise altitude takes the guess work out of when to start the decent and allows increased precision during the approach phase of the flight. Also STARs are now loaded with the step downs as well.

Something that I like quite a bit is being able to setup multiple fixes with altitudes when coming back into the class B VFR then sit back and watch the aircraft step down at each class B ring.

Using the 'banana' seems primitive now.

Don Jones 07-06-2019 06:49 PM

Quote:

Originally Posted by bmarvel (Post 1357465)
Don, this is astonishing! While I appreciate the very concise answer, why wasn't I told that when I reported this problem to Dynon last September -- 9 months ago? In the back and forth that ensued, nothing was said about Skyview being unable to support enroute VNAV. Just a week ago when I provided additional information to the company on what I was seeing, I received a diagram back showing the ARINC wiring and configuration settings and asked to reconfirm those. The implication is that at least one person there was unaware of the Skyview limitation you just revealed. While I understand the focus has been on certification work on the HDX, it is disheartening to see this communications lapse occur. I'm disappointed.

Bill,
I totally understand your frustration. I have a couple of new guys in tech support and getting them fully trained is a loooooooooong process. If there is ever any question, feel free to reach out to me directly. I don't man the phones much these days, but am available to talk any time.
Just so you know, not all resources are on certification. Our product development group is very busy working on new stuff and software updates for the SkyView line and there is some pretty exciting stuff coming.

I will add this discussion to my weekly meeting with the tech support group as a learning opportunity for them.

ChiefPilot 07-06-2019 07:21 PM

Quote:

Originally Posted by Walt (Post 1357577)
Also STARs are now loaded with the step downs as well.

When was the last time you got a "descend via" (or "climb via") clearance in your RV? Most such SIDS/STARS have speed restrictions that the RV simply cannot make; a number of them simply state "Turbojets only".


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