VFR Vertical Navigation - GPS Source?

[sunfish]

I note that the latest edition of the SKyview installation manual shows the various capabilities of the system depending on what type of GPS is installed.

TSO'd GPS shows the ability to to VNAV stuff.

The SV GPS doesn't.

Then there is the column NMEA GPS - presumably third party stuff and the comment that "some models" provide information for VFR vertical navigation.

Which models would that be or what is the required NMEA GPS output sentence?

Thank you in advance. I ordered my Skyview system last week.

 

[Dynon]

Without wading too deep into the techncials, here's the short list:

If you have a GTN or GNS 430W/530W, you get vertical guidance on the GPS side when you're on a GPS approach that provides vertical guidance (LPV, LNAV+V), and on the radio side when you're on a glideslope. This data comes across via ARINC.

If you have a Garmin SL30 or the new radios, you get glideslope information via Garmin's proprietary serial format.

If you have a Garmin portable x96 GPS, there is a proprietary Garmin sentence (not NMEA technically) that outputs the handheld's vertical nav feature as a glideslope.

Any of those will show up as a glide slope on the SkyView HSI, and, as of 6.0, can be flown by the autopilot in VNAV mode.

 

[jakej]

DS & others - WE do not have any GPSV approaches here in Australia & probably won't have for a few years (from the info I have) given that we don't have WAAS capability which would require geo stationary gps satellites at least.

Jake J

 

[hstaton]

Since I really dislike being forced into an obscenely over-priced Garmin solution, what are the chances of your GPS receiver ever having this capability?

 

[Juvat]

Hi Dynon Support:

What about enroute VNAV? Is this available as well? And if so, which GPS units are capable of it? I'm hoping there will be enroute VNAV too, and not just terminal VNAV for instrument approaches.

 

[dynonsupport]

We will follow a GS/GP needle whenever it exists, we don't care when and why it's there. However enroute vertical guidance is not a feature most GA GPS units have, it's more of an advanced FMS feature. I'll defer to the crowd here to tell you which ones do. You can always just use the altitude bug on the autopilot

We are interested what you might want out of "enroute VNAV" from a flight planning perspective. When you ask for this, what kind of planning are you hoping for? How would you expect to define altitudes and climbs/descents as they relate to your flight plan? This is something we've been considering here so your input would be appreciated. You should be aware that it would not be IFR legal, just for VFR use, because:

We don't have any plans to certify the SkyView system, which is what would be required for it to be a legal enroute or approach IFR navigator (at least in the USA, and most other countries are more strict, not less). You need to certify not just the GPS receiver hardware, but the navigator as a whole, which means all the software in the whole system down to databases. There is unfortunately a reason IFR GPS units cost so much, and it's defined in 800+ page TSO requirement documents.

 

[DonFromTX]

We all are needing something different I guess, but for me all I want is the capability for the non-pilot wife to arrive at the end of a nearby runway someplace, with minimal complications..

 

[Juvat]

Sorry, I should have been more specific. What I meant to say was it would be very good for the autopilot to be able to fly the vertical portion of RNP terminal departure and arrival procedures.

But I see from your post above that this is indeed possible since the Skyview autopilot will follow anything with a needle. I'm pretty sure that my Garmin GTN-650 will show a glidepath deviation needle (sent via ARINC to Skyview) for RNP arrivals and departures (the old "SIDs" and "STARs") so we should be good to go here.

As for enroute VNAV, you're exactly right. Just cranking the ALT knob is the way to go.

 

[preid]

For enroute VNAV, I gather it's fpm needed from a distance to the airport (aka- 20 miles from SEA at 9500msl, -XXXfpm descent to reach the airport) I've lived with thinking it out, but to Dons point, something simple a non pilot wife could look at and know how fast to descend.One could engage the AP and manually adjust that fpm if the AP doesnt do it.

 

[Bruno]

Reidvator

        ''For enroute VNAV, I gather it's fpm needed from a distance to the airport (aka- 20 miles from SEA at 9500msl, -XXXfpm descent to reach the airport)''
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Just about every handheld GPS will do that. I know the Avmap IV and the G295 will do it..

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''something simple a non pilot wife could look at and know how fast to descend''

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A call to ATC will solve that problem, they will even include turns if require  ;-)

Support

''We don't have any plans to certify the SkyView system''

What exactly do you mean by that...??  Will the Skyview ever be able to display an approach plate and a flight plan on the map like GRT, Garmin and AFS are doing now ??

Thanks

Bruno

 

[dynonsupport]

Displaying a picture of plate does not make you an IFR certified navigator. An IFR certified navigator is one that you tell to fly the RNAV 29R Y approach into KABC and it gives you a CDI and glideslope and lets you fly down to just a couple hundred feet above the airport using it as your only navigation source, and it does it using completely certified code and hardware that has an actual TSO. This is not something Dynon or any experimental EFIS can do.

Displaying plates is a capability SkyView will have in the future, but just like everyone else, this is just an image, not "guidance" where the computer tells you what to do based on your situation and position.

 

[mmarmol]

In response to the Dynon Support question of what we are looking for in a VNAV solution my idea is kind of the following:

My guidance comes from the way the big iron guys do it. You input a cruising altitude into your flight plan. Once you take off and engage VNAV autopilot the aircraft will climb, at an airspeed set by the pilot, up to the cruising altitude. For the descent you can have a "nominal descent rate" built into the Skyview (pilot puts it into the setup) that will prompt a "top of descent" for you to be at pattern altitude when you hit the airport. If you have an IFR navigator you can use the guidance from that box on the RNAV arrival and the approach.
If you don't want to use VNAV you can just fly the vertical portion of the flight plan by turning the altitude bug.

What are soem thoughts that people have?

 

[dynonsupport]

The new AP will already climb at a VS or IAS to a pre-selected altitude. So I don't quite get why you want this as part of the flight plan where it's harder to edit than just twisting the ALT, VS, or IAS knobs (or pressing our new Nose UP/DN buttons). So do people really want to plan their climb in the flight planning menu? What about enroute changes?

The descent stuff makes perfect sense and I think we're all on the same page there.

 

[keithpaterson]

For me, the ideal solution would be simple:

Allow for a barometric altitude (optional) to be inserted in the FLIGHT PLAN page by designing another column to the right of "ETE". If this was left blank, no VNAV indicator would display. If the aircraft was flying in GPS NAV between waypoints where there were altitudes inserted in both, a path can be built. Or, if there is only an altitude inserted for the next waypoint, using the default/selected vertical speed data, a useful VNAV indicator could indicate wheter you need to increase or reduce your vertical speed.

I would really find that feature handy.

Any comments?

 

[mmarmol]

Dynon Support,
I see the point in that it's an extra hassle to put in altitudes in the flight plan page to enable VNAV climbs.
The question then becomes, how can you have Skyview tell you when to start your descent? I suppose it knows where the flight plan ends and your current altitude so it can calculate a "Top of Descent" based on a pre-set descent rate/airspeed to get you to pattern altitude when you hit the end of the flight plan. This would be good for both the VFR and IFR crowd.
Personally, I think the option to be able to input your desired altitude in the flight plan, either directly on the waypoints or throughout the plan would be a great feature for the IFR crowd. This would allow us to do things like MCA's and MEA's but I understand the limited appeal. Something similar to what zukamkeith is suggesting would work.
Thoughts?

 

[keithpaterson]

Would such a feature be technically that difficult, in the context of the limited appeal? Although I think the appeal will be there for folk who are using the new "expert" autopilot option. So the "expert" facility would be that much enhanced...

Some comment from Dynon Support?

 

[jc2da]

I would want this ability. The tricky part is designing an interface to be easily usable and as intuitive as possible - holy grail stuff i know. However, i'm sure copying Garmin or how someone else has already done it for years would probably be a good start.

As a VFR pilot, i like to get on the AP as soon as possible. This is usually after i depart the pattern and am climbing. This lets me worry less about busting class B airspace while still talking to controllers and keeping my head on a swivel watching for traffic.

I am a BIG proponent on minimizing button pushes that keeps my eyes on the panel instead of looking outside for traffic. I wish Dynon would pay better attention to this issue.

 

[purlee]

Without wading too deep into the techncials, here's the short list:

If you have a GTN or GNS 430W/530W, you get vertical guidance on the GPS side when you're on a GPS approach that provides vertical guidance (LPV, LNAV+V), and on the radio side when you're on a glideslope. This data comes across via ARINC.

If you have a Garmin SL30 or the new radios, you get glideslope information via Garmin's proprietary serial format.

If you have a Garmin portable x96 GPS, there is a proprietary Garmin sentence (not NMEA technically) that outputs the handheld's vertical nav feature as a glideslope.

Any of those will show up as a glide slope on the SkyView HSI, and, as of 6.0, can be flown by the autopilot in VNAV mode.

This is true, however, having just read the GTN750 Flight Manual I notice that coupling this instrument for GPS based vertical guidance is unapproved,

2.11 Autopilot Coupling
IFR installations of a GTN allow the pilot to fly all phases of flight based on the navigation information presented to the pilot; however, not all modes may be coupled to the autopilot. All autopilots may be coupled in Oceanic (OCN), Enroute (ENR), and Terminal (TERM) modes.

This installation is limited to:

• Lateral coupling only for GPS approaches. Coupling to the vertical path for GPS approaches is not authorized.


Or am I reading this wrong. Seems like you can only vertically couple in VOR/LOC/ILS modes

 

[dynonsupport]

The document in question is here:
http://static.garmincdn.com/pumac/190-01007-A4_03.docx

That phrase is found in the "SAMPLE FLIGHT MANUAL SUPPLEMENT" for the GTN 750, which non-STC'd installs must have on board when flying. This is not the "flight manual". It is a template to create the appropriate one for your plane. You're supposed to edit it to the right limitations and carry it on board at all times.

It says something important in the opening notes:

3. These instructions are for reference only and should not be included as part of the flight manual supplement. The text that must be checked or edited for every installation is shown in RED; other changes may be required based on your particular installation.

And the section is:

2.11 Autopilot Coupling
The flight crew may fly all phases of flight based on the navigation information presented to the flight crew; however, not all modes may be coupled to the autopilot. All autopilots may be coupled in Oceanic (OCN), Enroute (ENR), and Terminal (TERM) modes.

This installation is limited to:

• Lateral coupling only for GPS approaches. Coupling to the vertical path for GPS approaches is not authorized.

Thus, the red section is something that MIGHT be needed in a flight manual for that specific install. Not all autopilots can properly couple to a GPS approach, so that may need to be restricted based on the autopilot that is installed. The Dynon SkyView AP was designed to fly a GPS approach however, and thus is approved.

At least that's our non-expert opinion. You might want to call Garmin and see if they agree. It's their document after all. Their competing experimental EFIS couples to the 750 as well so they don't have an issue with following a GPS approach with an AP.