Does a Garmin GTX345 show mode C traffic?

[RobertE]

Sorry if this topic has been covered to death but I can't find anything definitive via the search function.  

What I've witnessed with my installation is what prompts the question.  I see a lot of traffic - more than could be explained by ADS-B only aircraft.  But sometimes I visually see aircraft that I gotta believe have mode c transponders.  So does my installation, in fact, show all mode c traffic within the 30 mile hockey puck?

Secondarily, garmin touts Target Trend but I don't get it on the 696 I use to display traffic (I've not bothered displaying it on my iPad).  Is the root of my problem the device I'm using to display traffic?

[lamont337]

What is your installed equipment? I would think a mode C only target would have to be rebroadcast by a ground station first to show up on your screen. This is indirect but may show up the same. 

[donkaye]

10 minutes ago, RobertE said:

Sorry if this topic has been covered to death but I can't find anything definitive via the search function.  

What I've witnessed with my installation is what prompts the question.  I see a lot of traffic - more than could be explained by ADS-B only aircraft.  But sometimes I visually see aircraft that I gotta believe have mode c transponders.  So does my installation, in fact, show all mode c traffic within the 30 mile hockey puck?

Secondarily, garmin touts Target Trend but I don't get it on the 696 I use to display traffic (I've not bothered displaying it on my iPad).  Is the root of my problem the device I'm using to display traffic?

Looking at the Compatibility diagram for the GTX 345 on the Garmin Website doesn't show the 696 as being compatible.  The 796 is.  I get TargetTrend on my 796.  However, with bluetooth you should be able to get traffic on the iPad with TargetTrend.

You see Mode C Targets via TIS-B, which is part of the ADS-B System.

 

[RobertE]

1 hour ago, donkaye said:

Looking at the Compatibility diagram for the GTX 345 on the Garmin Website doesn't show the 696 as being compatible.  The 796 is.  I get TargetTrend on my 796.  However, with bluetooth you should be able to get traffic on the iPad with TargetTrend.

You see Mode C Targets via TIS-B, which is part of the ADS-B System.

 

Oops.  I see I misstated the facts.  Correct, the 696 isn't supported by the GTX345, which is why I display traffic on the 430W, which is.  I don't get target trend on the 430W.

 

[donkaye]

50 minutes ago, RobertE said:

Oops.  I see I misstated the facts.  Correct, the 696 isn't supported by the GTX345, which is why I display traffic on the 430W, which is.  I don't get target trend on the 430W.

 

That's true.  The 430W/530W don't have the computational horsepower to support TargetTrend.  The 796, GTNs, and iPad do.

[carusoam]

Computer horsepower doubles every few years...  

- my nav computer was built in 1994...  KLN90B.

- its data memory no longer holds the entire country's database.

 

The country's database has been expanding as quickly as computers speed up.

 

Must be time to plan another two-decade update.

Best regards,

-a-

[Marauder]

Sorry if this topic has been covered to death but I can't find anything definitive via the search function.  

What I've witnessed with my installation is what prompts the question.  I see a lot of traffic - more than could be explained by ADS-B only aircraft.  But sometimes I visually see aircraft that I gotta believe have mode c transponders.  So does my installation, in fact, show all mode c traffic within the 30 mile hockey puck?

Secondarily, garmin touts Target Trend but I don't get it on the 696 I use to display traffic (I've not bothered displaying it on my iPad).  Is the root of my problem the device I'm using to display traffic?

There are 3 ways an ADS-B out system will receive traffic. ADS-B supports an air to air direct identification of 2 airplanes who are both ADS-B compliant. You won't need the ground ADS-B ground stations to see this traffic. It excludes any mode C planes.

You could also receive ADS-R if you had a single "out" band and can see the ground stations. The 345 is broadcasting on 1090. But it also has a dual "in" band for both 1090 and 978. You will see traffic directly whether it is broadcasting 1090 or 978.

The third way is the TIS-B. This is a broadcast from a ground station that would send up to your plane the traffic seen by a radar site. If you are flying in a radar coverage area, your ADS-B "out" triggers the ground stations to send up traffic seen by radar. This is where you would see the mode C. The limitation is if you are too low to see the ground stations. 

[RobertE]

Ahh, thanks Marauder.  That makes perfect sense.

[Cruiser]

14 hours ago, Marauder said:

The limitation is if you are too low to see the ground stations. 

Or the target is too low to be seen on the radar. This is the case at most non towered airports with planes in the pattern. While ADS-B offers a great improvement in traffic awareness, there is no single scenario in which it will identify all the traffic that might be present in your airspace. 

You still have to look out the window to "see and avoid"

Another problem that has not been sufficiently addressed is the location of traffic on your display. We operate in a dynamic environment, with both you and the traffic moving, display of the target may not be the actual location of the traffic when you look for it. Just like weather, there is a delay in information that you get in the cockpit. Be careful.

[Piloto]

The GTX 345 does not indicate Mode C or Mode S traffic directly from the traffic. To receive this traffic it needs a ground ADS-B UAT that would provide position information to this traffic. It can only show ADS-B out traffic directly from the plane. Outside the US it will not provide traffic info for Mode C/S traffic at all.

José 

[Piloto]

On ‎1‎/‎15‎/‎2017 at 1:38 PM, donkaye said:

That's true.  The 430W/530W don't have the computational horsepower to support TargetTrend.  The 796, GTNs, and iPad do.

As per this picture: https://buy.garmin.com/en-US/US/p/11tre9 the GNS 530W supports traffic trend vertically and horizontal. But traffic data has to be input via the RS-232 interface. The GNS 530W does not compute the trends it merely display the vertical trend and heading data of the traffic provided by the source.

José

 

[rahill]

On 1/15/2017 at 9:45 AM, RobertE said:

Oops.  I see I misstated the facts.  Correct, the 696 isn't supported by the GTX345, which is why I display traffic on the 430W, which is.  I don't get target trend on the 430W.

 

A little surprising that TargetTrend doesn't work on the 696 -- it does work on the Aera 510!

Rich

Edited January 17, 2017 by rahill

[donkaye]

36 minutes ago, Piloto said:

As per this picture: https://buy.garmin.com/en-US/US/p/11tre9 the GNS 530W supports traffic trend vertically and horizontal. But traffic data has to be input via the RS-232 interface. The GNS 530W does not compute the trends it merely display the vertical trend and heading data of the traffic provided by the source.

José

 

Yes, Absolute motion, but NOT Relative motion, a big, big difference.

[rahill]

29 minutes ago, Piloto said:

As per this picture: https://buy.garmin.com/en-US/US/p/11tre9 the GNS 530W supports traffic trend vertically and horizontal. But traffic data has to be input via the RS-232 interface. The GNS 530W does not compute the trends it merely display the vertical trend and heading data of the traffic provided by the source.

José

 

I don't think that image is showing TargetTrend, rather that's the standard traffic picture that the 430 and 530 provide with a GTX 345 or any other device that can feed it traffic data.  The 430 and 530 display the altitude difference, vertical trend (climbing or descending), and the velocity vector (relative to the ground) of the target.  The velocity vector (i.e., ground path) of a target is useful but doesn't really tell you which way the target is headed relative to you, since you're moving as well. TargetTrend (on the GTN units, Pilot, 796, etc.) displays the _relative_ velocity vector, which is a much more meaningful and helpful piece of data.  It's a simple calculation but apparently the vector math taking your velocity and the target velocity into account is a bit much for the older units.

Rich

[Marauder]

I don't think that image is showing TargetTrend, rather that's the standard traffic picture that the 430 and 530 provide with a GTX 345 or any other device that can feed it traffic data.  The 430 and 530 display the altitude difference, vertical trend (climbing or descending), and the velocity vector (relative to the ground) of the target.  The velocity vector (i.e., ground path) of a target is useful but doesn't really tell you which way the target is headed relative to you, since you're moving as well. TargetTrend (on the GTN units, Pilot, 796, etc.) displays the _relative_ velocity vector, which is a much more meaningful and helpful piece of data.  It's a simple calculation but apparently the vector math taking your velocity and the target velocity into account is a bit much for the older units.
Rich

I agree I think it is showing direction and rate of climb and descent. Here is a photo of an actual flight I made where target trend was adding a value to the evaluation of a threat or not. The red arrow is where the nose of the traffic is pointed. The blue arrow is my direction of flight. The green arrow I drew in is the actual target trend direction the plane is headed. Between his altitude difference 3,900 feet below me and his target trend direction, I was certain he would fly behind me, not where the red and blue arrow would suggest he would be.




Sent from my iPad using Tapatalk

[Piloto]

3 hours ago, rahill said:

I don't think that image is showing TargetTrend, rather that's the standard traffic picture that the 430 and 530 provide with a GTX 345 or any other device that can feed it traffic data.  The 430 and 530 display the altitude difference, vertical trend (climbing or descending), and the velocity vector (relative to the ground) of the target.  The velocity vector (i.e., ground path) of a target is useful but doesn't really tell you which way the target is headed relative to you, since you're moving as well. TargetTrend (on the GTN units, Pilot, 796, etc.) displays the _relative_ velocity vector, which is a much more meaningful and helpful piece of data.  It's a simple calculation but apparently the vector math taking your velocity and the target velocity into account is a bit much for the older units.

Rich

I think you are referring to relative ground tracks. But although the trend vectors is nice to watch is useless when you start a turn to avoid traffic. You could actually get into a collision path because there is no guidance on the turn radius. This is one of the issues were TCAS III concept failed http://www.ll.mit.edu/mission/aviation/publications/publication-files/atc-reports/Burgess_1995_ATC-231_WW-15318.pdf . That is why altitude deviation is used to avoid a collision (TCAS II). Even if you do not have the trend vector you can still see the traffic approximation like for an observation balloon.

José

Edited January 17, 2017 by Piloto

[thinwing]

I am continually amazed at the depth of knowledge on this forum...

[donkaye]

On 1/17/2017 at 11:27 AM, Piloto said:

I think you are referring to relative ground tracks. But although the trend vectors is nice to watch is useless when you start a turn to avoid traffic. You could actually get into a collision path because there is no guidance on the turn radius. This is one of the issues were TCAS III concept failed http://www.ll.mit.edu/mission/aviation/publications/publication-files/atc-reports/Burgess_1995_ATC-231_WW-15318.pdf . That is why altitude deviation is used to avoid a collision (TCAS II). Even if you do not have the trend vector you can still see the traffic approximation like for an observation balloon.

José

There is nothing like target trend.  I can have 30 targets on the screen, and if no trend line is crossing the ownship icon, I'm feeling pretty comfortable.  There is no comparison with the absolute vector.  I have easily seen targets out the window that I would never have seen.  The most interesting ones are the ones on a collision course but at a different altitude.  It is amazing to watch as they intercept the aircraft and pass overhead exactly at the collision point shown on the screen.  It's one of the most valuable additions to my upgrade.

[carusoam]

Can I sneak another detail in?

I was flying right seat as a safety pilot the other day...

The iPad was busy showing an IFR plate with the blue dot/airplane on the plate.

No other planes were appearing as traffic normally does on the WingX.

Do you guys get traffic when yo have the IAPs up?

We we're doing practice approaches, so it was VMC and VFR flights were allowed...

We only had one iPad out, my sole responsibility was watching for traffic.

I was hoping to find some planes and verify them on the plate.

It was probably too crummy for a lot of VFR pilots today...

Best regards,

-a-

[Marauder]

Can I sneak another detail in?

I was flying right seat as a safety pilot the other day...

The iPad was busy showing an IFR plate with the blue dot/airplane on the plate.

No other planes were appearing as traffic normally does on the WingX.

Do you guys get traffic when yo have the IAPs up?

We we're doing practice approaches, so it was VMC and VFR flights were allowed...

We only had one iPad out, my sole responsibility was watching for traffic.

I was hoping to find some planes and verify them on the plate.

It was probably too crummy for a lot of VFR pilots today...

Best regards,

-a-

I know if you have the plate up on GP, it does not display traffic on the plate. I don't fly with instrument chart overplayed on the map but I would think it should display traffic. I know it does show weather.

Sent from my iPad using Tapatalk

[Danb]

Chris it show weather on the plates in foreflight 

[Marauder]

Chris it show weather on the plates in foreflight 

Do you know if the plate is overlaid on the map traffic is shown on ForeFlight?


Sent from my iPad using Tapatalk

[Bob - S50]

A couple points.  We have a GTX345 and I use Garmin Pilot on an Android.

1.  The other day I was a safety pilot and on the way home there was converging slower traffic at about 10:30 and 1500' below us.  However, the target trend (green) vector showed him crossing directly below us.  The symbology  showed him climbing.  As we got closer, I suggested we turn left to pass behind him and it's a good thing we did.  Had we not altered course, we would have tried to defy physics by occupying the same airspace at the same time.  He never saw us.  Target trend is awesome!

2.  I almost always fly with Garmin Pilot in split screen.  On one half I display either a sectional or low chart with traffic displayed.  On the other half I usually show the traffic display but will switch it to either charts or weather depending on my needs.  I like the traffic display there most of the time because it is easier to pick out the traffic than it is over a sectional.  However, even when I'm displaying a chart I can still see traffic over the map.  And if I'm IFR, and might need an approach plate, I'm more likely to display a low chart than a sectional which makes it easier to see traffic.

[Danb]

Not sure Chris I can't check it until in the plane with the traffic enabled, I'll check later this week.

[Danb]

5 hours ago, Bob - S50 said:

A couple points.  We have a GTX345 and I use Garmin Pilot on an Android.

1.  The other day I was a safety pilot and on the way home there was converging slower traffic at about 10:30 and 1500' below us.  However, the target trend (green) vector showed him crossing directly below us.  The symbology  showed him climbing.  As we got closer, I suggested we turn left to pass behind him and it's a good thing we did.  Had we not altered course, we would have tried to defy physics by occupying the same airspace at the same time.  He never saw us.  Target trend is awesome!

2.  I almost always fly with Garmin Pilot in split screen.  On one half I display either a sectional or low chart with traffic displayed.  On the other half I usually show the traffic display but will switch it to either charts or weather depending on my needs.  I like the traffic display there most of the time because it is easier to pick out the traffic than it is over a sectional.  However, even when I'm displaying a chart I can still see traffic over the map.  And if I'm IFR, and might need an approach plate, I'm more likely to display a low chart than a sectional which makes it easier to see traffic.

Bob this Adsb traffic is working and more useful than I would have ever believed, real glad I had glad 345 installed.