Lovin' ADS-B

[Dave Piehler]

I did my first long XC trip this weekend after installing the GDL88 and Flightstream 210 (naturally Garmin introduced a new solution just as my install was being completed, but that's another topic).  I'm liking what I'm seeing.  Weather is quite usable, nicely integrated with Foreflight both graphically and in the lookups for the airports.  TIS-B traffic is fascinating, though, of course, incomplete.  I found it useful on a couple occasions to track traffic I was given by Center.  Bidirectional communication from the GNS-430W to the iPad for flight plans is marvelous. 

On the FIS-B side,I had to keep an eye on a line of showers associated with a stationary front today, and found the radar information more than adequate for strategic planning.  There's certainly more information available than there was with the basic XM Weather subscription.

One question I have I how long it takes an aircraft to register on TIS-B after it takes off.  I can envision passing an airport with departing traffic and potentially not seeing it on TIS-B due to system lag.  Does anyone know how long it takes for an aircraft to show up once it lifts off?

[donkaye]

24 minutes ago, Dave Piehler said:

I did my first long XC trip this weekend after installing the GDL88 and Flightstream 210 (naturally Garmin introduced a new solution just as my install was being completed, but that's another topic).  I'm liking what I'm seeing.  Weather is quite usable, nicely integrated with Foreflight both graphically and in the lookups for the airports.  TIS-B traffic is fascinating, though, of course, incomplete.  I found it useful on a couple occasions to track traffic I was given by Center.  Bidirectional communication from the GNS-430W to the iPad for flight plans is marvelous. 

On the FIS-B side,I had to keep an eye on a line of showers associated with a stationary front today, and found the radar information more than adequate for strategic planning.  There's certainly more information available than there was with the basic XM Weather subscription.

One question I have I how long it takes an aircraft to register on TIS-B after it takes off.  I can envision passing an airport with departing traffic and potentially not seeing it on TIS-B due to system lag.  Does anyone know how long it takes for an aircraft to show up once it lifts off?

Dave, several issues here.  First is that without Active traffic you may not receive any ADS-B (unless you have a GBT on your field) until you get high enough to receive the broadcasts, usually around 1,500 feet.  So I wouldn't count on it until everyone has ADS-B Out, which will be never.  Second, TIS-B is just regular radar returns from traffic that ATC sees that doesn't have ADS-B Out, so it will be much slower than the returns of the ADS-B traffic. Doesn't it take about 12 seconds per radar sweep?  Also, it is my understanding that while most GBTs have TIS-B capability, not all of them have it.

With regards to FIS-B weather as compared to XM weather, XM provides much more resolution over the whole country and many more products with the middle Aviator subscription than does FIS-B.  For me XM is worth the money, and if you have the GDL 69A that is the one time you don't have to pay for a second subscription, since the Flight Stream 210 transmits XM weather to the iPad.

[Dave Piehler]

Don,

When a plane takes off it must climb high enough to receive broadcasts.  Conversely, I assume it also doesn't show up as traffic until it's high enough to register.  Hence my question:  how long does it take a plane to show up as traffic after it takes off?  That lag could be significant.

[gsengle]

Remember that it's more complicated than that, it doesn't have to "register" at all with atc radar if you're both on the same band and equipped. Your ads-b gear can listen directly to the broadcast from the other plane....

Sent from my iPhone using Tapatalk

[Cruiser]

what is the refresh rate for TIS-B data? What about ADS-R updates?

If you are ADS-B OUT equipped and receiving a ground station what is the lag time for the traffic displayed on your screen?

[Raptor05121]

10 hours ago, Cruiser said:

what is the refresh rate for TIS-B data? What about ADS-R updates?

If you are ADS-B OUT equipped and receiving a ground station what is the lag time for the traffic displayed on your screen?

I'm -IN only, and on my tablet, ground station receive and traffic display is never more than 2 minutes old, usually a couple seconds.

[Piloto]

What ADS-B/UAT will not tell you is about that traffic landing at the opposite end of the runway you are taking off. I have faced this scenario twice at KPHK and TJMZ. Luckily my ATD-300 Traffic-Watch alerted me on time and I held up my departure. ADS-B/UAT or TIS is only good at altitude. In the traffic pattern is questionable and on the ground it does not work.

José

[DaV8or]

It seems to me that the only thing that makes sense is a hybrid of ADS-B broadcast and active traffic systems. I say this only because I assume and it is only an assumption, that ATC can see at least some of the NORDO traffic with their radar sweeps. You guys that know ATC feel free to correct me. Can you see a 1946 Luscomb with no electrical system and if you can, is this info relayed to the ADS-B network? 

[StevenL757]

On May 10, 2016 at 10:54 PM, Dave Piehler said:

Don,

When a plane takes off it must climb high enough to receive broadcasts.  Conversely, I assume it also doesn't show up as traffic until it's high enough to register.  Hence my question:  how long does it take a plane to show up as traffic after it takes off?  That lag could be significant.

Dave, your post possibly crossed with Don's reply...he mentions 1500 feet as a guideline altitude for that.

[Piloto]

14 hours ago, DaV8or said:

It seems to me that the only thing that makes sense is a hybrid of ADS-B broadcast and active traffic systems. I say this only because I assume and it is only an assumption, that ATC can see at least some of the NORDO traffic with their radar sweeps. You guys that know ATC feel free to correct me. Can you see a 1946 Luscomb with no electrical system and if you can, is this info relayed to the ADS-B network? 

Not all ATC radar sites have primary radars for non txpr traffic. Detection of non txpr traffic is more range and aircraft size limited than txpr equipped traffic. Weather in between is another factor that limits non txpr traffic detection range.

The fact that the onboard txpr reply light is blinking does not mean you are visible to ATC. It just mean that your transponder is replying to an ATC interrogation from a 2,000 watts ATC transmitter but your transponder 200 watts may not be strong enough to be received by the ATC radar due to distance or altitude.

José

[DaV8or]

8 hours ago, Piloto said:

Not all ATC radar sites have primary radars for non txpr traffic. Detection of non txpr traffic is more range and aircraft size limited than txpr equipped traffic. Weather in between is another factor that limits non txpr traffic detection range.

The fact that the onboard txpr reply light is blinking does not mean you are visible to ATC. It just mean that your transponder is replying to an ATC interrogation from a 2,000 watts ATC transmitter but your transponder 200 watts may not be strong enough to be received by the ATC radar due to distance or altitude.

José

No, I get that active onboard TAS is the best one can get, but I thought that having ADS-B augment it might be useful for catching at least some NORDO airplanes.

[flyboy0681]

On May 9, 2016 at 5:21 AM, donkaye said:

 

With regards to FIS-B weather as compared to XM weather, XM provides much more resolution over the whole country and many more products with the middle Aviator subscription than does FIS-B.  For me XM is worth the money, and if you have the GDL 69A that is the one time you don't have to pay for a second subscription, since the Flight Stream 210 transmits XM weather to the iPad.

Correct on the XM resolution. While flying I switch back and forth to compare and there is no comparison. ADS-B displays large color blocks while XM displays very fine pixels, making it much easier to decipher intensity levels. 

[Bob - S50]

On 5/11/2016 at 9:28 PM, DaV8or said:

It seems to me that the only thing that makes sense is a hybrid of ADS-B broadcast and active traffic systems. I say this only because I assume and it is only an assumption, that ATC can see at least some of the NORDO traffic with their radar sweeps. You guys that know ATC feel free to correct me. Can you see a 1946 Luscomb with no electrical system and if you can, is this info relayed to the ADS-B network? 

As a follow-on to what Jose said, doesn't an active traffic system require a mode S transponder?  If they have that, unless they are below radar coverage, won't ATC see them?  If ATC sees you and them, and you have ADS-B OUT/IN, won't you see them?

Just guessing since I don't really know anything about active traffic other than TCAS.

[StevenL757]

10 hours ago, Bob - S50 said:

As a follow-on to what Jose said, doesn't an active traffic system require a mode S transponder?  If they have that, unless they are below radar coverage, won't ATC see them?  If ATC sees you and them, and you have ADS-B OUT/IN, won't you see them?

Just guessing since I don't really know anything about active traffic other than TCAS.

- As a follow-on to what Jose said, doesn't an active traffic system require a mode S transponder?  To be picked up by an aircraft having an active traffic system, a target aircraft needs to have a minimum of an operational Mode-C transponder.  Neither a "target" or an "interrogator" aircraft needs ADS-B in or out equipment on-board to be picked up by an aircraft having a TAS/TCAS system.

- If they have that, unless they are below radar coverage, won't ATC see them?  If ATC sees you and them, and you have ADS-B OUT/IN, won't you see them?  If I'm reading the first question correctly, it wouldn't matter whether ATC sees the target aircraft or not...just so long as the TCAS-equipped aircraft can interrogate it.  ADS-B in/out equippage for either aircraft (assuming two aircraft in this scenario - both with Mode-C or higher transponders and one with TCAS) has no impact here one way or another.

Thoughts or other experiences, anyone?

[Deb]

We have an Avidyne TAS 605 active traffic system. It works by interrogating transponders and will receive target information from an aircraft with any transponder (note: non-mode C transponders won't be tracked by the host aircraft above 12,000 ft). If the target aircraft has an altitude encoder, its relative altitude will be displayed/annunciated; otherwise the target is displayed/annunciated without altitude information ("altitude unavailable"). This system is independent of ADS-B. 

The range of the system is variable, depending on the model. Our range is 13 miles and +/- 5,500 ft. 

There is also a ground mode: It senses when you are on the ground (typically during startup) and does not display/annunciate other traffic on the ground. It will display airborne traffic. So we would be alerted to landing traffic (as José was), but not to an aircraft taking off from another runway (or from the opposite end of the runway).

Here's a link to the Pilot's Operating Handbook for Avidyne's TAS 600 series: http://www.avidyne.com/files/downloads/600%2D00145%2D000%5F1%2Epdf.

[Bob - S50]

Thanks for the clarification.  My point was that unless you want a system that tells you what to do to avoid a potential collision (TCAS), I don't see much benefit to having both ADS-B OUT/IN and active traffic.  As far as I can tell, the only time you would benefit from having both is if you are out of radar coverage and the other aircraft has mode C or S but not ADS-B OUT.  Just more weight, complexity, and maintenance cost for minimal gain.  Especially after 1/1/20 when most (but certainly not all) aircraft will have ADS-B OUT.