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Does ads-b allow tracking all the way to the ground?


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19 hours ago, jetdriven said:

yes, major airports have a system that allows ATC to identify airplanes on the ground, even the sequence lined up for takeoff.

How does the system know the location of the airplanes on the ground?  Is it GPS based?  Do the tracked airplanes need a special system to participate when they are on the ground or is it basically the same ADSB- gps based concept and my ADSB equipped airplane would also be tracked if taxing around at ORD and the other large airports?

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How does the system know the location of the airplanes on the ground?  Is it GPS based?  Do the tracked airplanes need a special system to participate when they are on the ground or is it basically the same ADSB- gps based concept and my ADSB equipped airplane would also be tracked if taxing around at ORD and the other large airports?


My TAS system on the L-3 9000+ will show ground vehicles and airplanes. I believe it is based on a transponder output. The plane in this picture is shown as a brown target. He was on the taxiway as I was landing at my airport (a non-controlled field).

7151292c8993f318d4237c096743e568.jpg

If I was at a towered airport and they had ground vehicles in the system they would show up as brown vehicles.
29b984eb7c805e7e9e0e5cd02573bf53.png


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28 minutes ago, Marauder said:

My TAS system on the L-3 9000+ will show ground vehicles and airplanes. I believe it is based on a transponder output. The plane in this picture is shown as a brown target. He was on the taxiway as I was landing at my airport (a non-controlled field).

The ADSB signal (from the ES or UAT transponder) includes the flight/ground status and GPS location.   How this is determined is up to the transponder and the aircraft.   Planes with squat switches use that, others use airspeed switches.  If nothing else the GPS logic will attempt to decide.   

It is expected that in the future all vehicles on the airport surface (cars, trucks, tug's etc.) will use an ADSB transmitter for a complete picture of the ground environment.  The ADSB information also includes the length and width of the target, as well as the offset from he GPS antenna to the center of the box, so that automated collision warnings can be given.  

Mode S transponders also had a similar air/ground determination and wouldn't reply to mode A&C requests when on the ground.   

As for the current ADSE-X system, that was already mentioned that it uses a fusion of technologies to provide information.

https://www.faa.gov/air_traffic/technology/asde-x/

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22 minutes ago, PaulM said:

The ADSB signal (from the ES or UAT transponder) includes the flight/ground status and GPS location.   How this is determined is up to the transponder and the aircraft.   Planes with squat switches use that, others use airspeed switches.  If nothing else the GPS logic will attempt to decide.   

It is expected that in the future all vehicles on the airport surface (cars, trucks, tug's etc.) will use an ADSB transmitter for a complete picture of the ground environment.  The ADSB information also includes the length and width of the target, as well as the offset from he GPS antenna to the center of the box, so that automated collision warnings can be given.  

Mode S transponders also had a similar air/ground determination and wouldn't reply to mode A&C requests when on the ground.   

As for the current ADSE-X system, that was already mentioned that it uses a fusion of technologies to provide information.

https://www.faa.gov/air_traffic/technology/asde-x/

All that data is part of the "squit" in an extended squitter.  I think "squit" has to be one of my favorite words ever. :D

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16 hours ago, Bartman said:

If I take off on IFR clearance from my home field my track on FlightAware picks up immediately. If I take off from my home field without IFR clearance then FlightAware doesn’t pick me up until about 4,500 ft.

Can I ask what are your transponders and ADSB equipment? 

What I see on your last flight is ADSB from KILM... to only center at the end. 

I am going to guess that you only have a mode C transponder with UAT?... not a 1090ES system.

What happens is that Flightaware can't pick up your ADSB signal until 4500'... but Indy Center has mode C coverage down to  2000-3000ft.    

With only a mode C information flightaware doesn't know it is you if you squawk 1200.     

So, on a VFR flight, you aren't an individual until the UAT ADSB signal is picked up... everything from the ground to 4500 is "unknown, could be someone else"  and once above 4500 your individual ICAO ID is received.

On an IFR flight (or VFR flight following)  you are code XXXX all of the time, so center + flightaware can tell it is you as low as center radar goes.. (2000ft) 

With a mode S transponder you are always identified by radar with your ICAO code so there won't be a difference. 

If someone at your home airport were link into Flightaware's network a ADSB receiver, then you would get reporting all the way to the ground:

https://flightaware.com/adsb/

What I have found is interesting is that Flightaware won't correctly guess the source and destination airports unless they are KXXX (4 letter)  or there is a filed IFR flight plan.   
If I fly from 1N7 to  (47N)  It tells me I flew from near Mt Pocono, to near Somerville.   But If I fly (VFR 1200)  from 1N7 to 4B6 and had a backup IFR flight plan for that day, it correctly tags it as Blairstown to Ticonderoga Muni.    They finally fixed the ICAO XXXX problems.. 

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If I take off on IFR clearance from my home field my track on FlightAware picks up immediately. If I take off from my home field without IFR clearance then FlightAware doesn’t pick me up until about 4,500 ft.


Because you haven’t turned on the “position only flights” feature. You log in and change it in your settings and now you’ll see em all.


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Another interesting issue, is that if the controller mis-identifies someone else for VFR flight following in the data block, it will get tagged to your plane until it is corrected.

So flightaware says that I was down in Florida on Jul19th for about 10 mins..   

This is because the only link between a bare Mode C squawk and the N number is what the controller types in.  

When I first saw that flight I worried that someone had misconfigured their ICAO code... but saw it wasn't ADSB, only mode C. 

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1 hour ago, PaulM said:

Another interesting issue, is that if the controller mis-identifies someone else for VFR flight following in the data block, it will get tagged to your plane until it is corrected.

Yes.  I was surprised once when I checked my N# on Flightaware and saw a flight that I hadn't taken.

I guessed it was the revenge of the hangar elves.  :(

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1 hour ago, PaulM said:

Can I ask what are your transponders and ADSB equipment? 

What I see on your last flight is ADSB from KILM... to only center at the end. 

I am going to guess that you only have a mode C transponder with UAT?... not a 1090ES system.

What happens is that Flightaware can't pick up your ADSB signal until 4500'... but Indy Center has mode C coverage down to  2000-3000ft.    

With only a mode C information flightaware doesn't know it is you if you squawk 1200.     

So, on a VFR flight, you aren't an individual until the UAT ADSB signal is picked up... everything from the ground to 4500 is "unknown, could be someone else"  and once above 4500 your individual ICAO ID is received.

On an IFR flight (or VFR flight following)  you are code XXXX all of the time, so center + flightaware can tell it is you as low as center radar goes.. (2000ft) 

With a mode S transponder you are always identified by radar with your ICAO code so there won't be a difference. 

If someone at your home airport were link into Flightaware's network a ADSB receiver, then you would get reporting all the way to the ground:

https://flightaware.com/adsb/

What I have found is interesting is that Flightaware won't correctly guess the source and destination airports unless they are KXXX (4 letter)  or there is a filed IFR flight plan.   
If I fly from 1N7 to  (47N)  It tells me I flew from near Mt Pocono, to near Somerville.   But If I fly (VFR 1200)  from 1N7 to 4B6 and had a backup IFR flight plan for that day, it correctly tags it as Blairstown to Ticonderoga Muni.    They finally fixed the ICAO XXXX problems.. 

I have an Avidyne AXP 322 remote mounted Mode S transponder with 1090 ADS-b out in good working order

I set FlightAware to show position only flights a long time ago, and I just re-confirmed it before writing this post.

It's not just me, and I see the same with others in my area and I know they have Mode S transponders as well.  I flew with a friend doing practice approaches up to 4,500 just last week but it does not show on FlightAware.  I'm sure its just due to the location and if I take off at a class C or B airport then I'm picked up immediately and will follow to the destination if I do not cancel IFR.  If I cancel IFR 10 miles out, then my track disappears. If just VFR and squawking 1200 then it does not pick up until above about 4500 and disappears about the same altitude as seen on my flight from 7/9/18 on FlightAware.  If we keep IFR to the ground like my last flight from ILM then FlightAware displays me to the ground.  

Adding a ground based receiver to enhance the network for FlightAware sounds interesting...

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13 minutes ago, Bartman said:

It's not just me, and I see the same with others in my area and I know they have Mode S transponders as well.  I flew with a friend doing practice approaches up to 4,500 just last week but it does not show on FlightAware.  I'm sure its just due to the location and if I take off at a class C or B airport then I'm picked up immediately and will follow to the destination if I do not cancel IFR.  If I cancel IFR 10 miles out, then my track disappears. If just VFR and squawking 1200 then it does not pick up until above about 4500 and disappears about the same altitude as seen on my flight from 7/9/18 on FlightAware.  If we keep IFR to the ground like my last flight from ILM then FlightAware displays me to the ground.  

Yes, it looks like there is a private receiver somewhere picking you up when you're high but nothing near your home airport so down low you're at the mercy of the FAA. Not sure if you can see it on the free account, but if you view a flight and click "View Track Log" you can see the source for each data point.

 

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2 hours ago, gsengle said:

 


Because you haven’t turned on the “position only flights” feature. You log in and change it in your settings and now you’ll see em all.


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No that's not the case here.  I've had the position only flights on for a long time, and confirmed the setting today.  Like Paul stated my last flight was followed by FlightAware ADS-b for most of the flight, but the last few readings were from Indy Center only, but still followed basically to about 400ft.

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1 hour ago, Bartman said:

I have an Avidyne AXP 322 remote mounted Mode S transponder with 1090 ADS-b out in good working order

 

It's not just me, and I see the same with others in my area and I know they have Mode S transponders as well.

Then the answer is that Indy center either is mode C only.... or somehow their data link to FAA central isn't including the Mode S - ICAO code in the feed to the FAA.    As you indicate it isn't your equipment... the common item is the ground radar site. 

The behavior is classic Mode C 1200 only + ADSB...  to have foreflight tag your  target you need either a individual squawk, or you need your ICAO code to be attached to the return via mode S or ADSB. 

Given the lack of flightaware ADSB coverage in your area you would probably qualify for their free ADSB ground station.. if you have power/internet in a place on the field.. 

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22 hours ago, cliffy said:

The implementation of  WAAS is a separate issue from the requirement to use WAAS for ADSB.  Chicken before the egg.

The "requirement" to inculcate WAAS into the ADSB system was for its accuracy for ground based traffic at large airports. Something the FAA won't even discuss as I tried at OSH this year.  

The use of WAAS for approaches is an entirely different issue. 

I think another thing that WAAS provides is additional integrity checking that isn't available with GPS by itself.

This indicates that WAAS is not required for ADS-B, but gives no detail (see the last question):

https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/faq/waas/   

 

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On 9/5/2018 at 7:36 AM, cliffy said:

The FAA has a website where you zoom in to any area and see at what altitude you will be seen by ADSB coverage. Had it shown to me at OSH this year but I didn't copy the URL for it. Its dynamic also so you can see what areas are covered at different altitudes above any particular airport. Where I live I have to be more than 3000' AGL to be picked up. 

I think I found it with a little help from Google.

https://www.faa.gov/nextgen/programs/adsb/ICM/

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