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

[RobertE]

I just checked flightaware for the record of a recent flight and I noticed it had my track all the way to touchdown. This was at a coastal airport where I thought radar was unavailable below a couple thousand feet.  Does my mode s and ads-b mean that I’m tracked pretty much anywhere, regardless of radar coverage?

[RLCarter]

Big brother is watching

[gsengle]

Yep it even works *on* the ground at big airports. You don’t need the radar you just need to be in reception distance. Big benefit in mountainous terrain.


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[RobertE]

So does this mean I can call ATC well before I’m in classic radar coverage?  Stated differently, will I show up on the controller’s scope before the first radar pingg touches me?  

[RLCarter]

They can see you at your hangar or as soon as your ADS-B is powered up

[gsengle]

They can see you at your hangar or as soon as your ADS-B is powered up

You’re cute but not helpful.


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[gsengle]

So does this mean I can call ATC well before I’m in classic radar coverage?  Stated differently, will I show up on the controller’s scope before the first radar pingg touches me?  

Eventually yes.


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[kortopates]

What we see in the way of ADSB traffic and what ATC sees are two different things since ADSB is not fully implemented in the TRACONS and centers. They are still rolling it out. The busiest TRACON in the country that I sit under doesn’t even have a date on calendar yet. But I can see Adsb traffic on the ground easily via ADSb air to air transmissions.


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[81X]

3 hours ago, RobertE said:

I just checked flightaware for the record of a recent flight and I noticed it had my track all the way to touchdown. This was at a coastal airport where I thought radar was unavailable below a couple thousand feet.  Does my mode s and ads-b mean that I’m tracked pretty much anywhere, regardless of radar coverage?

Yes.  ADS-B in its purest form doesn't require radar.  Your position is derived from your GPS source (which you have on the ground) and then sent via data once you are able to communicate with one of the ads-b ground stations.  As others mentioned, this could be as low as on the ground and is also not fully rolled out, some of ATC still uses radar.

Edited September 1, 2018 by 81X

[PaulM]

ADSB is line of sight, transmitted by your transponder every second.   No radar involved. 

So, if you have ADSB in you will see ADSB traffic at your airport..   In flight the FAA will not have data on you until you are in line of sight range of an FAA ADSB ground antenna.  These can be at airports (usually Class B, C and some D's) and elsewhere.   Also the FAA towers usually pick up the ADSB signal lower than radar would normally identify you.   Currently this ADSB traffic is not used by the secondary radar controllers. 

In addition to this Flightaware, Flightradar 24 and others use private ADSB receivers all around the country to augment their ADSB data.  Seeing your flight to the ground means that someone in that area has an ADSB antenna and is relaying the data to Flightaware.   If you look at the track log it will tell you the source of the position data. 

Mode-s meant that radar sites could track you by ICAO ID when you were within their service volume.  ADSB means that you are actively transmitting your location at all times to everyone within line of sight. 

[Bob - S50]

And to piggyback on that, no they won't always see you all the way to the ground.  It all depends on the ground antenna location, terrain, distance, and your altitude.  As Paul said, line of sight.  Most of our flights disappear around 500' or so.  Probably about the time we fly below the ridge line that lies between our airport and the SEA airport.

[cliffy]

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. 

[Raptor05121]

Here in Florida I pick up towers at about 400' AGL

[bob865]

On ‎8‎/‎31‎/‎2018 at 8:33 PM, kortopates said:

What we see in the way of ADSB traffic and what ATC sees are two different things since ADSB is not fully implemented in the TRACONS and centers. They are still rolling it out. The busiest TRACON in the country that I sit under doesn’t even have a date on calendar yet.

Can confirm on the east coast too.  We had a ATC panel with Charlotte, NC controllers last weekend and they confirmed they do not see ADS-B yet and have no idea when they will.

[aviatoreb]

Isn't there some kind of ADSB relevant tracking service for airplanes on the ground?  I think I have seen airports on the ground on my ADSB in when flying over very large airports like ORD.

[jetdriven]

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

[jaylw314]

46 minutes 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.

I believe those are local systems for ground controllers, though, and not relayed to ATC.

[aviatoreb]

57 minutes 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.

Are those GPS based?  Anyway I was very curious to see that this data was broadcast and available for me to receive on my little ADSB receiver.  Fun to see while zipping right over ORD at 17k.

[kortopates]

10 minutes ago, aviatoreb said:

Are those GPS based?  Anyway I was very curious to see that this data was broadcast and available for me to receive on my little ADSB receiver.  Fun to see while zipping right over ORD at 17k.

What the tower controllers see are transponder based systems for ground control which have been in existence for years. Which is in part why a few years ago the AIM was updated to say to always leave your transponder on. (Smaller GA towers that do have a radar feed have the technology to filter ground data out.) But what you see in the air crossing within range are from air-to-air ABS/B Out broadcast - I don't believe ground packets are rebroadcast. 

[Mooneymite]

10 minutes ago, kortopates said:

What the tower controllers see are transponder based systems for ground control which have been in existence for years. Which is in part why a few years ago the AIM was updated to say to always leave your transponder on. (Smaller GA towers that do have a radar feed have the technology to filter ground data out.) But what you see in the air crossing within range are from air-to-air ABS/B Out broadcast - I don't believe ground packets are rebroadcast. 

ASDE:

Airport Surface Detection System — Model X (ASDE-X) is a surveillance system using radar, multilateration and satellite technology that allows air traffic controllers to track surface movement of aircraft and vehicles. It was developed to help reduce critical Category A and B runway incursions.

The ASDE-X alerts air traffic controllers of potential runway conflicts by providing detailed coverage of movement on runways and taxiways. By collecting data from a variety of sensors, ASDE-X is able to track non-transponder equipped and transponder equipped vehicles and aircraft on the airport movement area.

The data that ASDE-X uses comes from the following sources:

1. Surface surveillance radar located on top of the air traffic control tower and / or surface surveillance radar located on a remote tower
2. Multilateration sensors located around the airport
3. Airport Surveillance Radars such as the ASR-9
4. Automatic Dependent Surveillance — Broadcast (ADS-B) sensors
5. Terminal automation system to obtain flight plan data.

By fusing the data from these sources, ASDE-X is able to determine the position and identification of aircraft and vehicles on the airport movement area, as well as aircraft flying on final approach to the airport.

[Mooneymite]

ASDE was rendered unreliable at EWR because the airport is surrounded by multiple highways.  On those highways, truckers (wishing to remain un-tracked by their employers) utilized GPS blockers.  These GPS blockers made aircraft tracking unreliable.

https://www.dx.com/p/hakkadeal-jax-110d-2-car-gps-satellite-signal-cutoff-device-blocker-584264?tc=USD&ta=US&gclid=CjwKCAjw_b3cBRByEiwAdG8WqtlokJEaXvbPeH0OFsf1okCkaxVCfdtH4gr8nhw17kDWxN0g7t-ocRoCWvMQAvD_BwE#.W5BMR-hKiUk

[cliffy]

With the full roll out of ADSB at major airports ALL ground traffic (cars, buses, trucks, tugs, etc) inside the airport will be using ADSB equipment that the tower can follow on a screen. This is why we have the requirement for WAAS GPS motors on our ADSB in flight. The system was designed form the start to monitor ground traffic where they need the small EPE from WAAS for runway incursions. Read the enabling legislation. Its in there. Designed from the top down and we're at the bottom.  

Does anyone really think that we needed the difference between WAAS and non-WAAS accuracy in flight?  Non-WAAS is what? 100-200 feet EPE maybe at worst. 

[kortopates]

3 minutes ago, cliffy said:

Does anyone really think that we needed the difference between WAAS and non-WAAS accuracy in flight?  Non-WAAS is what? 100-200 feet EPE maybe at worst. 

I think the early on planned usage of WAAS  advantages wasn't so much for ground traffic as it was for providing VNAV. non-waas wasn't good enough to provide any form of VNAV. For awhile they (FAA and ICAO) even considered ground based augmentation GBAS  (among other methods) which could do the same thing but only locally. I am sure glad they wisely chose SBAS!

[cliffy]

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. 

Edited September 6, 2018 by cliffy

[kortopates]

6 minutes 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. 

Sorry, I get your point now. WAAS does provide an accuracy they didn't have on the ground and includes better coverage, but I would think they also did it for the better accuracy in altitude reporting. Even though the current mode C reporting is adequate, we can certainly expect they are looking for improved technology to reduce separation requirements both laterally and vertically in the way off future. Of course if they get too crazy they will also adopt rules like we have to be flying on autopilot with min performance criteria to support reduced separation etc.