Cns/atm / Ads-b

[beerdrinker]

AS I understand it both CNS/ATM and ADS-B provides Air Traffic Control with a pseudo radar picture on a computer screen of the position of aircraft based on the GPS/INS position transmitted by aircraft.

What then is the difference between CNS/ATM and ADS-B?

[LeadSled]

Beerdrinker.
CNS/ATM is the acronym for "Communication and Navigation Services/Air Traffic Management", it applied to the service providers, not equipment.
ADS-B/C etc is, in reality, just a datalink, what the data is, and what you do with it, on the ground or in the air, determines what use you get out of it.
ICAO recognise three quite separate and mutually incompatible ADS-B/C systems, UAT(CDMA format), VDL-4 (TDMA format) and ES1090, which uses some previously unavailed but very bandwidth limited message slots on the Mode S transponder signal format.
Tootle pip!!

[slamer.]

Automatic Dependant Surveilance-Broadcast (ADS-B)

ADS-B data is sourced from the aircraft mode S transponder or Universal Access Tranceiver (GA aircraft) and is totally independendent from CPDLC & ADS-C (contract) activity. It broadcasts continuously (about twice/sec) data such as Identification/Accuracy of GPS data/altitude/Vert trk/ Lat trk & GS and other info which ground stations and other aircraft can use.

In Aust a network of some 28 ground stations can receive ADS-B transmissions within approx 250nm (500nm around each station) to supplement radar coverage, together covering nearly all of Aust at 30000', this allows lat seperation of 5nm between ADS-B equip aircraft

[skiesfull]

C = Communications
1/. CPDLC - controller/pilot data link communications
2/. Airline operational control via datalink
N = Navigation
1/.Integrated GPS(GNSS) + time reference (updates FMC position)
2/. RNP (required navigation performance) for reduced lateral separation
S = Surveillance
1/. ADS -C
2/. RTA (required time of arrival)
ATM = Air Traffic Management

CNS-ATM is also known as FANS 1/A (Future Air Navigation Systems 1(for Boeing equipment and A for Airbus equipment)
FANS 2/B will be with us soon.
ADS-B (Automatic Depedendent Surveillance - Broadcast) will soon be used in USA, Australia and possibly Indonesia. It is different from CNS ATM in that it is to be used in remote areas, using ground relay stations and will reduce the lateral separation between aircraft from 10 mins (approx 70-80 nms) to 5 nms (using fixed Mach technique). It obviously has great potential for the Indian sub-continent, S.E. Asia and Africa.
All the above require sophisticated aircraft equipment, as well as ATC service. The Aussies have a good write-up on ADS-B, sorry haven't got the website, but try Googling.

[bookworm]

ADS-B/C etc is, in reality, just a datalink, what the data is, and what you do with it, on the ground or in the air, determines what use you get out of it.

I think that might be a bit misleading. The datalinks are UAT, VDL Mode 4 and 1090ES. ADS-B is a specific application of one of those datalinks to allow aircraft to broadcast their own position, and receive the positions of others.

UAT is intended to support other applications, for example weather transmission. 1090ES supports enhanced SSR by sending aircraft parameters in response to Mode S interrogation. Both of those are uses of the datalink but neither is ADS-B.

[Bigmosquito]

Some news from Europe on that subject.

CNS/ATM (Communication Navigation Surveillance/ Air Traffic Management), the ICAO preferred term.

Communication = CPDLC
Navigation = GNSS
Surveillance = ADS-B and ADS-C

ADS-B OUT = ADS-B transmitting
ADS-B IN = ADS-B receiving

FANS (Future Air Navigation Systems) was a manufacturer term from Boeing and Airbus. FANS 1 was for Boeing and FANS A for Airbus. FANS 1/A is a mixture of both. FANS 2, B or 2/B is the next generation.
FANS 1/A will still be used in remote areas such as over oceans and FANS 2/B will be used in more dense areas such as continental areas.
But as technologies evolved, obviously FANS 1/A will be replaced gradually I guess by FANS 2/B.

ADS-B is under the CASCADE program in Europe and it is not foreseen before 2015 (ADS-B OUT). You can find more information for Europe on the following website: http://www.eurocontrol.int/cascade.

Already discussed were the different technologies used. UAT, VDLM-4 and Mode S ES (1090ES). Mode S ES is just another evolution of the existing Mode S and is I guess the cheapest to install as it uses the same antenna as the DME if I am not mistaken. VDLM-4 will need another antenna and am not sure it will not interfere with VDLM-2, causing another concern... Might be wrong here...

Europe is considering the Mode S ES and VDLM-4 as it is ATN (Aeronautical Telecommunication Network) compatible. UAT is under study and could be considered for small GA aircrafts, eventhough there is a big discussion of extending the UAT to all operators. VDLM-4 is used in Sweden if I am not mistaken and it's a big question mark. Will it survive the market compare to the two other technologies?

The issue is that Europe is extending its ATN ground network for its own Link 2000+ program (CPDLC). They foresee a mandate date around 2015 above FL285. A foreward fit for new aircrafts by 2011 and retrofit by 2013. Some exceptions may apply.

Thus, causing some concerns about FANS 1/A already equipped aircrafts as they are not ATN equipped. The use of VDLM-2 may help to use the ATN network but not at its full capacity, the way I understand. Raising some questions about mixing ATN and FANS 1/A equipped aircrafts above FL285.

A very interesting subject and am sure that we are not finished to discuss about it.

Note:
One concern about the ADS-B OUT is that any persons may buy a 1090 receiver with the appropriate software and receive any information sent by the airplane within its antenna range on its laptop, exactly the same way a controller would receive the information. Something to think about as we do not necessary live in a friendly world... A rock sent to the legislators.

Bigmosquito.

[fm013]

VDL4 as an ADS-B datalink will not be used widely in Europe other than in certain regions like Sweden and Russia.

The main thing about ADS-B is what you can do with it. The US is already putting in a network of ground stations so they can eventually get rid of secondary radars. Europe will likely follow but plans here don't seem to be as firm.

A huge benefit will be airborne applications using ADS-B (a.k.a. ASAS). Again the US is leading here, e.g. UPS at Louisville.

[Bigmosquito]

Yes, that's why I wonder about the future of VDLM-4...

The big question about getting rid of secondary surveillance radar... The issue is which back-up the industry will decide to adopt?

BM.

[Swedish Steve]

One concern about the ADS-B OUT is that any persons may buy a 1090 receiver with the appropriate software and receive any information sent by the airplane within its antenna range on its laptop,

Some already do. Here is ADS-B pseudo radar plot of Sweden.

Flygradar LIVE - Se var flygplan befinner sig över Sverige (http://www.flygbilligt.com/radar/)

Note not all aircraft have ADS transmissions, but about 95pc of airliners in Swedish airspace do.