ADS-B for GA in Europe?

[peterh337]

Don't worry - I think that poster is a bit of a troll.

What is needed to get a standard GTX330 to emit continuous ADS-B?

I think that if one connects NMEA data to one of its RS232 inputs, it will just radiate the lot, including (usefully) your GPS position. There is no configuration (in the firmware I have, dated c. 2005) for excluding any specific labels. I believe that came in a later revision, to enable the use of GPS ground speed for automatic GND/AIR switching without radiating anything. Wigglyamp will know for sure.

[ATCast]

Therefor it is undesirable that GA is equipped with uncertified ADS-B transponders.

I am confused by that! In Europe we are using Mode S transponders with extended squitter to emit ADS-B out. I think all the transponders available are certified?

Sorry to cause confusion. You are correct that the transponder is certified. The certification usually covers Mode S, as described in (E)TSO-C112.
However in general it does not cover the ADS-B specifications (E)TSO-C166b.

Some Mode S certified transponders radiate extended squitters, but are not ADS-B certified. Potentially they could send out corrupt ADS-B data, and in a few cases they do so.

In addition to corruption of data by the tranponder, the attached systems can cause problems. For example the time between the validity of the GPS position and the moment that it is send out by the transponder is too long in some systems.

At the moment all those issues are not really a problem since ADS-B is not used operationally within Europe. But to start operational use of ADS-B these problems need to be addressed.

ATCast

[Contacttower]

The only thing I'd be interested in is whether or not there is a possibility of getting weather etc through the system...are we likely to see that in Europe any time soon? Isn't the FAA planning to provide this for free to aircraft with the right equipment to receive it?

I have to admit I'm a bit behind with the details of this since it hasn't really received much coverage in the UK pilot community.

[peterh337]

For example the time between the validity of the GPS position and the moment that it is send out by the transponder is too long in some systems.

Can you supply more detals?

[betterfromabove]

Glad to see it's not just me that's been wondering about this technology and why once again there seems such a chasm between the US GA experience and the European one.

Thanks for all the informed and detailed responses - sure is valuable to not just me in understanding the question better.

One aspect only one post has touched on I think is the issue of fittability within the light GA fleet?

Notwithstanding the degree and richness of data being transmitted, what % of the GA fleet (in the widest sense...) might we expect to see able to fit this kit in 10 years time in the US.....and then in Europe?

Are there any devices out there viable for the fleet that currently is unable/unwilling to install Mode C? Or will ££/size/weight issues come into play in same way?

Thanks again,
BFA

[ATCast]

Peter, the concept of primary navigation does exist, and it is as you say not expressed in the form of equipment used, but of equipment carried. EASA probably thinks that if they make you carry a fallback system you will use it when you need it, even when they have not explicitly told you to do so.

I've looked up the AMC for B-RNAV, here is a section on GPS:

4.4.2.3 GPS
The use of GPS to perform Basic RNAV operations is limited to equipment approved to ETSO-C129a,
ETSO-C 145, or ETSO-C 146 and which include the minimum system functions specified in paragraph
4.2.1. Integrity should be provided by Receiver Autonomous Integrity Monitoring (RAIM) or an
equivalent means within a multi-sensor navigation system. The equipment should be approved in
accordance with the AMC 20-5. In addition, GPS stand-alone equipment should include the following
functions:
(a) Pseudorange step detection
(b) Health word checking.
These two additional functions are required to be implemented in accordance with ETSO-C129a
criteria.
Traditional navigation equipment (e.g. VOR, DME and ADF) will need to be installed and be
serviceable, so as to provide an alternative means of navigation.

That last sentence is there to make sure GPS is not the sole means of navigation, but the primary means. If you google "primary sole means navigation GPS" you will find more.

For a brief moment I thought you worked for Eurocontrol

you are not an IFR pilot

you are an instructor,

an FTO ground school teacher, perhaps?

You must be a PPL instructor

I think that poster is a bit of a troll.

You seem to think quite a lot of me.
I am not a pilot myself, but I am involved in standardisation of ATM-technologies. The reason that I join the discussion here is to better understand GA point of view.

ATCast

[ATCast]

Quote:
For example the time between the validity of the GPS position and the moment that it is send out by the transponder is too long in some systems.
Can you supply more detals?

If memory serves me right, the maximum latency time is 1.5 seconds for ADS-B installations certified for ADS-B-NRA (NRA = Non Radar Airspace, so ADS-B as sole means of surveillance). That is what is currently used over Hudson Bay in Canada for example.
That means that if the aircraft is flying at 500 Kts ground speed, the reported ADS-B position can be maximally 385 meter behind him.

For the European ADS-B mandate (so not targeting GA) the maximum latency is 0.6 seconds. For the aircraft flying at 500 Kts, the reported ADS-B position can be maximally 155 meter behind him.

Since GA are flying slower, I think that GA could do with less stringent latency requirements.

In both cases it is allowed for the transponder to compensate for some latency by extrapoling the GPS position using the GPS ground speed vector. There are limits to the amount of compensation allowed.

[ATCast]

The only thing I'd be interested in is whether or not there is a possibility of getting weather etc through the system...are we likely to see that in Europe any time soon? Isn't the FAA planning to provide this for free to aircraft with the right equipment to receive it?

From what I have understood there are no plans in Europe to provide weather. ADS-B on 1090 Mhz in not suitable to do that.

In the US they are deploying two separate systems, 1090Mhz for the big guys above 18000ft and UAT for the others. With UAT it is possible to upload weather.

[betterfromabove]

Worth adding with regard to Eurocontrol that their Airspace Infringement Initiative's report on FIS, which contains many solid suggestions, makes no explicit mention of ADS-B in its recommendations.

From what I can see, it assumes Mode S uptake will be limited in the European GA community (mainly Netherlands and Germany for country-specific reasons) and that full ADS-B will be prohibitively expensive or impossible for much of the c.120,000 GA fleet.

[achimha]

Under the existing EASA approvals for installing a Mode-S transponder providing elementary surveillance data, it is not permitted to radiate additional data elements such as position.

I keep reading this but have not managed to find any clear, official, binding statements.

My setup is a Filser/Funkwerk TRT800A transponder connected to an IFR certified GNS430W, configured to radiate extended squitter position data. The transponder comes with an EASA STC and its installation manual shows how to connect it to a GPS source and how to enable the extended squitter.

Installed and operated according to the STC. How could this be wrong? That's what the manufacturer says as well.

[peterh337]

I keep reading this but have not managed to find any clear, official, binding statements.

I wrote this up in 2008 - may be a start for research.

There is NO evidence that anybody actually cares what you radiate, and of course any planes visiting the EU, with Mode-S, will prob99 be radiating the whole lot anyway

I am not a pilot myself, but I am involved in standardisation of ATM-technologies. The reason that I join the discussion here is to better understand GA point of view.

That seems a good idea. It's a pity however that people involved in this are not IFR pilots. It's no wonder we get so many stupid regs. What exactly is the point in worrying whether position data is 0.6 seconds old? Radar does a sweep only about every 5-10 seconds...

I am sure the PRNAV utter-bollox (forcing 5-figure avionics upgrades) comes from the same stable. Currently, 99% of GA is unaware this bombshell is coming to UK enroute airspace.

[gasax]

Like many of these technical discussions on here I find this immensely depressing. I have a permit aircraft and one of the few 'advantages' I could see in fitting a Mode S transponder is that I could radiate a GPS position and so gain some limited 'protection' form that.

And yet we see people involved in the formulation of policy and process arguing about issues like data latency and quoting speeds of 500kts - what about the speed restrictions below 10,000? - (apart from the military naturally!). At 500kts you are dependent upon ATC radar predicting it course and where the aircraft is going - not about where it might or might not happen to be at any precise instant (let alone Peter's comment about radar latency...).

These techy thype issues are always the points at which equipment or processes become gold plated and hence usually too specialised or expense to actually yield their potential benefits. The Us approach to ADS-B seems so much more enlightened it does raise questions over the intelligence of EASA and EU authorities. If you give pilots some benefits from fitting this equipment - such as in-flight weather - fitment rates will be high. Compare and contrast with the current Mode S mess where because there are NO benefits (apart from maybe the partial one I mention at beginning) fitment rates are very low outside of Germany and the Netherlands - where it was a fit or be grounded issue.

[Rod1]

“The certification usually covers Mode S, as described in (E)TSO-C112.
However in general it does not cover the ADS-B specifications (E)TSO-C166b.”

Could you give examples of EASA approved Mode S units which support ES and do not have approval for ADS-B?

The cost of emitting ADS-B out in hardware terms, if you have a suitable transponder and a GPS with a suitable interface is the cost of an RS232 cable and 5 min setting up the user configurations. It is defiantly not allowed to do this on a permit aircraft. The LAA has recently been in discussions with the CAA over it. Special permission can be gained for short term testing but that appears to be dependent on having a RAIM capable unit.
The advantage to GA of emiting ADS-B out with SIL = low is it would save lives!

Rod1

[peterh337]

one of the few 'advantages' I could see in fitting a Mode S transponder is that I could radiate a GPS position and so gain some limited 'protection' form that.

Your best "protection" is to carry a Mode C (or Mode C/S) transponder and use it all the time. Then you will be visible to everything "turboprop and above" and quite a few well equipped piston planes, which all have conventional active TCAS (the sort you can install in GA for ~£15k). Despite official usage limitations in AOC ops, these active systems really do work. The only reason I don't have one is because the multiple antenna installation of an Avidyne 600 would mean a total strip-out of my cockpit and X weeks of downtime, where X starts when the last of the existing customers of the said avionics shop has finished screaming at them to finish his job

ADS-B is not used for TCAS purposes although it would be pretty good for it - like FLARM is which is basically ADS-B but non-ICAO

I don't see any point in complying with any future ADS-B unless they are mandated. Can any FLARM product receive ADS-B? If it could, that would be a plus.

An even better protection is to have an autopilot and use it, linked to GPS. Then you have almost zero head-down time and can keep a lookout for all those nontransponding planes OTOH if you fly above 2000ft, you avoid 99% of them anyway (seriously, there is a massive and very obvious correlation there).

The cost of emitting ADS-B out in hardware terms, if you have a suitable transponder and a GPS with a suitable interface is the cost of an RS232 cable and 5 min setting up the user configurations. It is defiantly not allowed to do this on a permit aircraft. The LAA has recently been in discussions with the CAA over it. Special permission can be gained for short term testing but that appears to be dependent on having a RAIM capable unit.

This has to be bollox because most planes not subject to Eurocontrol/EASA regs (which has got to be about 90% of world's aviation) will be emitting all this stuff when in EU airspace...

A requirement for RAIM for ADS-B emission is IMHO a misunderstanding of how GPS works. There are loads of situations where you use a GPS enroute but you can't get a RAIM computation. RAIM is a calculation entirely based on satellite geometry and is nothing to do with the equipment actually installed. You can do a RAIM prediction on your PC at home, for a given route and time.

If a GPS is good enough for nav then it is good enough for radiating your position on extended squitter or ADS-B.

It is widely known that Eurocontrol is full of techno boffins who produce 10,000 page documents which nobody understands. A while ago I was speaking to the dep. head of EASA at some presentation and he moaned that Eurocontrol documents need a wheeled trolley to move about. For every 500 page doc his outfit produces (which almost nobody can read, and I am sure it is intentional - vis the current 2 year derogation scandal) Eurocontrol produce 10,000 pages (which nobody at all can read).

[Rod1]

“This has to be bollox”

Which bit, the RS232 or the fact that the CAA have told the LAA no? Or somthing else entirely

Rod1

[Denti]

Can any FLARM product receive ADS-B?

Yup, Powerflarm for example can. And i'm sure there are others. Funkwerk offers a traffic monitor which primarily displays ADS-B info and has an interface to an external FLARM unit.

Many GA ADS-B installations send out a permanent NAC/NUC of 0 which means there is no integrity check (RAIM interface) and those positions will have to be disregarded by both traffic monitors and ATC. Current traffic monitor solutions might still display them without warning that the position may be wrong, which in itself is not a really safe solution.

DME/DME RNAV solutions can be BRNAV certified, we had that in our flight training aircraft (Cheyenne III) before we switched over to GPS, even certified for RNAV approaches down to RNP 0.5. FMS based DME/DME navigation was enough for PRNAV certification in our 737 3/500s and is enough to serve as PRNAV certified backup system in our NGs, except for RNP AR which requires switching off of VOR/VOR, VOR/DME and DME/DME updating.

Anyway, current (AMC 20-24) and future ADS-B regulation on installation in europe are aimed at commercial air traffic. There is not much for GA below 250kts cruise and less than 5,7t MTOW. That probably has to do with the amount of IFR traffic in those respective aircraft classes in europe as sadly GA IFR in SEP / light MEP is not really all that common.

[peterh337]

DME/DME RNAV solutions can be BRNAV certified, we had that in our flight training aircraft (Cheyenne III) before we switched over to GPS

As a matter of interest, what product did you have installed in there, and when was it?

traffic monitor solutions might still display them without warning that the position may be wrong, which in itself is not a really safe solution.

Does it matter, given that these products (Kinetic, etc) are used seemingly mostly for plane spotting?

What (if any) real purpose does ATC use ADS-B for in Europe?

Last time I spoke to Eurocontrol at some show they said ADS-B data is not used for any ATC purpose. Only primary and SSR radar is allowed for position determination.

Yes IFR GA is very thin, but then so is any traffic between say FL100-200 enroute. Many times I have done a say 700nm leg and never saw anything remotely near. That lower airways airspace is virtually empty, outside the terminal areas.

[Denti]

Well, eurocontrol runs the cascade program which deals with ADS-B in europe. However ADS-B is not (yet) used for primary control functions as far as i'm aware.

I wasn't talking about ground based traffic monitors but about the flightdeck based systems available now. Stuff like SBS-1 or others like that are indeed just a tool for plain spotters or the airplane noise brigade.

[peterh337]

What product did you have installed in the Cheyenne, and when was it?

[Rod1]

“What (if any) real purpose does ATC use ADS-B for in Europe?”

It may be used on the North Sea rigs for the helicopters but I have no official conformation of that.

ADS-B could be very useful in collision avoidance, but I will know more in a month or so.

BR,
Rod1