Whilst the country code-ranges are defined, each state has some lateral movement as to whether or not it opts to provide a direct lookup between its registrations and the range of the 24-bit address block allocated to it.

A number of countries have published algorithms or lookup tables covering the conversion. The UK is not amongst them. I have no idea how UK codes are allocated.

When a GTX330 is programmed on installation, the Hex number is the only external element which the installer is required to input. If hex code is within the US-allocated block, the transponder contains the algorithm necessary to set its own Tail Number. I don't have an electronic reference for that, but I do have the hard copy sitting in front of me.

2D

A quick look through the FAA library reveals the way in which the codes are allocated.

Loosely, the method is this:

Starting at N1 (code 50000001) the Hex code climbs sequentially with the N Number

N number sequence is alphabetical

N1
N1A
N1AA
N1AB
..
N1BA
..
N1BZ
..
N1ZZ
N10
N10A
..
N10ZZ
etc

Registrations containing I and O as letters are missed from the sequence and Discrete codes as shown on the N-number database are of course Octal (perhaps the source of your problem, Bookworm), so that you wont find any 8s and 9s.

I hope this helps.

Nigel

In that case, while ATC can get the tail number of an N-reg plane from the 24-bit return, how can they get the tail number of a non-N-reg plane?

Will every ATC radar outside the USA contain the algorithm which every possible country uses for the mapping of the 24-bit return to the tail number?

In any event, they won't get the aircraft details. The most they might get is the tail number. So, my original question is whether ATC (any ATC) is going to have a database lookup so they can see the aircraft details (or even just the aircraft type)

This too is fairly straightforward.

In addition to being able to decode the Hex code (where possible), the Mode S protocol provides for a second crew-programmable ID field. In commercial use, this will normally contain the Flight number (BAW1234) which will be set from the FMC before each flight. This is distinct from the aircraft's Hex code

It is unclear to me what the Garmin 330 returns in this field, but I can find out by putting a test kit on mine. I would guess that in the case of an N-reg, the field defaults to the same value as the implied Hex value.

ATC systems will, according to the Eurocontrol standards documents, be capable of determining the flight ID through a variety of means (4096-code as now via lookup, Hex code, and Crew-programmed code.) ATC will define the priority to give to each of these mechanisms and the system will highlight any inconsistencies.

Some form of lookup will still be necessary though for comprehensive translation of transponder/callsign - but this is nothing new.

2D

Help? How can it possibly help? It simply proves you right and me wrong. That doesn't help at all. ;)

Mode S LARS
 

Nipper 1... I guess anything's possible, you just need someone, who has the will, to find the money to go for such a reorganisation. Not too sure that in the big scheme of things LARS is too important an issue (personal opinion)... and the consensus seems to be that there would be resistance among the GA fraternity to having to pay a going rate for a LARS service so it is unlikely to be self funding.

(that's probably let another goat out!!!)

Sorry about the luddite comment, if that caused offence, it wasn't directed to you specifically though?

2D, my question remains unanswered. Will ATC have a database lookup?

You suggest that one might be necessary; that much I can see, since the transponder certainly won't return the data. By "nothing new" do you mean they already have a database lookup for aircraft details, given the callsign?

Come to think of it, U.S. radar units will need the same stuff, because plenty of non-N-reg planes fly to the USA.

It would be a good thing if ATC could see the aircraft type, weight, speed range, max POB.

IO540

I thought I'd already answered your question.

ATC already have a lookup. Obviously system details vary by country. In principle though, your squawk code (we are talking about controlled IFR flights here) is cross-linked to your flightplan. Your aircraft and details can therefore, to varying extents, be looked up automatically and details provided to the controller. At its most basic, this functionality is used to provide code-callsign conversion on radar displays.

Under Mode S, in principle, IFR Flights will all squawk 1000 and the Mode S data will provide the link back to the flight plan.

Implementation details will doubtless vary by country. What is certain though, is that a lookup table will be required to tie one or both of the Mode S ID fields (Hex Code or Programmed ID) to the Flight Plan. If Hex Code is relied upon (predominantly GA I would guess), the lookup table will need to be quite comprehensive.

2D

I don't think a "database lookup" is part of the plan, any more than you need a worldwide database of MAC addresses to surf the Net. The transponder will send the Flight ID, the radar system will display it.

Pierre Argh - no offence taken.

I think you will find that the GA community 'pays' for every service it uses and much more besides, through fuel duty and VAT on Avgas, neither of which the airlines pay.

What I am trying to do (and seem to some extent to have succeeded) is to try and start a discussion on ways that we, the people who are paying for all those Mode S sets can actually gain some benefit from them.

The CAA is activly seeking input right now. See http://www.caa.co.uk/docs/7/DAP_ORA_...nsultation.pdf if you want to have your say.

And bookworm, no I can't do it right now with mode A/C, no matter how many ATCOs there are. If I am working Solent and the other guy is working Farnborough (even though we are in the same piece of sky) all the information I get is 'contact in your twelve o'clock on reciprocal heading, height unverified not working this frequency". The Solent ATCO simply does not have the necessary information on his radar screen to help me. (Though perhaps I have misunderstood - maybe all those unverifieds are just aircraft with no Mode C?)

Now it may be that the new Mode S capable SSR they are currently installing for Solent Zone will include this capability in which case, non-too soon I say. Do you know about this Warped Factor?

2Donkeys gets close to the nub of the problem when he points out that NATS have not installed the equipment necessary to make the system really useful to us. No uplink, no cockpit information no ADSB etc. etc..

While here in the UK we are all bleating on about the cost of Mode S, in the USA pilots are willingly splashing the cash with their avionics shop to get the kit installed – even though it is not compulsory. Why? Because here the system is (rightly) perceived to have no real added value to the pilot in the (light) plane but is only there to serve ‘them’. This in turn has led to all kinds of conspiracy theories about what ‘they’ are up to. In the USA, the system has real, immediate and obvious value to the pilot so he spends his cash.

FAA 1: CAA 0

A fallacy I am afraid. The CAA and Air Traffic Service providers have to self fund through direct user charges, they don't get any of the tax revenues generated.

From the CAA website:

The Civil Aviation Authority (CAA), which is a public corporation, was established by Parliament in 1972 as an independent specialist aviation regulator and provider of air traffic services.

Following the separation_of National Air Traffic Services from the CAA in 2001, the CAA is now the UK’s independent aviation regulator, with all civil aviation regulatory functions (economic regulation, airspace policy, safety regulation and consumer protection) integrated within a single specialist body.

The UK Government requires that the CAA’s costs are met entirely from its charges on those whom it regulates. Unlike many other countries, there is no direct Government funding of the CAA’s work.

"Because here the system is (rightly) perceived to have no real added value to the pilot"

Very well said.

Having fitted a mode S some while ago as I commented early I have yet to find a unit that can even tell me if it is functioning correctly. Maybe the benefits will come, but given the comments here I am not holding my breath.

I have a friend who is an International representaive on the EMF (European Microlight Federation). He is not from the UK.

Switzerland has already said that it will not make Mode S mandatory for rag and tube aircraft in 2008, my friend tells me that Germany and Italy are about to do the same. The reason is health grounds with regards to radiation in non metalic aircraft.

If 4000 UK aircraft get exempt, it rather puts us back where we started. Not that Mode S really moved us anywhere in the first place, without tens, if not hundreds of millions spent on secondary radar capable of using it.

PPRuNe Radar is right.

Gordon Brown trousers all the Avgas tax and still gets a 6% return on everything the CAA does. Those of you who are fans of Mr Brown will perfectly understand the concept of this not being a tax, but rather a return on investment.

That said, the SES draft document specifically says that \'when considering charging for services, member states must take into consideration the revunue raised from duty on fuel used for aviation.\'

nipper1,

As PPRuNe Radar points out, nothing of the tax that you spend on avgas or anything else aviation related comes back to the CAA or NATS or any other UK ATC provider. They fund themselves through user charges.


In a word, no. I know what is meant to be happening at the LTCC, nowhere else.

WF.