UK: airways squawks and code-callsign conversion
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UK: airways squawks and code-callsign conversion
I'm a UK ATCO in a regional airport with some technical knowledge, but not enough to answer this question myself.
All of our airways arrivals and departures are allocated a squawk, presumably either a domestic or ORCAM code depending on route and destination. All of our airways traffic passes through the airspace of a nearby airport whose ATSU is run by NATS, and they pass the relevant squawks to us by phone when they are allocated. They receive the squawks on a computer screen or printed on the strip - I forget which. In addition, they use what I assume is the same data to code-callsign convert every domestic and ORCAM squawking contact on their radar displays.
Given the increasing volume of airways traffic we handle, and the necessity of coordinating a lot of our traffic, we have asked NATS for a source of squawk data to eliminate the phone calls and other hassle, and apparently, the answer was 'No - it's commercially confidential.' Now, obviously that can't be right because (a) there's nothing confidential about civil squawk allocations, (b) they're giving us the data on the phone anyway, and (c) it implies that NATS en-route are providing essential operational data to NATS airports that they won't provide to non-NATS airports, which would be anti-competitive. In addition, a nearby military LARS unit have recently been given a feed of squawk data which has allowed them to code-callsign convert all airways traffic on their radar, so it must be possible for us too.
So the question is, exactly where are the squawks allocated, and how does a non-NATS airport obtain a feed? Reliance on phone calls is working 85-90% of the time at the moment, but will become less reliable in the future given forecast traffic figures. I'm sorry if it seems to be a pretty basic question, but research to date has only thrown up excuses, as above. All practical comments very welcome.
All of our airways arrivals and departures are allocated a squawk, presumably either a domestic or ORCAM code depending on route and destination. All of our airways traffic passes through the airspace of a nearby airport whose ATSU is run by NATS, and they pass the relevant squawks to us by phone when they are allocated. They receive the squawks on a computer screen or printed on the strip - I forget which. In addition, they use what I assume is the same data to code-callsign convert every domestic and ORCAM squawking contact on their radar displays.
Given the increasing volume of airways traffic we handle, and the necessity of coordinating a lot of our traffic, we have asked NATS for a source of squawk data to eliminate the phone calls and other hassle, and apparently, the answer was 'No - it's commercially confidential.' Now, obviously that can't be right because (a) there's nothing confidential about civil squawk allocations, (b) they're giving us the data on the phone anyway, and (c) it implies that NATS en-route are providing essential operational data to NATS airports that they won't provide to non-NATS airports, which would be anti-competitive. In addition, a nearby military LARS unit have recently been given a feed of squawk data which has allowed them to code-callsign convert all airways traffic on their radar, so it must be possible for us too.
So the question is, exactly where are the squawks allocated, and how does a non-NATS airport obtain a feed? Reliance on phone calls is working 85-90% of the time at the moment, but will become less reliable in the future given forecast traffic figures. I'm sorry if it seems to be a pretty basic question, but research to date has only thrown up excuses, as above. All practical comments very welcome.
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I'm sure a more technical answer will be along soon, but here goes:
The en-route squawks are allocated to NATS en-route by NAS (the national airspace computer). This draws the squawks from either its own database or, if relevant, a number or ORCAM squawks which are allocated to it and which go with the flight until it lands or is allocated a new squawk in another country down the line.
To prevent two aircraft potentially having the same squawk in the same airspace, squawks have a 'life' on them based upon the flight plan. They cannot be reallocated until this life has naturally expired or they are manually marked as available for use (something we have to do if NAS is off-line).
For these reasons, the control of the allocation of en-route squawks has to rest with one body, in this case NATS. In addition, the only real way an airport can get access to these codes 'on-line' is through the provision of a link into NAS. Giving this to non-NATS airports carries a risk of destabilising NAS (it can be a bit vulnerable to data which is not put in in exactly the right format and you don't know it's wrong until NAS falls over and everyone gets asked to stay on the ground!) by personnel who are not trained by or accountable to NATS. It's like giving your internet password to a neighbour and asking them to take care with your logins!!
NATS airports are different because NATS has some influence and control over the training, accountability and level of access of these airports.
Hope this helps a bit.
The en-route squawks are allocated to NATS en-route by NAS (the national airspace computer). This draws the squawks from either its own database or, if relevant, a number or ORCAM squawks which are allocated to it and which go with the flight until it lands or is allocated a new squawk in another country down the line.
To prevent two aircraft potentially having the same squawk in the same airspace, squawks have a 'life' on them based upon the flight plan. They cannot be reallocated until this life has naturally expired or they are manually marked as available for use (something we have to do if NAS is off-line).
For these reasons, the control of the allocation of en-route squawks has to rest with one body, in this case NATS. In addition, the only real way an airport can get access to these codes 'on-line' is through the provision of a link into NAS. Giving this to non-NATS airports carries a risk of destabilising NAS (it can be a bit vulnerable to data which is not put in in exactly the right format and you don't know it's wrong until NAS falls over and everyone gets asked to stay on the ground!) by personnel who are not trained by or accountable to NATS. It's like giving your internet password to a neighbour and asking them to take care with your logins!!
NATS airports are different because NATS has some influence and control over the training, accountability and level of access of these airports.
Hope this helps a bit.
Surely there is no need for access to input to NAS to have data made available. Considere a radar with code-callsign conversion. The data comes from NAS/CCDS and is presented to a controller, who has no opportunity to push the edges of NAS operational programme. Likewise, when EFPS presents data to the controllers, there is no chance for them to cause danger to NAS.
I suspect that the only barrier is financial. NATS sees potential to sell data and make $$$ and your management only have $ to offer, so you have been spun some technical mumbo jumbo yarn to save faces and will be left hanging on the telephone until such a point that your management and NATS accountants see eye to eye. I suspect that this will eventually happen as future ATC concepts will depend on it.
I suspect that the only barrier is financial. NATS sees potential to sell data and make $$$ and your management only have $ to offer, so you have been spun some technical mumbo jumbo yarn to save faces and will be left hanging on the telephone until such a point that your management and NATS accountants see eye to eye. I suspect that this will eventually happen as future ATC concepts will depend on it.
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Thanks for the replies. eyeinthesky - a very clear description of the system, thanks. Agree with Dan Dare - there's no need for an airport to input data to code-callsign convert or incorporate issued squawks into an airways clearance. Similarly with the case of the nearby military LARS unit, they won't input any data themselves and have been allowed a feed of the data, even though they're not NATS and therefore 'unaccountable'. I'm also not aware of any money having changed hands in this case.
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Giving this to non-NATS airports carries a risk of destabilising NAS (it can be a bit vulnerable to data which is not put in in exactly the right format and you don't know it's wrong until NAS falls over and everyone gets asked to stay on the ground!) by personnel who are not trained by or accountable to NATS. It's like giving your internet password to a neighbour and asking them to take care with your logins!!
Maybe I am misunderstanding here, but if NATS can install this recieve only link at its own airfields why can't it do so for non-NATS units? I agree with the original poster, we spend a lot of time passing squawks over the phone to other airfields (maybe we at at the opposite ends of the same phoneline?!) and operationally it would be much better if they could have a direct link.
I suspect as suggested above, it comes down to NATS and £££.
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With the system for distributing pairing information to RDPs that was installed in the late 80s, there was a shortage of communications ports and they were all used up by the mid 90s (NSL airports had to use some data splitters to get information to some of their newer systems). The sytem was replaced a couple of years ago, so there should not be a capacity problem - no doubt NSL will sell the data for a small(?) fee.
The input side is more problematic, but the Single European Sky Regulations presumably will mean that NATS will have to offer input and output data facilities to non-NATS airports on the same terms as they are provided to NATS airports and the interfaces will have to conform to some interoperability rules. HOWEVER, the current systems are limited and use arcane interfacing protocols so non-NATS airports will have to wait until they are replaced (and wait, and wait, and wait ...)
The input side is more problematic, but the Single European Sky Regulations presumably will mean that NATS will have to offer input and output data facilities to non-NATS airports on the same terms as they are provided to NATS airports and the interfaces will have to conform to some interoperability rules. HOWEVER, the current systems are limited and use arcane interfacing protocols so non-NATS airports will have to wait until they are replaced (and wait, and wait, and wait ...)
If a UK Mil airfield is receiving SSR from a NATS source, it will get CCDS too ie they don't have to input a conversion locally; that's the package MOD pay for. Some NATS airports also receive CCDS but only if the airport authority pays for it (with one exception).
So slowclimber, your airport authority will have to pay for whatever it wants, that includes renting telephone lines to carry the info and the modem to extract the info from the data sent to you.
So slowclimber, your airport authority will have to pay for whatever it wants, that includes renting telephone lines to carry the info and the modem to extract the info from the data sent to you.
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The business interests of nats limited puts money above safety again!
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Thanks again for the comments. I agree with aerotech07 that input to NAS is irrelevant - we have no need to do this. From all that has been explained, I can't see any technical reason or principle why our particular airport can't receive the relevant data feed, aside from cost. Would it be hopelessly optimistic to think that we could obtain this data to speed up and improve coordination with the various NATS units/sectors that use our moderately busy corner of CAS, and waive the cost on the basis of removing significant workload from the NATS units concerned?
Chevvron - in the case I mentioned, the military LARS unit uses a network of military radars and don't buy in NATS radar data at all. They have recently acquired data from NATS to code-callsign convert, and I believe it has been put in place in order to make coordination between the unit and NATS en-route quicker, without charge. They aren't a source of airways arrivals or departures themselves but handle some airways joins as part of their LARS function - as we do.
I would argue that the system is already paid for by route charges incurred by every aircraft that uses the system. Why charge twice, especially when passing the data by phone achieves the same result without charge at a greater administrative burden to NATS themselves?
If a UK Mil airfield is receiving SSR from a NATS source, it will get CCDS too ie they don't have to input a conversion locally; that's the package MOD pay for.
This stuff all costs money and somebody has to pay for it. Why shouldn't the airport pay its share of the costs ?
Last edited by slowclimber; 20th Apr 2010 at 22:03.
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There seems to be some confusion between obtaining SSR codes for aircraft departing your airfield and CCDS data for code callsign conversion on the radar.
The first requires access to NAS which is difficult because it was never designed to support the type and number of systems that now connect to it. Getting that access is pretty unlikely so you are probably going to be troubling the nearby unit until 2013. After then the UK will be using the European centralised code allocation system and you'll probably be able to get those codes direct from them provided your airport is willing to invest in the systems required to do that. Shortly after that NATS will be replacing NAS with a new FDP system which will support connection to other units as required by the Interoperability Regulations. Again your airport will be able to connect to that if it invests in systems able to do it.
As others have already said NATS does make CCDS data available for code callsign conversion, usually in conjunction with the SSR data but also on its own for those who have their own SSR. There are significant costs in additional equipment, software maintenance and support to allow that access and NATS is allowed to recover those costs plus a contribution towards the system itself to reflect the use of that system. NATS isn't allowed to use en-route charges to subsidise the NSL airports and has to charge them the true cost of providing that service so it seems only reasonable that other airports should pay as well.
The NERL en-route charge does not contain an element to pay for services provided for airports. If you want that to happen you need to lobby the CAA although you might be a bit late for the next charging period.
As part of its contract with NATS for the provision of ATC infrastructure the MOD has already paid its fair contribution towards CCDS and other data feeds.
The first requires access to NAS which is difficult because it was never designed to support the type and number of systems that now connect to it. Getting that access is pretty unlikely so you are probably going to be troubling the nearby unit until 2013. After then the UK will be using the European centralised code allocation system and you'll probably be able to get those codes direct from them provided your airport is willing to invest in the systems required to do that. Shortly after that NATS will be replacing NAS with a new FDP system which will support connection to other units as required by the Interoperability Regulations. Again your airport will be able to connect to that if it invests in systems able to do it.
As others have already said NATS does make CCDS data available for code callsign conversion, usually in conjunction with the SSR data but also on its own for those who have their own SSR. There are significant costs in additional equipment, software maintenance and support to allow that access and NATS is allowed to recover those costs plus a contribution towards the system itself to reflect the use of that system. NATS isn't allowed to use en-route charges to subsidise the NSL airports and has to charge them the true cost of providing that service so it seems only reasonable that other airports should pay as well.
The NERL en-route charge does not contain an element to pay for services provided for airports. If you want that to happen you need to lobby the CAA although you might be a bit late for the next charging period.
As part of its contract with NATS for the provision of ATC infrastructure the MOD has already paid its fair contribution towards CCDS and other data feeds.
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Thanks eglnyt, that clears things up. I had made the assumption that squawk data for assigning to aircraft, and squawk data for code callsign conversion were the same thing - I didn't realise that there were two different systems.
Changing the original open question, then: assuming from the above comments that all NATS airports use CCDS, which other airports do, and which have access to NAS? I'd be interested to see if there's a level of airways traffic above which CCDS and NAS seem to be essential, and what that level might be. I'd be happy to receive PMs if people don't want to post about their unit on the open board.
Changing the original open question, then: assuming from the above comments that all NATS airports use CCDS, which other airports do, and which have access to NAS? I'd be interested to see if there's a level of airways traffic above which CCDS and NAS seem to be essential, and what that level might be. I'd be happy to receive PMs if people don't want to post about their unit on the open board.
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Where/how do you get your clearances/releases........or to whom do you notify pending departures?
Is the NATS unit acting as a kind of "agent" ?
Is the NATS unit acting as a kind of "agent" ?
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When the NATS airport in question is closed, we get clearances from TC or airways (depending on direction of departure). When they're open, we have to ask them for the clearance instead. Both airports are in contiguous CAS.
