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Primary radar
What a delightful days flying today although the sky was surprisngly quite.
With CAS hopefully I can see any traffic with a transponder - but is there any way of knowing if the unit you are working is / is not providing primary contacts as well? |
Let's assume you're receiving a RIS from a unit that has both primary and secondary radar. The controller calls traffic to you and intimates, "no height information." This could mean the traffic is an aircraft that has no transponder, has a transponder that isn't switched on, has a transponder which has no mode C capability or has a transponder with mode C capability but with the mode C deselected (for some reason, good or bad). If the unit is providing RIS based on SSR only the service should be limited for that reason because all they'll see are the squawkers. Keep those eyes peeled for the traffic the controller cannot "see".
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The only civil units that can provide a radar service without Primary radar are those within Controlled Airspace, and they can only provide that service within CAS. Once the primary goes outside CAS then you're going non-radar and you shouldn't get a radar service.
So - in answer to your question - YES, they can see primary contacts The military seem quite happy to provide a radar service without (mad!) but you will be told that traffic info will be given on transponding aircraft only. |
Chilli,
Most of the North Sea is covered by a Modified RAS, OCAS. On occasion (in fact most of the time) it is a Modified RAS SSR only. I have assumed that this is because there is unreliable or no primary contact. Is that an anomoly to the North Sea? |
Chilli
Thanks - hoped you would be along. So where a service is being provided by a CAS service provider but continues the service outside of CAS I understand from your reply that they would have primary. For example Gatwick will often provide a service outside of their class D. If the provider was unable to provide primary cover would they have to discontinue any service? Interesting point with regards the military. Presumably working Brise for example you are suggesting they might be providing you with a RIS but without primary cover? I am also interested to know how well hot air ballons show up on primary? Gatwick asked me to intercept and identify a ballon a while back but I subsequently wondered how well they were able to "see" it on primary. |
Perhaps not entirely on the subject of the original thread,but the right experts to answer this seem to be gathered on this thread.
Do modern 'plastic' light aircraft,built largely of GRP and CRP give a useable return at the full range of the primary surveillance radar? |
Originally Posted by Fuji Abound
(Post 4642191)
Gatwick asked me to intercept and identify a ballon a while back
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how did it respond to your "You have been intercepted, Follow me" signal? |
Most ATC units use both Primary and secondary radar.....lets assume you are recieving a RIS "Radar Information Service" the controller will advise you of traffic he see's, if its a primary contact he will still call it to you and probably advise it as such a contact.....if its a secondary contact with a mode "C" height readout will advise you of the contact and the height indicated but "unverified".
If he is using a secondary only radar ( i.e. here at Scottish using the Stornoway Radar) he will advise the service is limited to transponding aicraft only. |
If the provider was unable to provide primary cover would they have to discontinue any service? 1.6 Limiting a Service 1.6.1 Outside controlled airspace in circumstances where controllers cannot continue to provide the following primary requirements: a) traffic information and traffic avoidance in respect of all conflicting unknown aircraft for a radar advisory service; and b) traffic information in respect of all conflicting unknown aircraft for a radar information service, controllers may elect to continue to give the service by limiting the extent to which it is provided. 1.6.2 Controllers must inform pilots when they limit the service and ensure that pilots are made fully aware of the implications of any limitation. 1.6.3 In particular the service should be limited when: a) the aircraft is operating within 10 miles of: i) the edge of the radar display; ii) weather clutter; or iii) permanent echoes. b) the aircraft is operating in an area of high traffic density; c) the aircraft is operating near to the limits of solid radar cover; or d) the service is being provided using secondary radar only. |
Originally Posted by Droopystop
I have assumed that this is because there is unreliable or no primary contact. Is that an anomoly to the North Sea?
Originally Posted by Fuji Abound
So where a service is being provided by a CAS service provider but continues the service outside of CAS I understand from your reply that they would have primary. For example Gatwick will often provide a service outside of their class D.
If the provider was unable to provide primary cover would they have to discontinue any service? Interesting point with regards the military. Presumably working Brize for example you are suggesting they might be providing you with a RIS but without primary cover? I am also interested to know how well hot air ballons show up on primary? Gatwick asked me to intercept and identify a ballon a while back but I subsequently wondered how well they were able to "see" it on primary. |
Chilli,
Sorry, I refer to the areas covered by Brent, Sumburgh (OCAS), Aberdeen (OCAS) and Anglia Radars. |
Notwithstanding Spitoons posting , of the two civil SSR equipped units I've worked (one LARS outside CAS, one inside CAS who provides a pseudo LARS when the military go home) the first has no approval to work SSR only, the second is approved inside CAS only.
Droopystop - this is indeed a small anomaly as it is accepted that the likelihood of non-transponding traffic in these areas is miniscule, coupled with the fact that all participants in the HMR route structure will wish to participate in the ATC advisory service (RAS). Overland the situation is different. Some of us here however remember when there was a service being provided to traffic out to the East Shetland Basin using Secondary AND Primary ;) |
To summarise the above....
You have two options. Computer says YES. Computer says NO. |
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