"Limited Radar Service" what exactly is it
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"Limited Radar Service" what exactly is it
This is appearing increasingly today, UK OCAS obviously.
I normally read it back as "Limited radar, G-XXXX".
So I expect not to receive prompt reports of traffic.
But this is the case anyway. Often, under an RIS, one is given reports of contacts say 8nm away (which cannot be seen no matter what, at such a distance) but then something goes right past you.
Pilots who have TCAS say that loads of Mode C transponding contacts are not reported to the pilot by RIS.
Is "limited radar" some kind of legal liability disclaimer?
I normally read it back as "Limited radar, G-XXXX".
So I expect not to receive prompt reports of traffic.
But this is the case anyway. Often, under an RIS, one is given reports of contacts say 8nm away (which cannot be seen no matter what, at such a distance) but then something goes right past you.
Pilots who have TCAS say that loads of Mode C transponding contacts are not reported to the pilot by RIS.
Is "limited radar" some kind of legal liability disclaimer?
There are a number of occasions when ATC'ers etc may limit a service. Usually due to radar clutter, high traffic density, limits of radar cover, radar overhead, using SSR only and yes, you are right it is a disclaimer. There was a report I saw by the RAF ATCEB some time a go, stating that ithe use of the term "limited" was getting a bit excessive. I blame the instructors myself!
You will still get info as normal, but, should god forbid, the controller miss something, he/she can always say "ah but you were on a limited service". It is a cop-out in my opinion and used far too much.
On the subject of TCAS, you will generally not be told about traffic that is more than 3000' above or below as it is not a factor, you may however, still see it on TCAS. Also do not forget that TCAS is not very accurate in azimuth and the controller may assess that your relative courses are such that you will never conflict with the aircraft and so, not bother calling it.
This will probably all change when ATSOCAS is all shaken up and we re-invent the wheel!
You will still get info as normal, but, should god forbid, the controller miss something, he/she can always say "ah but you were on a limited service". It is a cop-out in my opinion and used far too much.
On the subject of TCAS, you will generally not be told about traffic that is more than 3000' above or below as it is not a factor, you may however, still see it on TCAS. Also do not forget that TCAS is not very accurate in azimuth and the controller may assess that your relative courses are such that you will never conflict with the aircraft and so, not bother calling it.
This will probably all change when ATSOCAS is all shaken up and we re-invent the wheel!
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I usually only limit service if a)i am using an SSR head only,so it is limited to transponding aircraft .;and b) if at the base of solid cover.
And i will call traffic thats 8 miles on your nose because it starts you looking for that typhoon closing at whatever speed they do.Would you rather wait til he is 1 mile 12 oclock same level?by the time the traffic info is given he would be on top of you.
We do our best.
And i will call traffic thats 8 miles on your nose because it starts you looking for that typhoon closing at whatever speed they do.Would you rather wait til he is 1 mile 12 oclock same level?by the time the traffic info is given he would be on top of you.
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should god forbid, the controller miss something, he/she can always say "ah but you were on a limited service". It is a cop-out in my opinion and used far too much.
Limiting a service is giving the pilot a "heads-up" that we may not be able to give him the high level of service we would like to, for any or all of the reasons Widge gave. It's a warning; not a cop-out.
I would perhaps agree that services are limited too much these days. However, as my Sup is wont to tell me - added value = added risk. If I don't limit the service & the worst happens, are you going to GUARANTEE that I will not end up in court?
Two words.
Ben Macdui.
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No. I was making the point that that's why (IMHO) controllers are quicker to limit the service these days, whereas before they may have battled on regardless.
ap
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I always taught that it was good practice to say in what way the service is limited. For instance if the aircraft is near the edge of the display and the bottom of radar cover, the controller might say "Limited Radar Information Service, little or no warning of traffic from below or from the South". However I would suggest that a large number of unknown returns is not a reason for providing a limited service, the service should be downgraded to a FIS. There is no such animal as a limited FIS. Unless of course the rules of the game have changed.
I know one unit which only gave limited FIS - Leavesden Approach. It was in their MATS Pt 2 (Station ATCIs as it was in those days) the reason being I believe due to the proximity of Elstree, Leavesden, Hatfield and Radlett- but then I may be wrong as someone usually points out!!
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If you are receiving a radar service from a military ATC unit, the controller will limit service:
a. When the ac is close to the lateral or vertical limits of solid radar cover, or within 10 nm of the edge of the radar display.
b. When the ac is close to areas of permanent echoes or weather returns.
c. When the ac is being flown in areas of high traffic density.
d. When a controller considers the performance of the radar is suspect.
e. When a controller is providing a service using SSR data outwith Class A airspace. Provision of RCS in Class A airspace using SSR only is to be specifically authorised in accordance with regulation 601.110.4a
f. Radar control may only be limited in MRSAs.
Note: Primary radar ‘solid cover’ is generally regarded as that portion of the radar's coverage within which a target of small reflecting area (i.e. Hawk) may be expected to paint satisfactorily.
But he should tell you why, where and for how long, ie
"Radar service limited from the left for 15nm as you pass close to the radar overhead".
or
"Radar service limited from below as you approach the base of radar cover".
a. When the ac is close to the lateral or vertical limits of solid radar cover, or within 10 nm of the edge of the radar display.
b. When the ac is close to areas of permanent echoes or weather returns.
c. When the ac is being flown in areas of high traffic density.
d. When a controller considers the performance of the radar is suspect.
e. When a controller is providing a service using SSR data outwith Class A airspace. Provision of RCS in Class A airspace using SSR only is to be specifically authorised in accordance with regulation 601.110.4a
f. Radar control may only be limited in MRSAs.
Note: Primary radar ‘solid cover’ is generally regarded as that portion of the radar's coverage within which a target of small reflecting area (i.e. Hawk) may be expected to paint satisfactorily.
JSP552 235.135.2-3
But he should tell you why, where and for how long, ie
"Radar service limited from the left for 15nm as you pass close to the radar overhead".
or
"Radar service limited from below as you approach the base of radar cover".
Last edited by orgASMic; 1st Nov 2007 at 15:16. Reason: spelling
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Windyourneckin wrote
I beg to differ but you can give a full FIS irrespective of whether or not you have radar... radar has nothing to do with FIS.
It's no wonder pilots get confused when controllers start to give traffic info when supplying FIS if it's done by the book - that's what a RIS is for... even under a RIS, collision avoidance is the pilots responsibility, and if the controller for some reason does not call certain traffic, it's still the pilots responsibility!
Many controllers will, if they have individual squawks available for FIS traffic abnd therefore have them identified and have maintained track identity, pass information on traffic which will be very close.... but only when they are quiet enough....
Chevron -
I would have thought that it was pointless to limit FIS even in the example you cite... FIS is a very basic service (as you know), telling A/C from leavesden "caution, x,y,z airport is active" or something similar would cover all that they would need to be told.
NorthSouth
The incident you mention has nothing to do with limiting RIS or RAS it's more to do with interpretation of responsibility under different radar services and even moreso to do with the lack of similarity between operating procedures of NATO military forces
The only possibility is fis with limited traffic information due radar coverage, but this does not excuse controller ignorance
It's no wonder pilots get confused when controllers start to give traffic info when supplying FIS if it's done by the book - that's what a RIS is for... even under a RIS, collision avoidance is the pilots responsibility, and if the controller for some reason does not call certain traffic, it's still the pilots responsibility!
Many controllers will, if they have individual squawks available for FIS traffic abnd therefore have them identified and have maintained track identity, pass information on traffic which will be very close.... but only when they are quiet enough....
Chevron -
I would have thought that it was pointless to limit FIS even in the example you cite... FIS is a very basic service (as you know), telling A/C from leavesden "caution, x,y,z airport is active" or something similar would cover all that they would need to be told.
NorthSouth
The incident you mention has nothing to do with limiting RIS or RAS it's more to do with interpretation of responsibility under different radar services and even moreso to do with the lack of similarity between operating procedures of NATO military forces
ATC'ers are in danger of becoming a bunch of lawyers with clauses for this and regs for that, losing sight of what matters:
Preventing collisions between aircraft and between aircraft and obstructions.
Preventing collisions between aircraft and between aircraft and obstructions.
anotherthing:
See ICAO Doc 4444 chap 8 para 8.11 'Use of Radar in the Flight Information Service'
The Leavesden example certainly happened; I can remember discussing the legality of it at a GATCO Technical Committee meeting
See ICAO Doc 4444 chap 8 para 8.11 'Use of Radar in the Flight Information Service'
The Leavesden example certainly happened; I can remember discussing the legality of it at a GATCO Technical Committee meeting
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Chevvron - I don't have the document at home but I can imagine it goes along the lines of
"radar may be used by the controller to identify an A/C for his own purposes... this identification does not infer that a radar service is being provided" (dragged out of the back of my brain - it's a couple of years since I did LARS)
... You do not need a radar to provide a full FIS... and I am with Bern Oulli - I doubt if there is such a thing as a limited FIS in the book(leavesden notwithstanding),
Surely your example was more a way for Leavesden to inform people that they might not get afforded even the 'full' attention that FIS normally gets(??) - i.e. an alerting and information service - nothing to do with radar, more to do with nav warnings, warning a/c that are believed to be in the relevant area of any major air activity that is known to the 'controller' etc etc and also liaising with radar units/D&D as part of an alerting service
Widger -
There is nothing wrong per se with the limitation of a service - it is very valid when operating near the theoretical base of radar or in areas of known clutter etc - it should not be used as a get out for giving a gash service, but it should be used for as it is intended... to inform pilots that some intruder that in one direction (from below/the west etc etc) radar coverage is not ideal to guarantee that an ATCO will see all traffic.. it helps a pilot who will then spend a bit more time with the mark one eyeball in those areas.
I would go in totally the opposite tangent from you in this matter - I would say that an ATCO was negligent if he omitted to tell a pilot that the radar service he/she was getting may be degraded in some way!
"radar may be used by the controller to identify an A/C for his own purposes... this identification does not infer that a radar service is being provided" (dragged out of the back of my brain - it's a couple of years since I did LARS)
... You do not need a radar to provide a full FIS... and I am with Bern Oulli - I doubt if there is such a thing as a limited FIS in the book(leavesden notwithstanding),
Surely your example was more a way for Leavesden to inform people that they might not get afforded even the 'full' attention that FIS normally gets(??) - i.e. an alerting and information service - nothing to do with radar, more to do with nav warnings, warning a/c that are believed to be in the relevant area of any major air activity that is known to the 'controller' etc etc and also liaising with radar units/D&D as part of an alerting service
Widger -
There is nothing wrong per se with the limitation of a service - it is very valid when operating near the theoretical base of radar or in areas of known clutter etc - it should not be used as a get out for giving a gash service, but it should be used for as it is intended... to inform pilots that some intruder that in one direction (from below/the west etc etc) radar coverage is not ideal to guarantee that an ATCO will see all traffic.. it helps a pilot who will then spend a bit more time with the mark one eyeball in those areas.
I would go in totally the opposite tangent from you in this matter - I would say that an ATCO was negligent if he omitted to tell a pilot that the radar service he/she was getting may be degraded in some way!