"Limited Radar Service" what exactly is it

[IRpilot2006]

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?

[Widger]

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!

[Emma1974]

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.

[aluminium persuader]

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.
No cop-out at all, Widge. Under any service outside CAS, the pilot is ALWAYS where the buck stops. ATC has no jurisdiction over whatever may or may not be out there. There are a/c around designed specifically not to paint on radar, and there are also a lot of a/c that just dont paint well. Think wooden, glass fibre, small/no engine. It is by definition NOT a known traffic environment. Please don't get lulled into a false sense of security by having a radar service. You could very easily be given avoiding action on an a/c we can see which could turn you straight into the path of one we can't.
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.
ap

[ILS 119.5]

Was once flying into a small airport near Bradford and the Approach Controller was heard to be providing a Limited FIS. What's that?

[aluminium persuader]

A slip of the tongue? :\

ap:ok:

[Foxy Loxy]

QNH or RPS, alerting service and traffic info if/when able to pass such?

Foxy

[Standard Noise]

So that'll be a FIS then.

Limited FIS!? Never heard the like of it.

[Foxy Loxy]

Me neither. I have provided alerting service only, but that's exactly what I told the pilot I was providing.

I don't recall seeing "Limited FIS" in MATS1.

Foxy

[NorthSouth]

Two words. Ben MacduiBut that was nothing to do with limitation of service.
NS

[aluminium persuader]

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

[Bern Oulli]

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.

[chevvron]

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!!

[windyourneckin]

The only possibility is fis with limited traffic information due radar coverage, but this does not excuse controller ignorance :=

[orgASMic]

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.


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".

[Widger]

Orgasmic, you are absolutely correct but....it is still bo!!ocks!

[anotherthing]

Windyourneckin wrote


The only possibility is fis with limited traffic information due radar coverage, but this does not excuse controller ignorance


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

[Widger]

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.

[chevvron]

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

[anotherthing]

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!

[chevvron]

Acksherly Doc 4444 says a lot more than that; it says you may provide identified traffic with a service very similar to what we presently call RAS/what will be called de-confliction service! The next Para then describes the use of radar in the provision of Air Traffic Advisory Service!!!
So why isn't the UK following Doc 4444 chapter 8 guidance; why in fact did the DAP working group totally ignore this section of Doc 4444 when I pointed it out to them?
(Sorry thread creep)

[anotherthing]

Interesting stuff Chevvron - though I think the way we in the UK provide the three different services is good and provides an unambiguous (I think) differentiation. Unfortunately it does cause confusion when A/C from othwer countries get involved, therefore your suggestions may have some worth

[orgASMic]

I acknowledge that some people think that limiting a service is just an exercise in covering the controller's 6, but if you know that the picture is not as good or complete as it should be you need to tell the pilot. If you don't, you are leaving yourself wide open. It is negligent to mis-lead the pilot into thinking that the controller can see everything out there. Getting a radar service does not mean that the controller can protect the pilot from everything. Limiting the service reminds that pilot of that part of the contract you may not be able to fulfill. A lot of pilots do not know what their responsibilities are when in receipt of a radar service, nor the conditions that apply to the service.Similarly, reminding the pilot of his responsibilities with respect to terrain clearance when working at the MSFL or SSA is necessary as a lot of pilots don't know what their responsibilities are!

As for limiting a FIS - total hoop!

JSP 552 235.125.1 FIS is a non-radar service provided, either separately or in conjunction with other services, for the purpose of supplying information useful for the safe and efficient conduct of flight. Under a FIS the following conditions apply:

a. Provision of the service includes information about weather, changes of serviceability of facilities, conditions at aerodromes and any other information pertinent to safety.

b. The controller may attempt to identify the flight for monitoring and co-ordination purposes only. Such identification does not imply that a radar service is being provided or that the controller will continuously monitor the flight. Pilots must be left in no doubt that they are not receiving a radar service.

c. Controllers are not responsible for separating or sequencing aircraft.

d. Where a controller suspects, from whatever source, that a flight is in dangerous proximity to another aircraft, a warning is to be issued to the pilot. It is accepted this information may be incomplete and the controller cannot assume responsibility for its issuance at all times or for its accuracy.

[anotherthing]

'swat I said - without having the books to reference!

[IRpilot2006]

"Acksherly Doc 4444 says a lot more than that; it says you may provide identified traffic with a service very similar to what we presently call RAS/what will be called de-confliction service! "

That is what they seem to provide in France. An FIS but it's obvious they have you on radar and they give you traffic info with possible avoidance directions as necessary.

Why can't the UK do the same pragmatic approach?

The whole thing seems bound up with tight rules and it also looks like there are rules on whether an ATCO of a certain grade is allowed to see a radar screen.

[anotherthing]

IRPilot2006 - if you want a RADAR service in the UK......................don't ask for a FIS - how simple does it have to be?

Regardless of what happens in other countries, we do it our way. Who is right and who is wrong has nothing to do with it - it's laid down in black and white what each service provides, you as an IR pilot should know the services provided and conditions attached to each verbatim.

Start giving someone traffic info when they are on a FIS, and then when you are busy doing something else you omit to give traffic info and an incident happens, sure as eggs are eggs, the pilot will try to hang the controller.

All of the above does not take away a moral obligation that a controller may have if he thinks that staying quiet could be dangerous... i.e. giving traffic info to someone on a FIS is not inherently wrong, if it is deemed that there is a real risk of collision or very near miss (old style phrase), however we are not (or should not be) going to supply you with traffic info on anything that is going to puncture the 3/5 mile bubble!!

As an aside - in France (your example), under a FIS, if they give you avoidance instructions i.e. vectors, who is responsible for terrain clearance?

[IRpilot2006]

This is normally a VFR flight context, so there is no question about who is reponsible for terrain clearance - the pilot.

As regards asking for RADAR, come on boys you know it isn't that simple. One can get LARS, generally but not always, or a reluctant radar service from somebody else e.g. Thames.

[anotherthing]

IRPilot2006

We're at the point of going round in circles here, maybe you should visit a unit and they will explain things to you but......


As regards asking for RADAR, come on boys you know it isn't that simple. One can get LARS, generally but not always, or a reluctant radar service from somebody else e.g. Thames.


99 times out of 100, LARS is a service that is provided in addition to the main unit task i.e. if the unit has the manpower or capacity to provide it. If they refuse and give a FIS instead, it is usually for a very good reason.

Or would you rather be given a radar service by a controller who is unable to really give 100% to the task due to other commitments?

I am hopefully well off the mark here, but do you think that receiving a radar service means that you do not need to keep a good lookout? That's how it comes across!!

[IRpilot2006]

In the UK one could easily by in IMC in Class G; that's when most pilots would like a RIS. On a VFR flight one can change VFR/IFR at any time as required. Terrain separation is down to the pilot at all times when in Class G.

[anotherthing]

IRPilot2006

I think you are getting yourself confused... in earlier posts you extolled the virutes of the french system whereby you get radar derived traffic info and even avoiding vectors when receiving a FIS (paraphrasing your words from 4 posts ago)

In the UK you can receive a RIS or a RAS regardless of whether your are VMC or IMC... yo ucan have a RAS on a gin clear blue day if you so please, ... if you are a civvy, you need to be IFR to receive a RAS (I believe that's still the case..... I work in class A only now). These rules do not change what the service provides, nor the obligations of either the controller or the pilot.

Regarding terrain separation, we will not provide a RAS (i.e. a service under which we can issue vectors) to A/C flying below specified levels (used to be called radar vectoring charts, might still be), so yes you the pilot are ultimately responsible for terrain separation in class G, but we will not put ourselves in a position in the first place whereby we will vector you into Cumulus Granite-is.

None of what you have said makes any difference - if you want traffic called out to you, you ask for a RIS... if you want advisory headings to provide radar separation, you ask for a RAS. The receipt of either of those services does not negate the pilots responsibility to use the mark one eyeball to look outside as part of his overall scan (unless you are in really thick IMC, when it's a bit disorientating to do so!).

If you are happy looking out the window, and only want updated on major aerial activities, or strange weather phenomena or airfield unserviceabilities etc etc or want to participate in an alerting service - you ask for a FIS.

You can ask for a RIS or a RAS for any reason, a good one may be the fact that due to tasking, you are busy heads-down in the cockpit for longer than usual and are therefore not able to maintain the full lookout that you normally would.

FIS, RIS and RAS are laid down in black and white, they are very simple to follow, I for one do not understand why anyone should get confused.

[orgASMic]

Anotherthing - absolutely agree. It concerns me just how many pilots do not know what they are asking for when they request a radar service, nor what they can expect from each type of service.

One pilot receiving a RIS from me, on a gin clear day, complained that I had not called a particular contact to him, having already given him traffic information on the four or five contacts I thought were conflicting. (He was flying through a large stream iof gliders on a cross country competition). Having no one else on freq, I then called to him every one of those primary only contacts (about 20), especially the ones that were no confliction. He got the message.

The best (worst?) response I have had to the question "What type of service do you require?" was "Oh, just the usual". He got a FIS. Idiot.

As a footnote, you are correct that RAS is only available if operating IFR.

[Vick11]

The ICAO documentation was where the ATSOCAS working group started from. However, the provisions within ICAO allow the full range of options to be provided under the term FIS, including avoiding action. This did not accord with the Statement of User Requirement (SUR) that called for distinct service levels that were clearly defined and constrained. Therefore, it was not possible, practicable or desirable to simply adopt DOC 4444 principles (which are guidance not regulation) within class G in UK airspace. This was briefed and discussed at the Industry Workshop held on 8 May 07 and was agreed that the principle of adopting ICAO in total would not work for the UK.

Following the workshop the working group also considered what was done in other European countries and also the US. It was shown that there was no common standard for the application of services outside controlled airspace within Europe or between Europe and the US. Therefore, whilst the UK could have adopted one of the models, in actual fact it would only have standardised the UK with one other country and in reality none of their models actually answered thre requirements of the SUR.

However, to achieve greater compliance with ICAO the new suite of services will come under the overarching banner of FISs as desccribed in the RIA. Therefore, rather than 'not listen' I think it would fairer to say all avenues identified and suggested were explored, but at the end of day not everything people suggested proved to be pratical or implementable.