Student question on RAS

[robdesbois]

Hi all, am a student for PPL(A), just brushing up on comms and procedures for my first solo land-away Saturday :eek::} and could do with a bit of clarification on something about Radar Advisory Service.

I'm using the JM Pratt PPL books, referring to the Comms one (which I passed a while back) reading about RAS, it says "...only available to aircraft operating under IFR...If the pilot is not qualified to fly under IFR, he should not accept an RAS where the controller's instructions might take the aircraft into IMC"

The first part is unambiguous - RAS cannot be given to a non-IFR flight.
The second part then seems a bit pointless. How can a pilot not qualified to fly under IFR accept a RAS regardless of whether instructions might take him into IMC or not? :confused:

Not that I'm going anywhere near controlled A/S this weekend but that one always confused me so thought I'd check it out.

Thanks!
Rob

[Knight Paladin]

Sounds like some IFR/IMC confusion to me, which has been discussed to death here before!

The point is valid though, although for different reasons - someone not qualified to fly in IMC really shouldn't be flying on a day when they need a RAS!

[robdesbois]

Dammit, I've been had by the IFR/IMC thing before...is it my confusion or the text's confusion?

So correct me if any of this is wrong (please :))

* IFR is simply operating under the minimum height, quadrantal and semi-circular rules
* as a VFR pilot I can fly IFR, but only in VMC
* an IMC rating / instrument rating is not a qualification to fly IFR, but a qualification to fly in IMC (obviously under IFR).

So the confusion here is that it should read "If the pilot is not qualified to fly under IMC" instead of "...IFR", as no qualification is needed to fly IFR.

...I'll get there eventually!
Thanks, rob.

[tmmorris]

You are pretty much right, yes. An IR qualifies you to fly 'in circumstances requiring flight under IFR' (my italics). The latter means it qualifies you to fly in IMC, and also in class A, since class A is IFR only.

An IMC rating (this won't come up in the exams which are JAR only, and don't mention UK only ratings) qualifies you to fly in circumstances requiring flight under IFR, in class D and below. So it qualifies you to fly in IMC, and to fly IFR in class D, since you don't need a rating to fly in class D VFR.

Confusingly, in the UK the IR and IMC ratings also reduce the VFR minima, to the ICAO ones you will learn anyway for your exam. In the UK a PPL is limited to 3k vis and 'in sight of surface.' But having the IR/IMCR means you can fly VFR on top, for example.

I'm sure I've forgotten something which someone will come along and point out, but that's the gist of it...

Tim

[IO540]

You've got it, more or less.

In UK airspace, a UK issued PPL can fly under IFR but only in

- Class G, and
- in VMC (3000m vis and clear of cloud, basically)

An RAS is available only to IFR flights in Class G.

And yes it could take you into IMC, in which case you have to refuse the instruction if you don't have an IMC Rating or an IR.

Practically, an RAS is of little value, because of the wide separation which ATC is obliged to apply. On the very days when you may want it (lots of traffic) they send you all over the sky.

I've noticed that jet transports tend to ask for RAS when in Class G, but they don't spend much time in Class G anyway.

RAS/RIS is a UK only thing; you can't get it elsewhere. Also, in every country I know of (except the UK and maybe Australia?) you need a full IR to fly IFR regardless of actual conditions.

[robdesbois]

Ok I'm more confident on the IFR/IMC distinction now and which ratings do what. Unfortunately when reading through the books it isn't necessarily that clear, but I think I'll re-read the relevant sections of law, they'll sink in better this time.


Thanks all for the help!
Blue skies, --rob

[bookworm]

* as a VFR pilot I can fly IFR, but only in VMC

Strictly that should read "as a pilot without an IR or IMC rating, I can fly IFR, but only in a visibility of at least 3 km and in sight of the surface".

It doesn't technically have to be VMC.

[Knight Paladin]

Rob - no worries mate, do always feel free to ask any more you may have. The aviation world seems to have a nasty habbit of strangling itself with as many rules and regulations as it can think of...

And before anyone gets on their high horse - yes, I completely understand and respect these particular rules and regs.

As regards commercial aircraft in Class G taking a RAS - it's not my field, but I've been told by friends that their operator requires them to take a RAS if available, whatever the weather. Hence the large numbers of them somewhat cheekily (IMHO) working the military area radar frequencies when outside CAS.

[Spitoon]

An RAS is available only to IFR flights in Class G.

And yes it could take you into IMC, in which case you have to refuse the instruction if you don't have an IMC Rating or an IR.
In fact, you have to refuse the service rather than a particular instruction.

The original question relates to text from a book which is ambiguous. I suspect what it was trying to say was "...only available to aircraft operating under IFR...If the pilot is not qualified to fly under IFR, he should not accept an RAS because the controller's instructions might take the aircraft into IMC".

[IO540]

That isn't much better, Spitoon :)

Every UK PPL, in UK airspace, is qualified to fly under IFR.

He just can't enter IMC.

One could thus well argue that a plain PPL should never even ask for a RAS, except in conditions where there is no possibility of entering cloud at anywhere near one's operating level, but I don't think that is the current CAA doctrine.

[Knight Paladin]

Spitoon - Sorry chum, you're wrong. Can't remember the reference, but somewhere in the rules for a RAS is states that you must immediately inform the controller if you are unable to comply with a particular instruction, and the example given is if that instruction will take you IMC. Vanilla PPLs are perfectly within their rights to request a RAS if they so wish.

[robdesbois]

Where is something like this officially documented for JAR? Other than CAP413, CAP493 and LASORS I don't really know any of the other CAA documents and which would be likely to contain this...

[mm_flynn]

All of the various 'official' versions of the rules on RAS I have seen have small inconsistencies in them due to the IFR vs IMC vs not-VMC intricacies of the UK PPL rating. However, the basic principle is simple - On a RAS you have contracted with a controller that he will vector you around the sky to avoid traffic by 1000ft/5 miles and you will do what he asks. If it is unlikely that you will be able to comply (i.e. any day there are clouds in the class G airspace and you are not IMC/IR rated) you shouldn't ask. As IO-540 said, on a clear day you shouldn't ask either as you will be vectored all over the sky! Unless you weight 100 tonnes and are sliding down the ILS into Coventry.

[Mariner9]

RIS/RAS I understand (well so I should having my ppl), but could someone explain what a Radar Control Service is?

Ta

[robdesbois]

According to CAP 493 (providing information on Air Traffic Services - found it!) an RCS may be provided to an aircraft operating under IFR, SVFR or VFR. The controller will issue instructions which:
* an IFR flight must comply with
* a VFR/SVFR flight will comply unless informing the controller otherwise
and is provided in controlled airspace only.

All is 'revealed' in CAP 493 sect 1.2-1.5
Fascinating reading :ok:

--rob

[Chilli Monster]

Mariner 9

Robdesbois has left out the most important bit:

RCS is only available inside Controlled airspace (it is in fact the only radar service available inside CAS - RIS/RAS being purely outside CAS).

Easy way to remember it:

RIS - we won't tell you what to do
RAS - we'll tell you what to do but you can refuse, in which case you go down to RIS
RCS - do as you're told!

[MikeJ]

I think its worth mentioning a little recognised feature of privileges of the UK PPL in UK airspace. I do not know what applies elsewhere.
An earlier post refers to the limit of 3k vis and sight of surface, and several have noted that within this limit, a 'vanilla' PPL can choose to fly VFR or IFR as he(she) wishes in Class D or below.
The absence of the vertical and lateral limits on distance from cloud makes little difference at or below 3000ft, but above that, the difference is very great. eg, if the cloud base is 4000', you may not fly VFR above 3000', even if the vis is 50k. The PPL without IR/IMCR is fully entitled to fly IFR in IMC in this space, provided the other IFR rules are met. We get a lot of days with 2-4 octas tops 4000-5000'. This allows the plain PPL to fly 'on top' in these conditions, provided he keeps the 3k forward vis, because of the gaps which allow him also to see the surface. It is impossible to get there VFR because of the inevitability of infringing the lateral and/or vertical limits when climbing/descending through the layer.
In my view it is both safer and much more relaxing to fly any reasonable distance at an appropriate quadrantal FL in visual conditions, than cope with all the various other flying activities and airspace restrictions below.
The NPPL specifies VFR only, as do the current limitations on permit a/c.
I think it an absurdity that under the very large area of the London TMA with a base of 3500', a cloud base of 4000' prevents VFR flight from using the invaluable extra 500' above 3000'. All areas under the TMA are very highly used, and every bit of space is needed. Quadrantal rules do not apply below the transition altitude, which there is 6000'.
Perhaps Bookworm would like to make further comment?
MikeJ

[robdesbois]

Chilli,

Au contraire, I said "and is provided in controlled airspace only." which I thought was quite unambiguous :}

I'm not sure about the RCS => "do what you're told", as according to the second point from CAP 493 an SVFR / VFR flight can choose not to comply with an RCS instruction and as for RAS must advise the controller.

Other than the meteorological conditions and controlled a/s requirements for RCS there doesn't seem to be much practical difference from RAS.

Reading between the lines I think that an RCS instruction that is not compiled with by an SVFR/VFR flight means the controller must plan otherwise; for an RAS it is the pilot who becomes responsible for separation if not complying with an instruction.

Yack!

[Chilli Monster]

My apologies - the way it was written made it look as if the "inside CAS" referred to VFR/SVFR only, due to the lack of punctuation. (I have just spent a 9 hour night shift providing RCS in CAS however and I'm always picky between night shifts!).

RCS is still basically "must do". If the pilot gets to the stage that he must deviate from the clearance for flight safety reasons, then they've left the decision that they can't comply too late. However, it's not a situation I've come across as you normally issue a clearance which is easily complied with, and gives decent scope for deviation whilst still complying with the clearance as issued.

Going back to the original question - RAS for VMC only pilots. I've had it asked before, either by someone who obviously didn't know what they were doing (R/T voices are a big clue) or it's been asked for below MSA / RMC minimum levels (below which you can't be vectored anyway). In both cases I would say don't waste ATC's time and ask for it in the first place (And in both the above scenarios you wouldn't get any more than a RIS from me).

[Knight Paladin]

Mike - bloody hell mate, that's a lot of thinking! Although you are very technically correct, I have to admit to having never thought about that before - if the airspace is there and, barring that particular rule, there are no other airmanship considerations precluding its use, I'd just go for it. Maybe that makes me a cowboy, I'd argue it actually makes me safer, so long as I'm not dangerously close to cloudbase and risking a confliction with anything descending out of the bottom.

As for following RCS instructions - you're still the captain of the aeroplane, and, as an instructor of mine would frequently say "air traffic are our servants" - but I'd have to have a bloody good reason to not follow their instructions, one that would probably either involve some form of aircraft emergency or the controller involved being about to have their ticket pulled!