Help a US Controller Understand RAS...

[av8boy]

In an effort to educate myself as to the black magic of my ATC brethren in the UK, I've been doing some reading. Today I was looking at AIC 119/2006 (Pink 107) to try to work out RAS/RIS and draw analogies to ops in the US, and I saw this...

...Under a RAS the following conditions apply:
(a) The service will only be provided to flights under Instrument Flight Rules (IFR) irrespective of meteorological conditions;
(b) controllers will expect the pilot to accept vectors or level allocations which may require flight in Instrument Meteorological Conditions (IMC). Pilots not qualified to fly in IMC should accept a RAS only where compliance with ATC advice permits the flight to be continued VMC;
(c) controllers should be aware that pilots may not be qualified to fly in IMC although operating under IFR...

I double-checked MATS Part 1 (the nice new one coming out later this month) to ensure this wasn't an anomaly, and found the same info in Chapter 5, Section 1.4.

So, my question... How is it that you can have an IFR ticket in the UK but not be qualified to fly in IMC? This may just be something I've missed, in that I don't have an IFR ticket, but I've been in the business on the ATC side for 26 years and it's never occurred to me that someone licensed for IFR would not be able to fly in IMC.

Please, edumacate me!

Dave

[spekesoftly]

Dave,

Look at it this way. Pilots that are not quailified to fly in IMC may still elect to fly in accordance with the Instrument Flight Rules, outside controlled airspace.

[av8boy]

Perhaps I require a better understanding of what "...flight under Instrument Flight Rules (IFR)..." means in the UK. I got the impression from this:

(a) The service will only be provided to flights under Instrument Flight Rules (IFR) irrespective of meteorological conditions;

...that RAS required the aircraft to be on in instrument flight plan. Isn't a pilot on an instrument flight plan, by definition, capable of flight into IMC?

On the other hand, a VFR pilot flying in VMC and navigating via instruments isn't really flying under Instrument Flight Rules, is he? He's flying under Visual Flight Rules, right? Or where have I gone wrong?

Thanks for the help.

Dave

[rodan]

Anyone can fly IFR outside controlled airspace, as long as they comply with the Instrument Flight Rules which are (in the UK at least):

SECTION VI INSTRUMENT FLIGHT RULES
Instrument Flight Rules
28
(1) In relation to flights within controlled airspace rules 29, 31 and 32 shall be the Instrument Flight Rules.

(2) In relation to flights outside controlled airspace rules 29 and 30 shall be the instrument Flight Rules.

Minimum height

29
Without prejudice to the provisions of rule 5, in order to comply with the Instrument Flight Rules an aircraft shall not fly at a height of less than 1000 feet above the highest obstacle within a distance of 5 nautical miles of the aircraft unless:

(a) it is necessary for the aircraft to do so in order to take off or land;

(b) the aircraft is flying on a route notified for the purposes of this rule;

(c) the aircraft has been otherwise authorised by the competent authority; or

(d) the aircraft is flying at an altitude not exceeding 3000 feet above mean sea level and remains clear of cloud and in sight of the surface.


Quadrantal rule and semi-circular rule

30
(1) Subject to paragraph (2), in order to comply with the Instrument Flight Rules, an aircraft when in level flight above 3000 feet above mean sea level or above the appropriate transition altitude, whichever is the higher, shall be flown at a level appropriate to its magnetic track, in accordance with the appropriate Table set forth in this rule. The level of flight shall be measured by an altimeter set:

(a) in the case of a flight over the United Kingdom, to a pressure setting of 1013.2 hectopascals; or

(b) in the case of any other flight, according to the system published by the competent authority in relation to the area over which the aircraft is flying.

(2) An aircraft may be flown at a level other than the level required by paragraph (1) if it is flying in conformity with instructions given by an air traffic control unit or in accordance with notified en route holding patterns or in accordance with holding procedures notified in relation to an aerodrome.

(3) For the purposes of this rule ‘transition altitude’ means the altitude so notified in relation to flight over such area or areas as may be notified.

So a vanilla PPL can fly IFR (outside CAS) if he obeys those two rules (29 & 30) and remains VMC - flying IFR is a seperate issue from flying in IMC.
Hope that makes sense!

[Say Again, Over!]

Interesting discussion!

On this side of the pond, an aircraft we refer to as "flying IFR" is an aircraft on an IFR flight plan with a qualified IFR pilot at the helm.

Here, anybody can fly an airway and shoot approaches in controlled or uncontrolled airspace under VFR, so long as they do remain in VMC.

If you're not IFR certified, you cannot enter cloud. No matter what class of airspace you're in.

Semantics, I guess?

Felix

[spekesoftly]

Refreshingly uncomplicated, I wish!

[bookworm]

So, my question... How is it that you can have an IFR ticket in the UK but not be qualified to fly in IMC? This may just be something I've missed, in that I don't have an IFR ticket, but I've been in the business on the ATC side for 26 years and it's never occurred to me that someone licensed for IFR would not be able to fly in IMC.

Couple of differences to appreciate as background.

* The UK does not permit VFR at night. All flight at night has to be IFR or SVFR (in a control zone).

* The UK has very little class E airspace -- the vast bulk of low level airspace is A or G. IFR in class G is standard practice, is the only way of going through class G at night, and is based on (as rodan quoted) the quadrantal rule for keeping aircraft apart from each other and the minimum height rule for keeping aircraft apart from terrain and obstacles. Radar information and advisory services are available to reduce the residual risk.

With that in mind, it makes more sense to set licence privilege restrictions outside controlled airspace in terms of weather minima, not flight rules. Thus we don't have "IFR tickets" as such, at least for flight outside controlled airspace. A pilot without an instrument ticket of any sort is limited to a minimum flight visibility of 3 km.

...that RAS required the aircraft to be on in instrument flight plan. Isn't a pilot on an instrument flight plan, by definition, capable of flight into IMC?

The idea of an "instrument flight plan" is also alien to us for operations outside controlled airspace, at least in the way you think of it. Flights outside controlled airspace do not require a clearance to fly IFR, so they can switch at will between VFR and IFR (provided they obey one or the other). While a FPL can be submitted for flights outside controlled airspace, the initial choice of flight rules is not limiting.

All that said, except at night, it would be unusual for a flight operated visually by a pilot without an instrument ticket to claim to be IFR simply to receive a RAS.

Within controlled airspace, the UK is much more normal (if there is a "normal"). An instrument ticket is required for IFR, a FPL and ATC clearance is required, and IFR flights are separated by ATC.

Finally, worth adding that the RAS-only-for-IFR rule was introduced maybe 10 years ago. Previously, a RAS could be given to VFR flights -- IMHO that made a lot more sense: if you can't sight the traffic, you may need avoiding action, whether you're VFR or IFR.

[Knackers]

Seems that Downunder we follow the US/Canadian system.

So, in the UK, a VFR aircraft in G would call you up, tell you he's going IFR, you would then allocate a transponder code and input some flight plan details?

[av8boy]

It's beginning to make sense. Different system! Never would have guessed!

Called-up my best friend who is an ex flight instructor and, for the last 15 years or so, a pilot for Delta, and asked him about this. Shocked I say. Shocked. In the US an IFR rating automatically confers a right to fly in IMC, and you don't play the IFR thing unless you hold such a rating. Guess I wasn't as daft as I feared. Just a different way of doing things.

Thanks very much for all the info though...

Dave

[rodan]

In the US an IFR rating automatically confers a right to fly in IMC

As does an Instrument Rating in the UK. But just to re-iterate, no rating is required to fly IFR outside CAS if one is remaining VMC.

So, in the UK, a VFR aircraft in G would call you up, tell you he's going IFR, you would then allocate a transponder code and input some flight plan details?

Depends who 'you' is. There is no need for a flight plan to fly IFR outside CAS, and there is no need to speak to anybody either. 'So how is seperation ensured between two a/c in IMC who aren't talking to anyone?' I hear you ask. Well, it's a very big sky, you see...

[Knackers]

I like the Big Sky Theory...but the boss won't let me use it!

[BurglarsDog]

Ras V Ris

Hi a useful thread

But the Big sky theory dont always work in the UK; remember CARNO ; Jaguar tandem, doing 420kts low level, hit a lighty taking pics over the village of CARNO wales. Sad day for all and espeiually tragic as one of the jaguar pilots had recently returned to ops after a heart lung transplant.

Also the F15 s that sadly crashed in Scotland a few year back due in part to the misunderstanding of controller / pilot responsibilities under the British RAS service. All very sad so good that more understanding about some uniques practices is spread about a bit.

Im sure there are many on here more up to speed with todays specifics of the JSP522 and RAF ATC system but Ill try and put a bit of colour on the canvass from my memoirs of 10 years ago!!

Basically, ICAO based civil ATC separation is provided to acft according firstly to their status i.e. IFR or VFR/SVFR, and secondly according to the classification of airspace they are in at the time. So in class C, IFR and VFR are separated. But in class D; IFR v VFR are not separated and traffic info is passed. No sep standard needs to be proven as in class G no ICAO separation standard is required at all.

Now although the standard ICAO airspace classifications are used, the UK has a relatively small airspace, but with a high density and complexity of users. Controlled airspace, in the form of airways and control areas and zones is established around the country joining the major airports and linking the major inbound & outbound en route airways structure. Commercial acft therein and mil flying under civvy airways rules, are controlled by Civilian controllers as per the world over, applying the above separation rules.

However, the majority of airspace below FL240 (?) is uncontrolled; class G and this is the realm of the military ATCO. His / her rules of engagement are designed to meet the main users need i.e. Tactical Freedom.; e.g. this allows an aircraft to launch in Wales and fly low level to Scotland without filing a flight plan. The acft also has no legal requirement to seek an ATC service unless penetrating controlled airspace (I think). As already mentioned, under ICAO airspace classsification system, no separation is provided by ATC in class G . In most parts of the world, most users would predominantly be pilots flying under VFR anyway, in low density airspace (guessing here). However in the UK with poor weather, many fast movers, commercial jets going to airports not linked by CAS (Norwich?) ,and lots of inexperienced light aircraft some form of control is desirable.

So, firstly the UK has implemented a few rules and an additional standard to the IFR semicircular rule - known as the Quadrantal system; whereby any aircraft flying in IMC above the Transition level (fixed at FL30 in England & Wales I think? ( and therefore IFR qualified to do so) must fly at either an odd FL, an odd FL plus 500”, an even FL, or an even plus 500’ ; depending on his magnetic track; e.g. . 000-089degs 090 – 179 degs etc. Therefore , it is hoped that opposite direction traffic flying in IMC and in the cruise/ transit , dont meet.

Doesn’t do a lot for climbs and descents though.

So… and secondly, with a good overlap and base of radar coverage throughout the country the Mil ATC units and some civilian Lower airspace units, are able to provide a more effective separation / radar service on request to this multitude of airspace users.

Forget ICAO rules now.

On request, and in agreement with a controller, ( so subject to workload etc) , a pilot can
request either:
a Radar Advisory Service -RAS
a Radar Information Service or
a Flight Information Service from ATC.
Depending on his situation, tactical requirements, and weather conditions at the time.

Under a RAS, ATC pass 3D details of conflicting traffic along with advice necessary to resolve the confliction (climb descend turn) , where possible to achieve a standard separation distance –, 5 nm, 1000’ etc. There are also some specific and unique UK rules to using indicated mode C readouts for separation.


At all times the pilot is responsible for terrain avoidance - so ATC can only provide this service above a minimum vector altitude marked on the radar video map. Additionally as any instruction could take the aircraft into cloud (which ATC cant see) the pilot must be suitably qualified. These days he has to be IFR qualified to get a RAS - though 10 years ago in my day the term IFR wasn’t used or subsequently logged anywhere. There are also rules for the pilot to adhere to ; like not turning without advising ATC first ( as the same controller may have two opposite directions tracks at the same level and be vectoring them to achieve the 5nm sep for example. Any unplanned deviation by one would loose the standard sep. Once clear of the traffic the pilot is given a position update, advised to resume own nav has his RAS cancelled and generally he goes off freq back to his “quiet” operational frequency. So anyone taking this service can be vectored about a bit – which may cause a delay and not be strictly necessary on a rare sunny day.

A RIS on the other hand is more often requested by those happy to take their own visual separation and not wishing to take avoiding action instructions. Here traffic is passed and updated until clear. No maneuvering advice is passed and no sep standard has to be achieved. Onus is on the pilot. Acft can change heading without first advising ATC as no standard is being achieved other than pilot visal sep. This allows Tactical freedom for Fast Jet formations on a nice day and for light aircraft doing aerobatics etc..


Although this type of controlling is very reactive it is quite unique I think to teh RAF. (Please correct....) and alien to the Oz mil for example. But with no control over any airspace it works in the Uk ( for the most part). It makes the job very interesting and demanding when busy. But due to the lack of ICAOness ( e.g. no procedural standards of control) it results in a reporogramming of your ATC control technique theoretical knowledge chip necesary for anyone looking to leave the blue suite and join the civs in the UK. – unlike Oz where the same ICAO based MATS document, and rules and procedures etc are used by both sides.

Hope this expands a little on what’s already been said.

Happy to take corrections or PMs.


DogGone.





.

[bookworm]

So, firstly the UK has implemented a few rules and an additional standard to the IFR semicircular rule - known as the Quadrantal system;

FWIW I think the quadrantal rule used to be ICAO standard outside controlled airspace.

And it makes sense outside controlled airspace, as you're trying to use levels to separate even IFR flights from each other as much as possible. When you move to class E airspace, the situation changes: IFR flights are separated from each other by ATC, so the next priority is to separate the IFR flights from the uncontrolled and possibly unknown VFR flights using levels -- hence the ICAO semicircular rule.

[Spangly]

Although this type of controlling is very reactive it is quite unique I think to the RAF. (Please correct....)

Used to do pretty much this at Farnborough as a civvy. Very few (if any?) pilots understood that they had to be IFR if they wanted a RAS, but as they were outside controlled airspace, being IFR wasn't actually very onerous, and they don't even have to fly quadrantal levels if in receipt of heading instructions from a controller. Basically in that case, just observe the min height rule, and we wouldn't vector at an altitude below minimum radar vectoring altitude, so no problem there either.

[NorthSouth]

av8boy:
Another difference that might help you to understand it is that in the UK there are relatively few light aircraft pilots with a full Instrument Rating (what you might call an "IFR ticket"). Most PPLs with an instrument qualification have what's called an IMC Rating. This allows you to fly IFR in Class D and E airspace, including flying instrument approaches, but (a) you're not allowed to fly in airways (except the few bits that are Class D) and (b) you're not allowed to fly down to IR minima on approach, nor on takeoff. So your idea of anyone with an "IFR ticket" being able to do anything IFR doesn't fit over here.
As someone else said, IFR isn't a capability to fly in IMC; it's a set of rules which a pilot can choose to fly by irrespective of the weather conditions.
NS

[chrisbl]

and (b) you're not allowed to fly down to IR minima on approach, nor on takeoff. So your idea of anyone with an "IFR ticket" being able to do anything IFR doesn't fit over here.

Strictly it is a recommendation not to fly down to the charted minima rather than an outright prohibition.

[NorthSouth]

Strictly it is a recommendation not to fly down to the charted minima rather than an outright prohibition

For the vertical minima yes, but the 'no landing or takeoff in vis less than 1800 metres' is a legal requirement.
NS

[Scott Voigt]

Dave;

Don't feel bad about being confused... I have spent many hours plugged in at different UK facilities and it still confuses me from time to time about the different rules with the different airspaces... It is quite different from what you and I are used to, and there are far more areas of class G then we are used to... Our airspace and system actually seems much simpler for both pilots and controllers.

regards

Scott

PS. You ready to retire yet???

[BurglarsDog]

Bookworm.
If you have access to the docs,check Doc 4444 and ICAO Annex 2.
I dont think you will find the UK Quandrantal system defined therein. So it aint ICAO.
Also the Semicircular rule (which IS outlined within the ICAO Docs mentioned doesnt start until above FL240 (I think) . So not applicable in class E . This is / was designed to take into account pressure errors in altimetres at high level and afford an extra margin of safety on opposite tracks . i.e 2000 rather than the standard 1000' below the cut off altitude. With the implementation of RVSM the semi circular rule is becoming obsolete -unless of course aircraft arent fitted with the pre requisite of a more accurate transponder.
DogGone

[bookworm]

used to be

To be precise, the semi-circular table replaced the quadrantal table in Annex 2 Rules of the Air in 1966.

Also the Semicircular rule (which IS outlined within the ICAO Docs mentioned doesnt start until above FL240 (I think).

No, the semicircular rule as defined by ICAO applies above 3000 agl by default, to both VFR and IFR flights.

The UK "semicircular rule" is indeed quite different. It applies to IFR flights above FL245 outside controlled airspace, and thus appears to be as useful as a chocolate teapot.