CAS transit

[VMC-on-top]

If I want to transit CAS (assume class D) I call approach / radar and ask for VFR clearance to transit - which is usually given depending on traffic. However, I have an IMCr so :-

1. Am I more likely to get a faster / better clearance if I ask for "IFR transit" or "vectored transit" - and is there such a thing?

2. If the answer to (1) is "only VFR", and I want to transit CAS but it is partially in IMC, if I continue through the IMC, am I doing so unlawfully? ie. do I need to request descent / climb to avoid the IMC or can I become IFR part way through my VFR transit?

[Roffa]

1) Nothing to stop you asking for IFR but that means you need to be separated from other IFR traffic which may actually make the transit more difficult. VFR only needs traffic info on IFR.

2) If you're VFR and given a VFR transit the clearance phraseology should be...

Cleared from (place) to (place) VFR via (routeing) not above (level), maintain VMC while in the (name) control zone.

Note the bold. You can't change to IFR at your own whim, it needs to be done by agreement with ATC and well before any possibility of going IMC as there are separation implications in doing so, both from other aeroplanes and from the ground.

If you want IFR, ask for IFR. If you want VFR, ask for VFR. Changing from VFR to IFR once inside the CAS is probably not the best plan and should be avoided if at all possible.

[IO540]

One is IMHO more likely to get a transit (or indeed a radar service OCAS) if one sounds like one is on the ball. This means

- IFR rather than VFR
- reading off an "obviously IFR" route e.g. one based on intersections/navaids rather than silly village names :)
- on the ball radio manner

I think UK ATC denies (officially) there is any effect but they cannot possibly deny it abroad :)

[VMC-on-top]

So, is there any advantage to asking for IFR transit? - Understood, IFR separation is greater, so by definition the likelihood of getting IFR clearance is likely to slow down the process of getting a transit, right?

So, if i get an IFR transit, how would it be phrased? - Presumably, not the same as VFR ie "from X to Y not above Z", but it would be by vectors, right? - then "resume own nav" when on the other side?

[IO540]

You ask for an IFR transit and if they give it to you, they will tell you where they want you. Simple :)

That's why people spend half their life getting the IR - so they can fly everywhere just following instructions ;)

You will be in CAS so you will get a Radar Control Service as soon as you cross the line into CAS (and be ready to read that one back).

They might let you cross on your original track but equally likely they will give you a heading. If they give you a heading they may ask for your current heading first.

Sometimes they ask your heading and you reply say "240" and they say "G-XXXX radar heading 240" which may sound odd (why did they bother?) but it means that your lateral clearance is now that heading and no longer the previous route (even if the actual heading has not changed). (the word "radar" is optional and fairly meaningless and is supposed to remind you of the Radar Control Service, AFAIK).

In the same vein you might be at FL040 (with a QNH of 1012 applicable but you have obviously set 1013) and they might give you the transit at 4000ft on a QNH of 1012... again you may wonder why but they just happen to work in feet :)

That's an important bit to understand about IFR or indeed any flight in CAS. Your lateral clearance is quite separate from your vertical clearance.

But basically you just do what ATC tell you - and always remember the above para and be very clear to

- maintain your most recent lateral clearance, till you get another one
- maintain your most recent vertical clearance, till you get another one

[VMC-on-top]

Is there an expectation that if I ask for IFR transit that I may be asked to transit through class A IFR? In other words, would there / could there be a situation that I get "blocked" by class A - and so could I ask for "transit through class D only"?

[Roffa]

IO, it should just be 'continue present heading', anyone sticking the word 'radar' in there is wasting a couple of syllables and needs to revise their r/t.

VMC-on-top, an ad-hoc IFR transit is 99% likely to be radar vectored to ensure separation from other traffic. So radar vectored through the CAS then released to own nav again (with confirmation of your position) when popping out the other side.

Now, something else to bear in mind. If you were to request an IFR clearance through Gatwick's local airspace for example levels will be allocated to ensure the separation requirements so, after all the identification stuff, confirmation of IFR etc the clearance might come back as 'cleared to enter CAS, fly heading 240 degrees climb to altitude 3,000ft on QNHXXXX'.

Now, with your IMC rating only qualification, what's the problem?

[ak7274]

Slightly off topic, but being a paranoid so and so, do ATCO's have a black book?
By this I mean when applying for a Zone transit obviously being on ones best behaviour and trying ones best to be a good boy on the radio, do they/you mutter under their/your breath "Oh no not him again " and lean more towards a refusal if us armatures are in the book.
I do try my best, Honest injun, but sometimes having asked for a transit think Sheet, that was not good and expect a polite refusal. Do you have my C/S in your black books?.....No not telling you :confused:

I must say however that contrary to many horror stories about those dreaded atco's they have been very helpful on most occasions , not all, but most.

[Roffa]

Didn't notice your last post as I typed. Yes, you'd need to specify that you can only accept an IFR clearance in the Class D airspace.

The controller will probably not otherwise be aware of the limitations of the IMC rating even should you mention that's what you have, it's up to you to ensure you fly within your privileges.

[IO540]

IO, it should just be 'continue present heading', anyone sticking the word 'radar' in there is wasting a couple of syllables and needs to revise their r/t.

Better tell Solent then :)

Now, something else to bear in mind. If you were to request an IFR clearance through Gatwick's local airspace for example levels will be allocated to ensure the separation requirements so, after all the identification stuff, confirmation of IFR etc the clearance might come back as 'cleared to enter CAS, fly heading 240 degrees climb to altitude 3,000ft on QNHXXXX'.

Now, with your IMC rating only qualification, what's the problem?

In the case of Gatwick I would ask for an IFR transit "not above 2500ft" (if I had only an IMCR). They should get the message from that.

[Roffa]

In the case of Gatwick I would ask for an IFR transit "not above 2500ft" (if I had only an IMCR). They should get the message from that.

They'll get the message that for some reason you don't want to go higher but they won't get the subtlety that it's because you've got an IMC rating as opposed to an IR. Very few controllers fly these days and know that the two qualifications exist. Don't be surprised if they still ask you if you could accept a higher level as higher, for them, may be better.

For IFR you'll also get a maintain level as opposed to a not above level. That maintain level is 99.9% certain to be a round number, therefore Gatwick's case 2,000ft (assuming it's terrain safe, haven't checked). The reason it probably won't be anything other than a round number is because all the other IFR stuff will be flying around at round number levels for the most part i.e. 3,000ft, 4,000ft etc and vertical separation of 1,000ft is required.

Notwithstanding all of the above and despite what everyone here seems to think, the low level CAS surrounding airfields isn't that big when it's filled with relatively fast moving and large IFR traffic so fitting in slow moving ad-hoc IFR at low levels isn't necessarily straightforward, especially when as soon as you cross the boundary into the CAS under IFR 1,000ft and/or 3nm separation is required at all times.

In my humble opinion, assuming the weather is suitable, for low level ad-hoc transits VFR is by far the best option unless it's quite quiet with other IFR traffic at the time.

[Fuji Abound]

Roffa

I think that was a very clear explanation and certainly it is my experience.

There is one other point on the same topic I would be interested in views.

Sometimes ones hears an aircraft asking for transit being told to standby, remain outside etc. From the pilots point of view this gives no indication of whether (or not) a clearance is going to be forthcoming and if it is, how long the wait might be. I have even heard and had on more than one occasion another request to standby 10 minutes later when asking how the clearance is coming along.

So my question is could controllers not respond with something more along the lines of, remain outside CAS, your onward clearance expected in x minutes, or remain outside controlled airspace, it is unlikely we are going to be able to accept you. Either would be a great deal more informative and enable a much earlier decision to be made as to whether to take up an orbit, slow down, or go around. I think it is something pilots would really appreciate, but maybe there are good reasons why it is not possible?

[IO540]

Roffa - I had the impression that controllers at London Control, and possibly Gatwick too (i.e. those who rarely if ever provide services to GA especially VFR GA) had some training to understand this.

This is because of another possibility: you can file an IFR FP, under IMCR privileges i.e. no Class A, and if you do it "right" it will not only be accepted by IFPS (which is not hard to achieve if you do it at low levels) but may also be accepted by London Control. And then you get sent into Class A pretty quick. This has happened in years past and confused the hell out of ATC.

[Captain Smithy]

A CAS transit is something that many people make a big fuss over, when in reality there is nothing to it. Follow the local procedures, do what the controller tells you (as long as it's safe), follow/report at the VRPs as instructed and don't get in the way of landing/departing traffic. If it's too busy then the controller will decline transit; go around it.

I don't think you are more or less likely to receive a transit whether you are VFR or IFR. It usually is purely based on how busy the CAS is.

In response to a previous poster I don't think ATC keeps a "black book" of unsavoury characters. However what does cheese them off somewhat is prats who don't have a clue what they are doing and fanny about in the busy CAS, e.g. folks who don't have a clue about CAS transit/local procedures, bad RT, people who request transits that take them through ILSs, people who don't follow VRPs/entry-exit lanes etc. :hmm:

Smithy

[IO540]

IMHO, regarding "black books", ATC are only human, and in this game there are certain characters that crop up regularly, in the same places, doing (or trying to do) the same thing.

[VMC-on-top]

Sometimes ones hears an aircraft asking for transit being told to standby, remain outside ..........I think it is something pilots would really appreciate, but maybe there are good reasons why it is not possible?

Fuji - agreed. I had a similar situation one evening earlier this week waiting for a re-join. So, I just did an orbit OCAS - when I would normally have been told to proceed to left / right base then call (expecting an orbit). I'm not excusing or justifying it (or pointing the finger) but it was very busy and it turns out the ATC was a trainee. Perhaps its as simple as ATC placing more importance on commercial / heavy traffic over GA or simple lack of experience?

[BackPacker]

In response to a previous poster I don't think ATC keeps a "black book" of unsavoury characters. However what does cheese them off somewhat is prats who don't have a clue what they are doing and fanny about in the busy CAS, e.g. folks who don't have a clue about CAS transit/local procedures, bad RT, people who request transits that take them through ILSs, people who don't follow VRPs/entry-exit lanes etc.

And of course, in contrast, every place also has a few regulars who do know what they're doing and where they're doing it, who are on the ball with their R/T and situational awareness, and who can be trusted to respond to the circumstances and revised clearances very well. They typically can ask for, and get, anything they want with regards to VFR CAS transits/operations. (Except for the bleeding obvious like orbiting in the ILS area, but that's something they don't even request.)

I fly out of a relatively busy controlled airport and local pilots here recognise the controllers by their voices and R/T habits, and vice versa. So if there is a black book somewhere, it's not based on callsigns but rather on other clues like R/T. After all, there may be a very experienced instructor commanding an aircraft, and one hour later an early solo student.

[englishal]

My tips for a successful CAS transit are....


Avoid the approach and departure ends of the runway and if possible ask for overhead at 90 deg to the runway. Maybe have a look at the instrument charts to see where IFR traffic is likely to be and avoid.
State your route explicitly i.e. "request zone transit from <vrp> to <vrp> via the overhead". Or "request zone transit from SAM25 to NEDUL via BIA"
If they refuse come back with "will accept alternate routing" ;)
Be sharp and don't stutter or "err err err"...


Example:

"Bournemouth Radar GABCD request zone transit"
"GABCD pass your message"
"GABCD, Rockwell Commander 112, from Bristol to Jersey IFR, 10 miles north of Bournemoth, 3000, request zone transit from SAM25 to NEDUL via BIA"

or

"Bournemouth radar, GABCD request zone transit"
"GABCD pass your message"
"GABCD, Rockwell Commander 112, from Bristol to Jersey VFR, 10 miles north of Bournemouth, 3000, request zone transit from Tarrant Rushton to Hengistbury Head via the overhead"

This is probably not strictly according to CAP124blah as I can't be bothered to state headings, pressures blah blah, but it has never failed to work (who you are, what you are and what you want).

In the second example you would get a squawk, a "not above" and probably a "report" something - like report overhead along with traffic info.

In the first you'd probably get a squawk, an altitude and when you enter the zone a "radar control service". If they vector you, just follow the vectors, but otherwise just follow your requested or cleared route. If you are limited in alt due to an IMC rating I'd ask for a "zone transit IFR at 3000" or whatever.

I'm always happy to fly with people who want to go and do stuff like this and do the radio work. One of my buddies is fairly low houred and we go off on "difficult" flights deliberately to increase his experience. With two onboard it is a great way to do it safely without busting any airspace.....

I suppose these days with AFPEx one can address the flight plan to whoever, and when I go to the channel Islands I always address it to Bournemouth and Southampton. DOn't know if it makes any difference, but I suppose you could file an IFR routing which crosses their airspace and so they are aware of you before you arrive?????

[Captain Smithy]

And of course, in contrast, every place also has a few regulars who do know what they're doing and where they're doing it, who are on the ball with their R/T and situational awareness, and who can be trusted to respond to the circumstances and revised clearances very well. They typically can ask for, and get, anything they want with regards to VFR CAS transits/operations. (Except for the bleeding obvious like orbiting in the ILS area, but that's something they don't even request.)

I agree.

My tips for a successful CAS transit are....


Avoid the approach and departure ends of the runway and if possible ask for overhead at 90 deg to the runway. Maybe have a look at the instrument charts to see where IFR traffic is likely to be and avoid.
State your route explicitly i.e. "request zone transit from <vrp> to <vrp> via the overhead". Or "request zone transit from SAM25 to NEDUL via BIA"
If they refuse come back with "will accept alternate routing" http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif
Be sharp and don't stutter or "err err err"...Again, I agree.

Smithy

[Roffa]

IO,

Roffa - I had the impression that controllers at London Control, and possibly Gatwick too (i.e. those who rarely if ever provide services to GA especially VFR GA) had some training to understand this.

It's a while since I went through the training system so I'm not 100% sure, but I don't think (nor recall) anything covering the differences between an IR and an IMC rating. It's something a controller based at an airfield may pick up from interacting with local pilots and instructors but, as regards the approach controllers at TC, unless they're one of the few remaining private pilots in ATC ranks I'd be very surprised. Remember there's no need for ATC to know the qualifications of the pilot. ATC will offer a clearance, down to the pilot to accept or otherwise. ATC needing to know or in some way policing clearances based on pilot quals is not a road to go down.

CS

I don't think you are more or less likely to receive a transit whether you are VFR or IFR. It usually is purely based on how busy the CAS is.

We'll have to agree to disagree then. With my controller's hat on it's VFR for simplicity every time.

Also, I don't think 'black books' exist except in the minds of the paranoid :)

[Tyler Durden]

I don't think you are more or less likely to receive a transit whether you are VFR or IFR. It usually is purely based on how busy the CAS is.

Would the same be true of class D other than a control zone/area, eg. the Scottish TMA?

Let's say one was going to fly from Carlisle to Prestwick at FL065. Would it be more beneficial to be VFR or IFR upon reaching the TMA boundary in such a situation, indeed would permission to enter the TMA be forthcoming at that level?


Thanks

[madlandrover]

We'll have to agree to disagree then. With my controller's hat on it's VFR for simplicity every time.

From the pilot side I'd agree that this does seem to make life easier - and I've had it confirmed by East Mids in the past (transiting in a slight hurry in a twin), when advising that I could transit IFR if it would make the ATCO's life easier to open up the whole zone rather than just the VMC bits: "Actually, I'd prefer if you could ask for VFR - it means I can push you around a little bit more". And, oddly enough, he didn't, very nice quick crossing it was too. As indeed I had a few months later, again transitting EMA on the same track, this time rather IFR in light icing, and a very quick service with only a couple of new headings.

The other thing to consider is what sort of service you'll get OCAS if IFR. In my experience so far calling up for an IFR transit tends to rather increase not only the chances of a RIS before entering, but also being asked if I'd like a service when I leave CAS. EMA again a good example, they're very slick at this. Bear in mind that ATC have no requirement to offer a service on leaving CAS, so it's nice when they do.

[Roadrunner Once]

As far as the UK is concerned below FL195, if it's not Class D then it's Class A (EGLL, London TMA, most airways), and no VFR permitted. The other classifications in use require no clearance for VFR, so it's a safe bet s/he means Class D.

[Roffa]

Post #1 said...

(assume class D)

[LEGAL TENDER]

As far as class D is concerned, VFR always wins.
I have never been denied a VFR transit when piloting, and have never denied a VFR transit when controlling. (Granted, this is Scotland, things may be different down south).

IFR is almost certain to cause more workload for ATC and less flexibility. IFR inside CAS can only be given at or above terrain safe levels, and in several areas of Scotland for example, that could be 3000ft and more. VFR can be much easier to fit beneath the IFR levels.

Radar headings... true the word "radar" doesn't feature in any R/T manual but a lot of pilots seem to like to use it as it seems to reinforce the concept this is a heading imposed by ATC rather than the heading you are following under own nav. I would say of all the quirks and slight inaccuracies of everyday R/T, this isn't the worse offender. "Report your radar heading to London / Scottish etc.." Sounds alright to me. And to the receiving unit also a reminder that it is a heading issued by another ATC unit, not, for example, for weather avoidance.

Good discussion points anyway and I hope there isn't much "fear" of ATC, especially with VFR pilots out there. A class D transit should really be a non event in terms of ATC workload. We'd always rather hear one extra question, rather than silence and misunderstanding

[IO540]

I don't get that. TC is Class A, most of which is the LTMA. One cannot get a transit of the LTMA.

The Class D bits in the UK are totally organisationally disconnected from TC, AIUI. The only time there is any connection is when a flight arrives from say FL150, passes (almost inevitably in the UK) through Class A, and going into say Bournemouth in which case TC will hand it over to Bournemouth, with the flight remaining in CAS the whole time.

Flight plans are not copied to any Class D units enroute, either.

[englishal]

Flight plans are not copied to any Class D units enroute, either.
This got me thinking though, with the advent of AFPEx whenever I file a FP I address it to anyone near my route of flight. So if flying to the Channel Islands, Bournemouth and Southampton are on my list of addressees (as I can use EGHH as an alternate). Now if one were flying IFR OCAS in the UK, say Bournemouth to Newcastle, could one address the FP to everyone on route so then they would know you are there, or doesn't it work like that?

[Roadrunner Once]

You can do that, and it would be sent to the unit concerned. However, the chances of the details of your flight actually ending up in front of the relevant approach controller are pretty slim, in my experience anyway.

IO: LTC incorporates the approach functions for the airports under the London TMA, not just the TMA itself.