Holding Areas - Who separates ?

[Chilli Monster]

A scenario:

Airport A and Airport B are two ATC airports, with radar (primary and secondary) not far from each other. Airport A is outside CAS, B is inside.

A has traffic inbound to the hold, level at FL45. B calls with further trafic, inbound to themselves but on completion will be coming to the hold at A. A allocates FL55 to this traffic.

As the aircraft at FL45 aproaches to the beacon ATC A notifies B that the beacon is active at FL45, giving them the squawk of the aircraft as defined by inter unit letter of agreement. At this point the aircraft allocated FL55 is just going around at B.

Airport B, knowing the status of the hold, transfer this second aircraft to Airport A passing 2400ft, climbing to FL55 pointing straight at the beacon where there is traffic holding at FL45, with about 6 miles to run. Aircraft calls A just before standard separation is eroded and is stopped climbing just in time.

So - is anyone at fault here? Discuss

(I was going to post a poll with the following options

1: A at fault
2: B at fault
3: Both at fault
4: Neither at fault

But it doesn't seem to be working - would be interested in peoples answers to the above 4 options)

[Inverted81]

An interesting one.
I'd go with the option that both units are at fault. I assume airport B does not have their own stack? If B were aware of the situation at A, i.e, they knew an aircraft was holding at FL45, then to pass an aircraft to A in conflict is incorrect and unsafe. HOWEVER, were A aware that the second aircraft was a go around? and was co ordination incomplete that both units were not aware of the BIGGER picture?.....

Perhaps A assumed that the joining a/c was descending to FL55?
Now assuming the A hold is outside of CAS, i'm guessing both aircraft are IFR also.......

Is this a hypothetical question or as a result of an unamed incident?
I

[Chilli Monster]

Suppose for this query both aircraft are IFR trainers, and the go around at B was pre-planned and known about by A, hence the level co-ordination and allocation 20 miles before the aircraft allocated FL55 went around at B.

[PPRuNe Radar]

Don't do 'real' approach control, so with that caveat .... why did A issue a level above traffic in the hold when it obviously knew that the traffic going around was starting off below it ?? Was FL45 the minimum level available ??

That said, in the abscence of a specific co-ordination for the aircraft being in the climb, then it is incumbent for B to deliver the aircraft at the agreed level at the agreed transfer of control point.

But if you ask Standard Noise, it was probably NATS' fault somehow ;)

[av8boy]

With the caveat that all of my experience is on the other side of the pond and so, I may well be out of my depth here--coordination was poor. Certainly, that reflects on both units. That having been said however, I think the blame falls upon A for not protecting the aircraft at 45. Apparently, all it would have taken would have been one stuck mic on freq and the guy off B would have driven right through the guy in the hold. That’s some poor planning.

I guess I’m wondering about the rationale for blaming B, beyond the fact that B was a safety net for A’s oversight and failed in that regard. We all engage in poor planning from time to time, and appreciate it when somebody calls it to our attention before it goes to hell. But if I were B I’d have to assume that A had a workable plan in place for keeping these airframes apart. In this case I’d probably follow up with a call that said, “I don’t think that’s going to work… how about I put him on a heading…” (etc), but I’ve got to assume that since A knows about the guy at 45 and wants this one at 55, he or she knows something that I don’t about how this is going to work.

Again, I’ve got a responsibility to do whatever I can to keep airframes from touching each other or a non-runway part of the surface of the planet, and sometimes that means that I tell another sector or facility that I noticed something that doesn’t look right. But in a case like this, that other controller already proved to me that he or she was seeing the same thing that I was seeing. At some point I’ve got to rely on the fact that he or she has got the situation in hand. Agreed, that makes me conflicted... If I were controller B and they HAD hit, I don't know how I'd live with that either...

I’ll finish with the same disclaimer… I don’t work in your system and I don’t have a grasp of your rules. Therefore, these comments are of a general nature. But if this was my neighborhood and I was controller A, I’d be blaming myself…

Dave

Edited to say: Upon further examination (and outside discussion) it appears that I missed something in my previous analysis… As I now understand it, what was coordinated was that controller B would have the aircraft level at 55 when turning it over to controller A. That’s what controller A told controller B to do, and what controller B agreed-to. If this is the case, I officially change my position and put the blame at the feet of controller B.

[Pierre Argh]

Complicated scenario (which requires some reading through!!!)...

But, in my opinion and if I've read it correctly, B is to blame. I think A is entitled to assume that B was not going to transfer the aircraft until it's clean (i.e. level F55) as they knew that F45 was taken in the hold... but was this knowledge based on observed radar information or liaison, one hopes it would be the latter?

Possibly a strange clearance from A, if the airfields were really adjacent, expecting B to get the aircraft up to F55, through his aircraft's level, without any cooperation?

I can't help wonder if this is truly a hypothetical situation, or are you canvasing supporting opinion?

[PPRuNe Radar]

Poll now added

[Spitoon]

Without wishing to be contentious, shoud airport A really be airport F?

On to your specific question I think there are other points that need clarification. You say both units have radar - were both units providing radar services to the aircraft? I must presume that, at least, airport A was in order to spot the problem. But was the clearance issued by airport A a procedural clearance or a radar-based clearance?

If it was procedural then technically ATC A should have given the clearance to the beacon to be level FL55 at least 7 minutes (5 minutes from the holding aircraft's flight path) before the beacon.

If, on the other hand, the clearance was based on the use of radar I would expect ATC A to have ATC B put the aircraft on a 'safe' heading until ATC A was working the aircraft going to FL55.

This gets more complicated though if the aircraft are either or both IFR trainers. These flights often want to pretend they are getting a procedural service but ATC are actually giving procedural clearances to the aircraft (when they can) but providing radar separation.

In such a messy situation I don't think there's a right answer and common sense should be applied. Perhaps ATC A assumed, rather incautiously, what ATC B would do and perhaps ATC B didn't do a very sensible thing (for whatever reason). In all probability, if ATC B had radar separation from all other targets at the point they terminated their service - outside CAS - then all of the rules have been met. That just leaves the rather grey area of duty of care.

If ATC B did this knowingly - and using some justification like 'it was ok when I terminated service' I think a very quick chat between the unit bosses to get things sorted out is in order. This is the sort of thing that a LoA is supposed to cover. LoAs should get amended when it becomes clear that they need to cover additional procedures - this sounds like a good case in point.

I suppose I'd vote for 3 on the basis of the info given but may it's not so much that both units are at fault and more that both made assumptions that should have been made explicit.

[aluminium persuader]

Hey, CM

I've a pretty good idea of where A & B are. A could have been more specific & said "climb clear of the hold FL55, join level at FL55" or words to that effect, or "Hold is active at FL45. Remain clear, expect to join level at FL55". However, given the close proximity controller B, whatever he/she thought was arranged, was daft to point his traffic at traffic in the hold & climb it through. Other points though;
Exactly what was the joiner instructed to do?
Was it in/out of CAS at the time?
What service were they both under?

If the joiner had been insructed "own nav, climb FL55, remain clear of the XYZ hold", was now on a RIS, controller relaxes a little & turns attention back to his approch sequence, doesn't notice a/c take a dirty turn direct the beacon...

As with most aviation incidents, the fault doesn't lie 100% with any link in the chain although some may carry more of the burden than others. There were obviously some missed opportunities to break the chain of events leading up to a possible mid-air.

There, but for the grace... etc!

[Dave Gittins]

Seems to me - I'm just a VFR Cherokee driver - that B is at fault. He knows the "A" hold is active with IFR traffic at 4500 and has IFR traffic he needs to get to 5500 without conflict. Thus he either gives radar vectors, which he can see will enable his traffic to be above 5000 clear of the hold before joining or he asks if it can be above 5000 by "C" (between B and A.) and takes action as appropriate. Handing over traffic already in conflict to "A" must have scared the living daylights out of the poor bugger !!!

However ..... if this HAD all turned to r*t sh*t then everybody who could prospectively have stopped it from so doing (I assume that doesn't include the two aeroplanes who are presumed to be on descrete frequencies A and B) has a part to play and will have all their actions and posible monitoring actions scrutinized at the subsequent court of enquiry. Not necessary to share the blame more thinly about - but for the benefit of lessons learned.

[cat man do]

If airport A is outside CAS and has radar, what service is being provided? Airport A, by definition, should not be controlling traffic but merely providing traffic information, based on the information that Airport B is inside CAS one would have to assume that airport B is providing a controlled service and thus, based on the info provided by airport B, ensure seperation (for the a/c joining the hold) prior to leaving CAS.

Due to the fact that A had prior knowledge of the hold being occupied it remains his responsibility (being the provider of a controlled service) to ensure seperation. What also springs to mind is the fact that it appears that the 'hold' is in uncontrolled airspace and thus should not be 'controlled'. The aircraft, being in uncontrolled airspace, are subject to ATC passing 'essential traffic information' and would then climb at pilots discretion. This, of course, depends on when transfer of communication took place and who passed the traffic info.

The information passed on the scenario is too limited to make a concrete call on and is based on varios factors, namely airspace design, delegation of authority, delegation of area of responsibility, local procedures between the 2 units, knowledge of what coordination was affected, knowledge of traffic info passed etc, etc, etc.

At face value though, I would say B is responsible.

[rodan]

If airport A is outside CAS and has radar, what service is being provided? Airport A, by definition, should not be controlling traffic but merely providing traffic information.
Airport A is providing an Approach Control Service. As such, A is responsible for ensuring the separation of traffic in it's hold.

The way I see it, co-ordination with B to the effect of:

'Cleared to the hold maintaining FL55 to be level clear of my #1234 traffic holding at FL45'

would have prevented this occurence, as would allocating FL35 instead, or co-ordinating a radar heading that would keep it clear. However, I don't think B acted in a particularly neighbourly manner if the way it presented the traffic is accurately represented by the first post.

[cat man do]

Airport A is outside CAS, how then can they provide APP service? The assumption is that because they have radar they are? The presence of radar does not mean that they provide such a service. Clarification is required as to what service is being rendered by both airports/ATC. An APP unit may only provide an APP service within a CTR and/or TMA (or CTA in other places). APP may only be provided within a ATZ under certain conditions. All these classifications of airspace relate to CAS. No ATC in his/her right mind would 'control' aircraft in uncontrolled airspace, a totally different level of service is provided regardless of your qualification or equipment.

[Spitoon]

cat, your profile doesn't make it clear where you are based but, though it may be a bit surprising, in the UK we do provide control services outside controlled airspace. It's easy to say that but takes about 10 years to try to explain how and why!

[rodan]

Airport A is outside CAS, how then can they provide APP service? The assumption is that because they have radar they are? The presence of radar does not mean that they provide such a service.

From the UK MATS part 1, Section 3 (Approach Services), Chapter 1:

1.4 Outside Controlled Airspace

1.4.1 An air traffic control unit at an aerodrome outside controlled airspace (Class F and G airspace) shall provide approach control services to aircraft, as determined by the aerodrome operator and approved by the CAA, from the time and place at which:

a) arriving aircraft place themselves under the control of approach control until control is transferred to aerodrome control;

b) departing aircraft are taken over from aerodrome control until they no longer wish to receive a service or are 10 minutes flying time away from the aerodrome, whichever is the sooner;

c) overflying aircraft place themselves under the control of approach control until they are clear of the approach pattern and either no longer wish to receive a service or are 10 minutes flying time away from the aerodrome, whichever is the sooner.

It is dependant, of course on the subject a/c placing themselves under the control of the ATSU, but it seems to work fine here.

[aluminium persuader]

Seems Cat Man Doesn't!

;)

[cat man do]

Very odd set up, if you don't mind me saying. Having worked aorund the globe (not in the UK as you have guessed) the concept of providing an ATC service in uncontrolled airspace is strange. The service provision would normally be 'flight information'. Since the scenario did not specify, I naturally assumed the rules were based on the ICAO model. Well, I guess you learn something new every day.

[niknak]

Not strange at all Cat Man, in the UK it's very common and demonstrates our ability to provide the best service we can to everyone who calls.

We (regional airports) can provide a FIS, RIS (Radar Information Service) or RAS (Radar Advisory Service), the latter two of which allow us to give provide a radar service outside controlled airspace and vectors to the ILS.
Equally London Military provide the same service, and we'd be lost without them, as would the aircraft operators.

I admit that NATS area atco's with no experience of the world outside controlled airspace can be particularly vexing, often they've no idea of aircraft performance or the terms of a Radar Information or a Radar Advisory Service.

Back to the original debate, I am well aware of the two airports involved, and it shouldn't even be an issue, the ATSMs of both places deserves a kick in the nuts for not sorting it out earlier.

[cat man do]

The concept of providing an Information Service utilizing radar is not strange, the concept of providing ATC 'controlled' service in uncontrolled airspace is. I have worked in an environment where radar is used to assist ATC in providing the best service to everyone that calls. We have always been taught that you do NOT provide clearances in uncontrolled airspace as there are certain legal ramifications in the event that something goes wrong.

Do you provide 'suggested headings'? Do you clear traffic for an ILS or provide traffic info i.e. 'traffic is ....../no reported traffic, leave 4000' when ready'?

[rodan]

Do you provide 'suggested headings'? Do you clear traffic for an ILS or provide traffic info i.e. 'traffic is ....../no reported traffic, leave 4000' when ready'?
Under a radar advisory service we do indeed provide vectors and provide separation against other traffic that is participating, and avoiding action on non-participating traffic. We can also vector for 'tactical' purposes under a radar information service, whilst providing traffic information on conflicting traffic. Instrument approaches are 'cleared', as you suggest.

[cat man do]

Thanks. The next logical question I guess is, what is the difference between CAS and Un CAS? Why not extend the boundaries of CAS? Is the pilot 'obliged' to follow instructions or can he continue on his own course?

[rodan]

The difference between CAS and un-CAS is the difference between a known and unknown traffic environment. With the complex and busy airspace of the UK and the competing demands of civil (commercial and GA) and military traffic, airports that do not reach a certain level of traffic/passenger numbers are unable to justify the restrictions on other airspace users of CAS, and the system we have has developed to allow co-existence.

In the interests of brevity, I'll relate your last question to the top level of radar service available outside CAS, the Radar Advisory Service. Under a RAS, the pilot is expected to comply with all instructions as they would under radar control (level, heading, speed etc.) and the controller assumes responsibility for separating the aircraft from other traffic under their control, and for attempting to provide separation from unknown traffic. As this is an 'advisory' service, the pilot can elect not to follow instructions, and then becomes responsible for their own separation.

You can read about it all here (http://www.caa.co.uk/docs/33/CAP493PART1.PDF) in the UK MATS part 1. Section 1, Chapter 5 relates to radar services.

[Pierre Argh]

to chip on on rodan's point...

Unregulated airspace (Class F&G... outside CAS) is an unknown traffic environment. The ATS provided in the UK in such airspace is advisory and does not guarantee separation from other traffic... although ATC will attempt to separate (Most airspace users know this... although I wonder about some of the International flights we get into our airfield that have to transit a chunk of Class G to reach us?)... It is not a perfect system, but there is massive competition/resistance to establishing more regulated airspace and restricting the "rights" of aviationists of all persuasions... and there are plans to increase the amount of "known traffic" airspace, but it's not there yet!

(Sorry if this is repeating what has already been said?)

[DFC]

B is at fault from an inter unit coordination viewpoint. However the CAA is more at fault from an airspace and regulatory point of view.

Regardless of the situation, unit A agreed to accept traffic from adjacent unit B at FL55.

In the normal situation it is the responsibility of unit B to ensure that the aircraft complies with the coordination agreed before it leaves their area of responsibility.

In my view it is an open and shut case on an inter unit basis. However the CAA is largely at fault and I believe that this example highlights failings in the regulator.

This situation is inherently unsafe in design exactly because there is no controlled airspace.

The controller at B can not clear an aircraft any further than the boundary of controlled airspace i.e. "abc123 cleared to leave controlled airspace on track AB climbing to FL55" or ABC123 cleared to leave controlled airspace to the west climbing to FL55"

Overall, the controller at B has no control over the flight after the airspace boundary.

One would have to investigate the inter-unit agreements and also the demed separations in force between the two holding areas and inbound/outbound routes as well as the RMAs.

For example should the controller at B put the aircraft back into his/her hold until it was level at FL55 or at least kept it within their controlled airspace? If so where is that written down.

If the border between the two unit's area of responsibility is a distance from the controlled airspace boundary the the following clearance would both comply with the CAAs requirement only to clear aircraft to the boundary of controlled airspace and clearly tell the pilot that they are expected to be at FL55 for the next unit.

"ABC123 cleared to leave controlled airspace to the North climbing to FL55. Unit A will accept you level at FL55".

Unfortunately, that CAA approved clearance can result in this situation we are talking about.

If however the inter unit boundary is the edge of controlled airspace then it is easier to define and the clearance is less open to dangerous errors;

"ABC123 leave controlled airspace to the north climb FL55 level by the zone boundary."

Of course if the airfields are very close then the holding area from airfield A may enter the controlled airspace for airfield B

Then of course we have the old problem of the pilot havign left controlled airspace deciding to do some general handling before the next holding exercise. Being outside controlled airspace, that pilot can turn off the radio, play round from the MSA to FL whatever and on completion level the aircraft at FL55 and tune in airfield A and report inbound to the beacon at FL55.

Not to mention that joker G-WXYZ could decide to do a few holds at airfield As beacon at FL50! in IMC with no radio and no transponder at all.

Overall, everyone must agree that whatever the cause the effect is a dangerous situation. It is incumbent on the CAA as the regulator to act to prevent dangerous situations. I believe that simple Class E airspace round such airfields would improve the safety situation drastically without impinging on any VFR pilot's right to go as they please in VMC.

Regards,

DFC

[Chilli Monster]

Well - we've just had the same happen (in the past few minutes) and the unit was told "Hold active at FL**, join LEVEL FL** +1000ft" (sanitised due to possible reporting action)

Anyone want to change their opinion?

[Pierre Argh]

DFC
I don't agree... it's nothing to do with the CAA or Class E airspace (although that might be a future solution... but don't hold your breath?)
the controller at B has no control over the flight after the airspace boundary
B may be unable to issue mandatory instructions outside CAS... but still has a responsibility for that flight under ATSORA. The key phrase in ChilliMonster's original post is "pointing straight at" the beacon... it seems B has released the aircraft, following liaison, into known confliction and therefore failed in their duty of care.

[Standard Noise]

PPRuNe Radar - I've taken some time and read a few books, but after ten days I've had to admit defeat, I just can't find a way to blame this one on NATS. Sorry to disappoint my man, but there you go. Normal service will resume shortly.:ok:

Now, since this is hypothetical, and the two units are obviously fictional;) , then I will say this, maybe the co-ordination by both hypothetical ATCO's could have been better to achieve the collective aim.
Possibly giving a heading away from the O bviously F ictional hold would be a good idea in these hypothetical situations, or requesting (hypothetically, of course) that ATCO A will accept the trainer once level at FL55.
However, and I'm no different in these hypothetical situations from time to time as you well know Chilli, maybe ATCO B should have had the hypothetical gumption to not send the trainer to the O bviouslyF ictional hold in the full hypothetical knowledge that another hypothetical flying machine was already, hypothetically speaking, holding at a conflicting level.

Who knows, I'm only an interested obsever on this one, hypothetically speaking.:cool:

[DFC]

Pierre,

The whole idea of safety is to get rid of as many uncertainties as possible. If the CAA had either put the appropriate airspace in place or prevented such operations then we would not be having the debate about a series of what if's.

Even you say - "B may be unable to issue mandatory instructions outside CAS"

It is that "may be" and all the other may be's in the situation that could reduce the level of safety. Thus the professionals at the sharp end are having concerns.

Regards,

DFC

[Standard Noise]

Hypothetically speaking, these flights participate in a particular type of service outside CAS and therefore are 'under the control' of ATCO B, unless the a/c commander informs ATCO B otherwise.

Trust me.

[Pierre Argh]

I am finding it difficult to continue with this thread... the hypothetical is merging with real-life... if these events are actually happening then I don't think PPRuNe is the best way to find a safe solution? We should all have SMS systems in place, this is a potential accident (hypothetical or not)... run it through the SMS?

DFC... you last past was so full "what-ifs and maybes" that I haven't a clue what you're talking about?... but I'd be quite interested in who you mean by "the professionals at the sharp end"?