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Is it the CTR or the TMA?

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Is it the CTR or the TMA?

Old 14th Nov 2019, 17:27
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Is it the CTR or the TMA?

Hi all,

Is there an ICAO or EASA rule which stipulates which airspace prevails when a CTR is defined as being part of a TMA?
For example, the Maastricht CTR is defined as being from the surface to 3.000ft AMSL and the TMA from 1.500ft AMSL to FL95, and for a big part they are part of the same geographical area (the TMA does not exclude the CTR in its definition).

So, is the part between 1.500ft and 3.000ft AMSL in the CTR or in the TMA? Whose area of responsibility is this airspace?
I'm looking for a general rule, or perhaps something in the Dutch AIP which I am missing. The same situation occurs in other European countries too (at least Austria, Greece and Germany).

Thanks for your help!
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Old 14th Nov 2019, 19:31
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A CTR is normally Class D airspace but a TMA is usually B or C and A in the UK.
As the rules for entering these latter 3 types of airspace are stricter, they take priority
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Old 14th Nov 2019, 22:06
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Thanks for your reply, chevvron.

To make it a bit more complicated however, I will take the example of the LOWS CTR/TMA, both of which are the same class of airspace (D).

CTR: Surface - 7.000ft AMSL, class D
Controlling unit: Salzburg Tower

TMA: 1.000ft AGL - 3.500ft AMSL, class E
3.500ft AMSL - FL195, class D
Controlling unit: Salzburg Radar (Approach)

Whose airspace is the slice between 3.500ft and 7.000ft ?
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Old 14th Nov 2019, 22:19
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You can infer, a bit, of what to expect from Annex 11 by looking at the definitions of control zones, control area and terminal control areas (which for practical purposes equate to TMAs, although I can't think of anywhere it says this). It then goes on to recommend that the name of the ATS unit which provides area services should be name after a nearby town or city or geographic feature and an aerodrome or approach unit should be named after the aerodrome at which it is located.

It also says that responsibility for the control of a given block of airspace is to be given to a single air traffic control unit. But it doesn't say which one in any particular situation, although it does make provision for responsibility for blocks of airspace to be delegated from one unit to another under agreed procedures..

So the rules are not written in a way to give a simple answer to your question about which ATC unit is responsible for any particular bit of airspace. The old ICAO rules work well in principle and have generally served us well in the past but with currently available technologies it it quite possible for services in one bit of airspace to be provided from an ATC unit some way away and having no real association with the place where the service is provided and I have heard discussions about whether it's necessary for a pilot to know or care about such things. This has been the case for many area units for a long time, it's not a problem to talk to London or Paris Control when the aircraft is nowhere near those cities, for example, but it's not so straightforward if there's one approach unit that provides services for a number of aerodromes. I'm rambling a bit on this but it's really just to underline the fact that the name of the unit does not necessarily relate to where the controllers are sitting.

Looking at your example at EHBK, I would imagine the reason that the CTR extends up into the TMA is that if the airport/ATC unit is closed (which is regularly the case at EHBK) the CTR doesn't exist. So, is the airspace TMA or CTR - in my view, it's both. I would guess that when EHBK is open, the airport-based ATC unit looks after the CTR and maybe even a bit of the TMA, to enable them to provide services to aircraft going in and out of the airport. When the airport is closed, the whoever controls the TMA takes control of that bit of the CTR which is in the TMA. Exactly who looks after any aircraft that are transiting the CTR (e.g. flying across the airport at 2000ft) when the airport is open, along with details of how the airspace is operated on a day-to-day basis will be set out in agreements between all the interested parties. A quick look at the NL AIP highlights that nothing in that location is going to be easy because the CTR sits in three different FIRs.

Hope that makes some sense and helps answer the questions.
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Old 15th Nov 2019, 09:39
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Thank you both for your answers.

I understand that services can be provided remotely, and I agree that the name of the controlling unit can be completely unrelated to its location or the location of the airspace controlled (Frisbee tower controls Geilenkirchen airport).

Would the delegation of airspace be included only in the units' LoAs with each other? Should it not also be included in the AIP?
Let's say that a VFR flight wants to cross the CTR/TMA at 2.000ft from the west (Belgian class G airspace) to the east. Should the pilot contact EHBK TWR or EHBK APP?

To eliminate the difference in airspace classification, we could look at LOWS. There, both CTR and TMA are class D (between 3.500ft and 7.000ft) and the CTR is again within the TMA.

I had a look at Annex 11, and the only related thing which I found was this:
2.9.5.3 If a control zone is located within the lateral limits of a control area, it shall extend upwards from the surface of the earth to at least the lower limit of the control area.
Note. An upper limit higher than the lower limit of the overlying control area may be established when desired.

So while it says that such a structure is possible, it does not resolve the ambiguity of the responsibility in the common airspace.
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Old 16th Nov 2019, 16:57
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A CTR is normally Class D airspace but a TMA is usually B or C and A in the UK.
As the rules for entering these latter 3 types of airspace are stricter, they take priority
chevvron - can you quote chapter and verse for that statement?

Actually, I would have thought that the formal notification of the airspace in the AIP would/should make it clear, even if it is hard work going through all the co-ordinates and "except that airspace contained within.." etc. After all, that is the definitive authority.

2 s
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Old 17th Nov 2019, 19:20
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A3623, I wrote a longer answer but when I clicked submit PPRuNe lost it all! But here's a precis.....

I would expect basic info about delegation of airspace to be in the AIP, probably limited to who to call at different times of the day. Publishing the details in a LoA in the AIP probably wouldn't make a lot of sense to anyone unless they know all the 'normal' procedures as well.

I don't know enough about the local airspace and procedures to give much of an answer on the 2000ft VFR example, but here's my best guess. Coming from the west the first call would be to Maastricht tower and I would expect it to be transferred to Maastricht approach when it comes to the CTR boundary and it's going north or south into TMA1 (I'll take your word for it that it's class G on the BE side, just as I don't know what's on the DE side which would affect what might happen if it leaves the CTR into DE airspace).

The differences in airspace class undoubtedly some things more complex, as does the fact that there's more than one FIR involved. But these things affect what an aircraft might be able to do in different weather conditions rather than who operates the airspace.

When I had a quick skim of annex 11 before my earlier answer, I found four or five paras which may be relevant but I can't recall which the were - there is no clear answer to you question in the document and, at best, all I was trying to do was put together a bit of an argument that would fit your question.

Bottom line, though, the controlling authority for the CTR looks to be Maastricht tower and for the TMA it's Maastricht approach. At night when the airport is closed the CTR either does not exist (depends on national law) and the airspace above 1500ft simply becomes TMA (instead of CTR/TMA), or that portion of the CTR 1500ft and above is delegated to approach.

Still don't know if that helps at all......
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Old 17th Nov 2019, 20:45
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Yes, the Tower is the unit responsible for the CTR and Approach is responsible for the TMA.

The situation at night is a bit clearer:
Originally Posted by EHAM/A1497/19
Outside operating hours of Maastricht aachen airport(as published in the AIP Netherlands), the Maastricht CTR will change status to radio mandatory zone (RMZ).
The airspace classification within the RMZ will correspond to the surrounding airspace, GND-1500FT AMSL class G, 1500FT AMSL-3000FT AMSL class D. Air traffic service will be provided as defined for that airspace. Before entering the RMZ contact Amsterdam info on the beek tower frequency 119.480. The AIP Netherlands will be amended accordingly in due time.
REF AIP ENR 2.2.
So basically, the CTR transforms into an RMZ at and below 1.500ft AMSL and above it is swallowed by the TMA. Dutch Mil is the controlling unit of the Maastricht TMA 1 outside the Tower's operating hours.

I was also expecting something along the lines of "The TMA is this except the airspace contained in the CTR", either in the definition of the TMA itself, or as a general rule, but I guess it's considered obvious!
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Old 18th Nov 2019, 13:14
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Originally Posted by 2 sheds View Post
chevvron - can you quote chapter and verse for that statement?

Actually, I would have thought that the formal notification of the airspace in the AIP would/should make it clear, even if it is hard work going through all the co-ordinates and "except that airspace contained within.." etc. After all, that is the definitive authority.

2 s
No I can't; all I can say is that once upon a time before it was re-organised in about 1976, the LTMA was the equivalent of Class E below 5,000ft irrespective of its base level which in some places was as low as 1,500ft (eg between the Heathrow and Gatwick CTRs) whilst the Heathrow CTR was 'Rule 22' (mandatory IFR) from SFC to FL110
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Old 22nd Nov 2019, 04:59
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Originally Posted by A3623 View Post
Yes, the Tower is the unit responsible for the CTR and Approach is responsible for the TMA.

The situation at night is a bit clearer:

So basically, the CTR transforms into an RMZ at and below 1.500ft AMSL and above it is swallowed by the TMA. Dutch Mil is the controlling unit of the Maastricht TMA 1 outside the Tower's operating hours.

I was also expecting something along the lines of "The TMA is this except the airspace contained in the CTR", either in the definition of the TMA itself, or as a general rule, but I guess it's considered obvious!
The truth of the matter is that there is a huge variation of arrangements within and between various States. You really need to look at each location in the relevant AIP on a case by case basis to work out airspace classifications/configurations/which unit manages it/and when.
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