When must delegated airspace be listed in the AIP?

Question

Two states can agree, through a bilateral letter of agreement, to delegate the responsibility for providing air traffic services (ATS) within a certain airspace from one state to the other. There can be numerous reasons for this. For example, a part of Scottish airspace is delegated to the Danish air navigation service provider (ANSP), because Denmark has better radar coverage within the specific area. In this area, which is within Scottish airspace, ATS is provided by the Danish ANSP.

My question is regarding the need to publish details about such airspace delegations in the national aeronautical information publications (AIP).

The previously mentioned delegated airspace is described in AIP Denmark section ENR 2.2 (Other regulated airspace). However, a part of German airspace within Hannover upper flight information region (UIR) is also delegated to Denmark, but this airspace is not shown anywhere in the AIP. To me, this seems very inconsistent, which brings me to my question: under which circumstances are states required to publish information about delegation of ATS? I am interested in references to ICAO SARPs or PANS, or, alternatively, EU regulations.

The below chart (AIP Denmark ENR 6.2 – 1) clearly indicates some delegated areas in Scottish airspace and around the border to Sweden (which I have marked with blue), but, the delegated area in Germany (which I have marked with red) is not shown.

The area is, however, shown on this "Sector Boundary Structure Chart" chart published by Eurocontrol:

I have looked in ICAO Annex 4 and Annex 15 without any luck. Appendix 1 of Annex 15 states that:

ENR 2.1 shall contain, among other things:

Detailed description of flight information regions (FIR), upper flight information regions (UIR), and terminal control areas (TMA), including:
(…)
2) identification of unit providing the service;
(…)

I usually see delegated airspaces listed in ENR 2.2, though, so they do not seem to need to be covered in ENR 2.1.

ENR 2.2 shall contain:

Where established, a detailed description of other types of regulated airspace and airspace classification.

It is not specified exactly what this includes.

Answer 1

Principles under ICAO agreements

Delegation of ATC services is contracted between ICAO members using bilateral or multilateral letters of agreement. Cases of such delegation exist typically to cover remote large airspace (e.g. Arctic agreement between multiple countries), or small areas (e.g. islands).

ICAO members are committed to fulfill the decisions of their constituent act, the Chicago Convention signed in 1944. Among the annexes to the Convention, annex 15 is related to the provision of aeronautical information services (AIS):

Annex 15 defines how an aeronautical information service shall receive and/or originate, collate or assemble, edit, format, publish/store and distribute specified aeronautical information/data. The goal is to satisfy the need for uniformity and consistency in the provision of aeronautical information/data that is required for the operational use by international civil aviation.

Impact on AIP

Annex 15 includes these generic articles:

3.1.1.2 Each Contracting State shall take all necessary measures to ensure that the aeronautical information/data it provides relating to its own territory, as well as areas in which the State is responsible for air traffic services outside its territory, is adequate, of required quality and timely. This shall include arrangements for the timely provision of required information/data to the aeronautical information service by each of the State services associated with aircraft operations.

and

3.1.7 An aeronautical information service shall receive and/or originate, collate or assemble, edit, format, publish/store and distribute aeronautical information/data concerning the entire territory of the State as well as areas in which the State is responsible for air traffic services outside its territory. Aeronautical information shall be published as an Integrated Aeronautical Information Package.

I was not able to find the decision to use AIP ENR 2.2 (other regulated airspace), but it's a matter of fact the information is found here, e.g. in the Norway AIP:

5: Delegation of Responsibility for Provision of ATS

5.1: General Denmark, Norway, Sweden and the United Kingdom have arranged through the exchange of bilateral Letters of Agreement to transfer the responsibility for provision of ATS within parts of their own area of responsibility, to their neighbouring State.

Procedures and communication within the said areas will be as if the airspace was an integral part of the FIR for which the nation mentioned is responsible.

Bidirectional scope

An effect of these articles is both the delegating and the providing states shall publish information about related areas. For example in the Spanish AIP, two cases are described.

Spain delegating to Portugal:

By agreement between Sevilla ACC and Lisboa ACC, the air traffic service is provided by Lisboa ACC within the airspace defined by [...]

Spain receiving delegation from Portugal:

By agreement between Lisboa ACC and Madrid ACC, the air traffic service is provided by Madrid ACC within the airspace defined by [...]