OPINION OF ADVOCATE GENERAL
CAMPOS SÁNCHEZ-BORDONA
delivered on 12 February 2026 (1)
Case C‑857/24
daa plc, formerly Dublin Airport Authority plc,
Aer Lingus Ltd,
Ryanair Designated Activity Company,
Air Transport Association of America Inc., trading as Airlines for America,
Delta Air Lines Inc.,
JetBlue Airways Corporation,
United Airlines Inc.,
Emerald Airlines Ireland Ltd
v
Irish Aviation Authority,
Airport Coordination Ltd
(Request for a preliminary ruling from the High Court (Ireland))
( Reference for a preliminary ruling – Air transport – Regulation (EEC) No 95/93 – Article 2(m) and Article 6 – Coordination parameters – Relevant technical, operational and environmental constraints – Limitation of the annual number of air passengers – Article 8 – Allocation of slots – Restriction on the allocation of historical slots – Property right – Power of the airport managing body to order the temporary closure of the airport in order to comply with the limitation on the annual number of passengers – Admissibility – Competence of the airport managing body )
1.        In 2007 and 2008, An Bord Pleanála (Planning Board, Ireland) (2) imposed an annual limit of 32 million passengers as a condition of authorising the expansion of Terminals 1 and 2 at Dublin Airport (Ireland).
2.        When drawing up the ‘coordination parameters’ that would apply at Dublin Airport during the winter of 2024 and the summer of 2025, the Irish Aviation Authority (IAA) (3) adopted certain measures to ensure that the 32 million passenger cap would not be exceeded.
3.        The air carriers concerned argue, in essence, that:
–        The maximum of 32 million passengers per annum cannot be classified as a ‘technical, operational or environmental constraint’ for the purposes of drawing up coordination parameters in accordance with Article 6(1) of Regulation (EEC) No 95/93. (4)
–        As a grandfather right enjoyed by air carriers, the allocation of ‘historical slots’ cannot be compromised.
4.        The referring court refers its doubts on these two points to the Court of Justice and, in addition, wishes to ascertain whether, in order to comply with the annual passenger limit, the airport managing body is empowered to order the temporary closure of the airport.
I.      Legal framework. European Union law. Regulation No 95/93
5.        Article 2 (‘Definitions’) states:
‘For the purpose of this Regulation:
(a)      “slot” shall mean the permission given by a coordinator in accordance with this regulation to use the full range of airport infrastructure necessary to operate an air service at a coordinated airport on a specific date and time for the purpose of landing or take-off as allocated by a coordinator in accordance with this regulation;
…
(g)      “coordinated airport” shall mean any airport where, in order to land or take off, it is necessary for an air carrier or any other aircraft operator to have been allocated a slot by a coordinator, with the exception of State flights, emergency landings and humanitarian flights;
…
(m)      “coordination parameters” shall mean the expression in operational terms of all the capacity available for slot allocation at an airport during each coordination period, reflecting all technical, operational and environmental factors that affect the performance of the airport infrastructure and its different sub-systems;
…’
6.        Article 3 (‘Conditions for airport coordination’) states:
‘1.      (a)      A Member State shall be under no obligation to designate any airport as schedules facilitated or coordinated save in accordance with the provisions of this article.
…
5.      Where capacity problems occur for at least one scheduling period, the Member State shall ensure that the airport is designated as coordinated for the relevant periods only if:
(a)      the shortfall is of such a serious nature that significant delays cannot be avoided at the airport, and
(b)      there are no possibilities of resolving these problems in the short term.
…’
7.        Article 4 (‘The schedules facilitator and the coordinator’) provides:
‘1.      The Member State responsible for a … coordinated airport shall ensure the appointment of a qualified natural or legal person as … airport coordinator …
…
5.      The coordinator shall be the sole person responsible for the allocation of slots. He shall allocate the slots in accordance with the provisions of this regulation …
…’
8.        Article 6 (‘Coordination parameters’) provides:
‘1.      At a coordinated airport the Member State responsible shall ensure the determination of the parameters for slot allocation twice yearly, while taking account of all relevant technical, operational and environmental constraints as well as any changes thereto.
This exercise shall be based on an objective analysis of the possibilities of accommodating the air traffic, taking into account the different types of traffic at the airport, the airspace congestion likely to occur during the coordination period and the capacity situation.
The parameters shall be communicated to the airport coordinator in good time before the initial slot allocation takes place for the purpose of scheduling conferences.
…’
9.        Article 8 (‘Process of slot allocation’) reads:
‘1.      Series of slots are allocated from the slot pool to applicant carriers as permissions to use the airport infrastructure for the purpose of landing or take-off for the scheduling period for which they are requested, at the expiry of which they have to be returned to the slot pool as set up according to the provisions of Article 10.
2.      Without prejudice to Articles 7, 8a and
9, Article 10(1) and Article 14, paragraph 1 of this Article shall not apply when the following conditions are satisfied:
–      a series of slots has been used by an air carrier for the operation of scheduled and programmed non-scheduled air services, and
–      that air carrier can demonstrate to the satisfaction of the coordinator that the series of slots in question has been operated, as cleared by the coordinator, by that air carrier for at least 80% of the time during the scheduling period for which it has been allocated.
In such case that series of slots shall entitle the air carrier concerned to the same series of slots in the next equivalent scheduling period, if requested by that air carrier within the time limit referred to in Article 7(1).
…
3.      Without prejudice to Article 10(2), in a situation where all slot requests cannot be accommodated to the satisfaction of the air carriers concerned, preference shall be given to commercial air services and in particular to scheduled services and programmed non-scheduled air services. In the case of competing requests within the same category of services, priority shall be given for year round operations.
…
5.      The coordinator shall also take into account additional rules and guidelines established by the air transport industry world-wide or Community-wide as well as local guidelines proposed by the coordination committee and approved by the Member State or any other competent body responsible for the airport in question, provided that such rules and guidelines do not affect the independent status of the coordinator, comply with Community law and aim at improving the efficient use of airport capacity. These rules shall be communicated by the Member State in question to the Commission.
…’
10.      Article 8a (‘Slot mobility’) governs the conditions for the transfer and exchange of slots and requires that any such transfers and exchanges are to be notified to the coordinator and are not to take effect prior to the express confirmation by the coordinator.
11.      In the light of Article 8b (‘Exclusion of compensation claims’), ‘the entitlement to series of slots referred to in Article 8(2) shall not give rise to any claims for compensation in respect of any limitation, restriction or elimination thereof imposed under Community law …’.
12.      Article 10 contains the rules governing the ‘slot pool’.
II.    Facts, dispute and questions referred for a preliminary ruling
13.      Dublin Airport has been designated as a ‘coordinated airport’ for the purposes of Regulation No 95/93 (5) since 2007.
14.      On 29 August 2007, An Bord Pleanála granted consent for the construction of Phase 1 of the development project for a new terminal (Terminal 2) at Dublin Airport.
15.      The
consent provided that ‘the combined capacity of Terminal 2 as permitted together with Terminal 1 shall not exceed 32 million passengers per annum (‘the 32 mppa condition’) unless otherwise authorised by a further grant of consent’.
16.      Prior to the grant of consent, An Bord Pleanála carried out an environmental impact assessment pursuant to Directive 85/337/EEC. (6)
17.      On 10 January 2008, An Bord Pleanála granted consent for the Terminal 1 extension project, which was subject to the same 32 mppa condition as that included in the consent for Terminal 2.
18.      Although no environmental impact statement was submitted with the application for the Terminal 1 extension consent, An Bord Pleanála carried out an assessment of the environmental effects prior to granting consent.
19.      There were
two reasons for imposing the 32 mppa condition for Terminals 1 and 2:
–        The policies and objectives of the ‘Dublin Airport Local Area Plan 2006’ (7) took into account the fact that Terminals 1 and 2 are situated in the eastern part of Dublin Airport and that the 2006 Plan proposed the construction of a third terminal in the western part. So as not to jeopardise balanced development between the existing eastern campus and the proposed western campus, having regard to the fact that the overall capacity of the airport was at that time considered to be in the region of 45 million passengers per year, it was decided to limit the combined capacity of Terminals 1 and 2.
–        The second reason referred to ‘capacity constraints (transport) at the eastern campus’.
20.      In 2024, passenger forecasts carried out by the Dublin Airport managing body (8) indicated that, for the first time, the limit imposed under the 32 mppa
condition could be reached or, even, exceeded.
21.      In that context:
–        On 7 May 2024, the IAA published its Final Decision on Winter 2024 Coordination Parameters at Dublin Airport. (9) That decision states that, ‘to appropriately take account of these planning conditions, [the IAA has] decided to implement a seat capacity limit of 14.4 million seats for the W24 season’. Accordingly, in that season the IAA imposed an air traffic movement seat cap of 14 405 737 passengers during the period commencing on 27 October 2024 and ending on 29 March 2025. (10) Although that restriction had an impact on the slot pool and on changes in service to Dublin by US carriers, it did not have the result that the coordination parameters for winter 2024 were insufficient to accommodate all the slots to which air carriers would be entitled under Article 8(2) of Regulation No 95/93 (‘historical slots’).
–        On 10 October 2024, the IAA published its Final Decision on Summer 2025 Coordination Parameters at Dublin Airport. (11) That decision states that, ‘to take account of the constraint represented by certain planning conditions which limit the combined capacity of Terminal 1 and Terminal 2 at Dublin Airport to 32 million passengers per annum …, [the IAA has] included a coordination parameter in the form of a seasonal seat cap of 25.2 million seats’. As a result of the application of that cap, the airport coordinator (12) was unable to accommodate all the slot requests from air carriers or to allocate certain historical slots.
22.      The Dublin Airport managing body and a number of air carriers lodged appeals before the High Court (Ireland) against both the winter 2024 decision and the summer 2025 decision. (13)
23.      On 4 November 2024, the High Court provisionally suspended implementation of the summer 2025 decision. As a result, the Dublin Airport coordinator was able to allocate to air carriers all their historical slots for the summer 2025 season.
24.      The arguments of the applicant air carriers
focus on two areas: (i) they question the legality of the IAA’s course of action in setting the coordination parameters on the basis of the 32 mppa condition; and (ii) they claim that their grandfather rights (historical slots) are protected under Regulation No 95/93 and the Charter of Fundamental Rights of the European Union (‘the Charter’).
25.      In those circumstances the High Court referred the following questions to the Court of Justice (14) for a preliminary ruling:
‘(1)      Can a national competent authority undertaking the exercise of determining the parameters for slot allocation at a coordinated airport under Article 6(1) of Regulation
[No 95/93]
(as amended) take into account development consents granted by the relevant planning authority under the national planning code in respect of that airport which impose conditions providing inter alia that the “combined capacity” of the airport terminals shall not exceed a certain annual limit of passengers, and in respect of which the stated reason for the imposition of the conditions was “Having regard to the policies and objectives of the Dublin Airport Local Area Plan and the capacity constraints (transportation) at the eastern campus”? Are such conditions a “relevant technical, operational or environmental constraint” within the meaning of Article 6(1)? Do they form part of the objective analysis of the capacity situation at the airport for the purposes of Article 6(1)?
(2)      If the answer to question 1 is yes, does Article 6(1) of Regulation
[No 95/93], and in so far as relevant Articles 16 and
17 of the [Charter], permit Member States to make a determination of the parameters for slot allocation at a coordinated airport for a particular scheduling period which results in the non-allocation of some series of slots (or certain components thereof) to which air carriers would otherwise be entitled in accordance with the terms of Article 8(2)?
(3)      If this arises for consideration strictly as a result of the Court’s answers to questions 1 and
2, does [Regulation No 95/93] prohibit airport management bodies within the meaning of [Regulation No 95/93] from taking unilateral action to close the airport for a period of time, for the purpose of preventing the operation of slots which have been allocated by the airport coordinator so as to avoid a breach of an annual limit of passengers of the type mentioned in Question 1?’
III. Procedure before the Court of Justice
26.      The request for a preliminary ruling was registered at the Court of Justice on 11 December 2024.
27.      Written observations have been lodged by the Dublin Airport managing body, Aer Lingus Ltd, Ryanair Designated Activity Company, Air Transport Association of America Inc. and others, the IAA, the Netherlands Government and the European Commission.
28.      In the light of the content of the request for a preliminary ruling, and after being informed of the existence of a ruling of 11 December 2024 (15) which had not been included in the case file, the Court asked the referring court to provide that document, which it did. The document was made available to the parties and the interveners in the preliminary ruling proceedings before the hearing.
29.      The Dublin Airport managing body, Aer Lingus Ltd, Ryanair Designated Activity Company, Air Transport Association of America Inc. and others, the IAA, Ireland and the Commission participated in the hearing held on 25 November 2025.
IV.    Assessment
A.      Airport organisation and slots
30.      The IATA Guidelines (16) establish three levels of airport depending on the congestion they experience. Each level has a different system for allocating infrastructure capacity for landing and take-off among the airlines using the airport in question:
–        Level 1. No allocation of slots or coordination is required.
–        Level 2. Schedules are recommended by a ‘facilitator’.
–        Level 3.
Slots must be allocated by a ‘coordinator’.
31.      EU law does not regulate the allocation of slots at Level 1 airports (described by Regulation No 95/93 as having ‘no particular designation status’), which are governed by the ordinary civil aviation legislation of each country. (17)
32.      Regulation No 95/93 lays down the rules applicable within the European Union to the allocation of slots at Level 3 airports (‘coordinated airports’) and voluntary cooperation as regards access to the infrastructure of Level 2 airports (‘schedules facilitated airports’).
33.      Article 3 of Regulation No 95/93 sets out the conditions for airport coordination:
–        Paragraph 1 imposes an obligation to designate an airport as coordinated where the conditions laid down in that article are met.
–        Paragraph 3 provides that a Member State must carry out a thorough analysis of an airport’s capacity on a request from ‘air carriers representing more than half of the operations at [the] airport or from the managing body of the airport where either considers capacity is insufficient for actual or planned operations at certain periods’.
–        Paragraph 5 provides that capacity problems (shortfalls) may lead to the designation of an airport as coordinated.
34.      The concept of a slot is defined in Article 2(a) of Regulation No 95/93 as ‘the permission given by a coordinator in accordance with this Regulation to use the full range of airport infrastructure necessary to operate an air service at a coordinated airport on a specific date and time for the purpose of landing or take-off as allocated by a coordinator in accordance with this Regulation’.
35.      Article 2(m) of Regulation No 95/93 defines ‘coordination parameters’ as ‘the expression in operational terms of all the capacity available for slot allocation at an airport during each coordination period, reflecting all technical, operational and environmental factors that affect the performance of the airport infrastructure and its different sub-systems’.
36.      At a coordinated airport, the Member State must ensure, in accordance with Article 6(1) of Regulation No 95/93, ‘the determination of the parameters for slot allocation twice yearly, while taking account of all relevant technical, operational and environmental constraints as well as any changes thereto’.
37.      Dublin Airport, a coordinated airport since 2007, is subject to the 32 mppa condition, which was included in the development consent granted previously by An Bord Pleanála for the extension of its terminals. (18) That condition had not had an impact on the coordination parameters for the allocation of slots until 2024, when the IAA took it into consideration when determining the parameters applicable to the winter 2024 and summer 2025 seasons.
38.      Although the two terminals can physically accommodate more than 32 million passengers per annum without additional infrastructure works, the fact that that limit has been set means that, if it is breached, the airport managing body can be penalised.
B.      First question referred for a preliminary ruling
39.      The referring court asks the Court of Justice to interpret Article 6(1) of Regulation No 95/93. It wishes to ascertain whether, in accordance with that provision:
–        The coordination parameters for the allocation of slots may take into account development consents granted by the planning authority which impose an annual passenger limit.
–        The 32 mppa condition may be classified as a relevant technical, operational or environmental constraint for the purposes of determining the coordination parameters.
–        That constraint forms part of the objective analysis of the capacity situation at the airport.
40.      According to the ruling attached to the request for a preliminary ruling, in order to decide whether the IAA was entitled to have regard to the planning conditions attaching to developments at Terminals 1 and 2 at Dublin Airport (in particular the 32 mppa condition), it must be determined: (a) what is meant by ‘relevant constraint’ for the purposes of determining coordination parameters; and (b) what is meant when Regulation No 95/93 ‘refers to the determination of coordination parameters being based on “objective analysis of the possibilities of accommodating the air traffic, taking into account the different types of traffic at the airport, the airspace congestion likely to occur during the coordination period and the capacity situation”’. (19)
1.      Arguments of the parties and interveners in the preliminary ruling proceedings
41.      The IAA claims that the 32 mppa condition may be regarded as one of the ‘relevant technical, operational and environmental constraints’ used to determine the coordination parameters. Those parameters must reflect the capacity actually available, regard being had to existing limitations:
capacity may not be set at a level higher than that actually feasible or legally possible.
42.      The Dublin Airport managing body concurs with the IAA when it states that the conditions imposed in the development consent form part of the objective analysis of the capacity situation and constitute relevant constraints within the meaning of Article 6(1) of Regulation No 95/93. (20)
43.      Ireland,
the Netherlands Government and the Commission also argue in favour of an affirmative answer to the first question referred for a preliminary ruling.
44.      The air carriers reject the IAA’s line of argument on the basis of the following (summarised) arguments:
–        A planning condition does not fall within the scope of the list of constraints set out in Article 6(1) of Regulation No 95/93.
–        The expression ‘technical constraints’, as it is usually understood, concerns the technical capacity of the equipment or facilities involved in the handling of aircraft, passengers and baggage.
–        The expression ‘operational constraints’ covers factors such as taxiway configuration, aircraft towing and runway operating modes.
–        There are no ‘environmental constraints’ in this case because the reasons for the limitation were political, it being a matter of facilitating the western expansion of Dublin Airport and not jeopardising the development of a third terminal in that area.
–        The limitation on the number of passengers does not reflect the airport’s ‘capacity’ or the physical or technical limitations of its infrastructure. There is some confusion between ‘passenger flow’ and ‘capacity’ at the airport. ‘Flow’ refers to the number of passengers actually using the terminals, whereas ‘capacity’ is the maximum number of passengers which the terminals can accommodate.
–        As the capacity of the terminals at Dublin Airport exceeds 32 million passengers per annum, the 32 mppa condition does not constitute a limit on the ‘capacity’ of those terminals but is linked to passenger ‘flow’.
2.      Assessment
45.      Discussion in this case features two opposing understandings of the meaning of the expression ‘relevant constraints’. While some favour a purely physical interpretation of that term, others argue that it should include ‘legal’ constraints such as that represented by the 32 mppa condition.
46.      Regulation No 95/93 does not spell out the meaning of ‘relevant technical, operational or environmental constraints’. The twofold reference, in Article 2(m) and Article 6(1), to the requirement that the coordination parameters are to be set with regard to ‘all’ those constraints (factors) (21) suggests that there is a certain breadth to the semantic field of the expression, but does not provide any further pointers for its interpretation.
47.      As the Netherlands Government notes, (22) the interpretation of Regulation No 95/93 must take into account the fact that the capacity of a coordinated airport is the central element in the process of allocating slots, which are granted precisely in order to achieve the most efficient use of airport capacity. (23)
48.      Article 6(1) of Regulation No 95/93 provides that the exercise of determining the coordination parameters ‘shall be based on an objective analysis of the possibilities of accommodating the air traffic, taking into account … the capacity situation’.
49.      The process of allocating slots at a coordinated airport must therefore be carried out with an assessment of all the relevant technical, operational and environmental factors affecting airport capacity.
50.      In my view, those factors are not only physical or material factors:
capacity analysis cannot disregard the (legal) constraints imposed by the rules which, directly or indirectly, affect the use of the airport.
51.      From that point of view, I concur with the Netherlands Government (24) that the term ‘relevant’ as used in Article 6(1) of Regulation No 95/93 cannot be interpreted as a restriction. On the contrary, it reflects a broad interpretation of the constraints that are to govern the slot allocation process.
52.      Contrary to the arguments put forward by the applicant carriers, I see no reason why the limitation inherent in the obligation to comply with the 32 mppa condition should not be classified as one of the operational constraints. That obligation is binding on all public authorities to the extent that any failure to comply with it may entail penalising, including criminal, consequences. (25)
53.      As the Dublin Airport managing body states, (26) disregarding the 32 mppa condition would mean either that air carriers would have to be allocated slots even where they cannot in practice operate them because they would be in breach of the development consent issued by the planning
authority, or that the carriers would be considered to be authorised to operate slots in disregard of the conditions imposed by the aforementioned development consent.
54.      As I have already stated, the exercise of determining the coordination parameters must be based on an objective analysis of, among other factors, the airport’s capacity. The 32 mppa condition is an element which, with binding effect on all concerned, affects, precisely, the operational capacity of the airport.
55.      That constraint, which imposes a maximum number of passengers per annum on the airport does not, in my opinion, cease to be ‘operational’ by virtue of the fact that it is issued by a State planning authority. Irrespective of its origin, (27) what is decisive is that it restricts airport ‘operational capacity’.
56.      I also concur with the line of argument put forward by the IAA (28) to oppose the submissions of certain air carriers attempting to dissociate ‘airport capacity’ from ‘passenger flow’.
57.      The concepts of airport capacity and passenger flow are closely linked. A restriction on the maximum number (flow) of passengers that can be accommodated by a coordinated airport simultaneously affects the operational capacity of that airport, considered not in the abstract but in actual terms.
58.      Whatever the extent to which the facilities at Dublin Airport are able physically to accommodate more than 32 million passengers (the theoretical or abstract capacity), if there are well-founded reasons that justify imposing a limit on that number of passengers, (29) the actual, effective capacity of those facilities will have been reduced as the requirement of an official decision binding on the body managing that airport.
59.      In short, precisely because of the limitation imposed on the number of passengers (which, logically, has an impact on the number of flights), (30) the authority approving the coordination parameters must take that operational constraint into account, inasmuch as it ‘affect[s] the performance of the airport infrastructure’. It is, as I have already indicated, a factor relevant to the ‘objective analysis of the possibilities of accommodating the air traffic’.
C.      Second question referred for a preliminary ruling
60.      In the event that the Court decides that the 32 mppa condition is a ‘relevant constraint’, the referring court wishes to ascertain whether it is permissible to cease allocating to air carriers a number of series of historical
slots to which those air carriers would otherwise be entitled under Article 8(2) of Regulation No 95/93.
61.      The question concerns, in essence, the legal nature of the historical slots and ‘whether the IAA, as competent authority, can set coordination parameters which result in the non-allocation of such slots (or certain components thereof). In that regard, there is an argument that the historical slots are in the nature of property rights and it is argued that the IAA cannot make a determination that such slots can be reduced’. (31)
62.      The provisions of EU law of which the referring court requires an interpretation in order to
resolve its doubts are, in the present question, Article 6(1) of Regulation No 95/93 and Articles 16 and 17 of the Charter.
1.      Arguments of the parties and interveners in the preliminary ruling proceedings
63.      The air carriers proceed on the premiss that the system for the allocation of slots regulated in Article 8(2) of Regulation No 95/93 confers on airlines that have used those slots regularly a property right entitling them to retain them in successive equivalent seasons.
64.      The IAA and the Dublin Airport managing body claim that that provision does not confer a property right. They take the view, in summary, that it is merely a matter of priority treatment in the grant of permission to use the airport facilities, permission which is inherent in the allocation of each slot and conditional on the existence of capacity at the airport.
65.      Ireland,
the Netherlands Government and the Commission (32) also argue in favour of an affirmative answer to the second question referred for a preliminary ruling.
2.      Assessment
66.      Article 8(2) of Regulation No 95/93 provides for ‘historical’ slots. By virtue thereof, an air carrier may continue to use in a subsequent season the slot allocated to it in a previous season if it has used that slot correctly.
67.      Historical slots provide stability and facilitate planning. For the airlines, they represent an incentive to use airport facilities efficiently, enabling them to retain their regular routes. For airports and passengers, their benefit lies in the predictability of air traffic.
68.      When allocating slots, the starting point for the airport coordinator is the pool provided for in Article 10 of Regulation No 95/93. The slot pool is a means of ensuring access to coordinated airports for new operators or airlines that wish to expand their presence.
69.      The slot pool is made up of: (a) slots underused during a season; (33) (b) new slots arising from increases in airport capacity; and (c) slots returned by airlines.
70.      The slot pool is managed by the airport coordinator. When the allocation processes for a new season commence, some slots are distributed to the historical operators and others (the slot pool) are allocated in priority to ‘new entrants’.
71.      Regulation No 95/93 provides for the allocation of slots to new entrants in order to prevent congested airports from being blocked by ‘historical’ airlines. In that way, it ensures that there are competition and opportunities for new operators or new routes. (34)
72.      In accordance with the general rule laid down in Article 8(1) of Regulation No 95/93, ‘series of slots are allocated … to applicant carriers as permissions to use the airport infrastructure for the purpose of landing or take-off for the scheduling period for which they are requested …’ (my emphasis).
73.      Article 8(2) establishes the exception for historical operators as reproduced above. (35) Pursuant to that provision, Article 8(1) is not to apply when those operators fulfil certain conditions as to the proper use of the series of slots allocated to them.
74.      The purpose of the system so designed, as Regulation (EC) No 793/2004 (36) highlighted, is to ensure the stability of operations. (37)
75.      Accordingly, Article 6(1) of Regulation No 95/93 (the first of the provisions of which interpretation is requested in this question) does not offer any pointers as to the legal nature of slots. Those pointers are to be found in other provisions of that regulation, to which I shall now refer.
76.      The understanding of historical slots as property rights that benefit from the protection of Article 17 of the Charter poses, in my view, serious difficulties.
77.      In the first place, Article 2(a) of Regulation No 95/93 defines slots as ‘permissions’. Article 8(1) of that regulation confirms that that is what they are when it refers to them as ‘permissions to use the airport infrastructure’. That is borne out by recital 8 of Regulation No 793/2004. (38)
78.      The grant of permission to use an asset confers not ownership of that asset but only the right to use it. When the ninth recital of Regulation No 95/93 states that ‘the existing system makes provision for grandfather rights’, it does not use that term
in such a way as to recognise property rights over slots, even though the latter may have an economic value.
79.      Permissions to access the facilities of an airport in certain slots are, as I have stated before, mere rights of use granted by the competent authority, in connection with certain airport infrastructure and subject to subsequent decisions of that authority. They serve to authorise a ‘permitted use’ by the holder of the interest (or by such person as the latter may designate).
80.      In the second place, the mechanism provided for in Article 8(1) of Regulation No 95/93 focuses on a scheduling period. On the expiry of that period, slots ‘… have to be returned to the slot pool as set up according to the provisions of Article 10’. The fact of being temporary is not consistent with the permanence inherent in the concept of ownership.
81.      In the third place, the use of slots is necessarily conditional. Where there is insufficient capacity to accommodate all slots, the coordination parameters are triggered and the airport coordinator may not be able to satisfy all requests for historical slots. Regulation No 95/93 provides for that contingency in Article 8(3) ‘where all requests cannot be accommodated to the satisfaction of the air carriers concerned’.
82.      Article 8(2) of Regulation No 95/93 conceives of historical slots as being ‘without prejudice to Articles 7, 8a and 9, Article 10(1) and Article 14’, (39) indicating that there are limitations inherent in their definition itself.
83.      In the fourth place, the rules governing disposal of the ‘right’ to historical slots shows that, in actual fact, air carriers cannot themselves transfer that right. Once again, a feature normally inherent in a property right (that they are freely transferable) is not present in this instance.
84.      It is true that Article 8a(1) of Regulation No 95/93 allows slots to be transferred and exchanged under the conditions which it lays down. (40) However, the extent of those conditions is such that, in accordance with Article 8a(2), transfers and exchanges ‘shall not take effect prior to the express confirmation by the coordinator’. What is more, the coordinator is granted extensive powers to refuse that confirmation. (41)
85.      In the fifth and final place, if a slot were a property right forming a permanent part of the assets of its holder (that is to say a substantive capitalised right), its elimination would, logically, entail financial compensation:
the sacrifice of that right would give rise to an obligation to compensate for its loss.
86.      However, in the light of Article 8b of Regulation No 95/93 (‘Exclusion of compensation claims’), ‘the entitlement to series of slots referred to in Article 8(2) shall not give rise to any claims for compensation in respect of any limitation, restriction or elimination thereof imposed under Community law’.
87.      Although Article 8b of Regulation No 95/93 refers to the limitations, restrictions or eliminations imposed by provisions of EU law, what is decisive (for the purposes of determining the legal nature of permissions to use slots) is that it points up their precarious, non-consolidated nature.
88.      The right to use historical slots cannot, in the final analysis, disregard the airport’s capacity as defined in the coordination parameters.
89.      I therefore take the view that Article 17 of the Charter does not preclude restrictions from being imposed on the historical slots that had been available to certain air carriers, as a result of the limitation of the maximum permissible number of passengers at a given airport. (42)
90.      By the same token, the freedom to conduct a business guaranteed in Article 16 of the Charter is likewise not compromised.
91.      The freedom to conduct a business (which, moreover, may be limited in accordance with Article 52(1) of the Charter itself) is not infringed where, in prescribing the legal regime governing the use of public infrastructure such as airports, the competent authorities adopt objective criteria, applicable equally to all operators, on the basis of which they determine the framework for activity under that regime. The measures at issue do not affect the freedom of air carriers to shape their own decisions or to adopt their business policy within that framework.
D.      Third question referred for a preliminary ruling
92.      The referring court poses this question on a conditional basis (‘if this arises for consideration strictly as a result of the Court’s answers to questions 1 and 2’).
93.      In my view, the Court’s answers to the first two questions do not have the effect that the matter to which the third question relates ‘arises for consideration’. There would, in that case, be no need to analyse the third question.
94.      By its third question, the referring court wishes to ascertain whether Regulation No 95/93 precludes airport managing bodies from taking ‘unilateral action to close the airport for a period of time, for the purpose of preventing the operation of slots … so as to avoid a breach of an annual limit of passengers …’. (43)
95.      The question thus formulated addresses a hypothetical airport closure which bears no relation to the circumstances of the dispute. There is nothing to indicate that the Dublin Airport managing body ordered or planned to order the closure of that airport ‘so as to avoid a breach of an annual limit of passengers’ in order to satisfy the 32 mppa condition.
96.      The doubt raised by the referring court ‘anticipates’ the possibility of that unlikely hypothesis materialising in the future. Consequently, as a number of the applicant carriers have argued, the question referred for a preliminary ruling is not necessary to the resolution of the dispute by the referring court and is, to that extent, inadmissible. (44)
97.      In the event that the Court decides to address the substance of the question, it is my view that, according to the provisions of Regulation No 95/93, it is difficult to imagine that the airport managing body could close the airport as a means of complying with the 32 mppa condition.
98.      Indeed:
–        In accordance with Article 6 of Regulation No 95/93, the coordination parameters approved by the IAA set the maximum number of flights for which the airport’s capacity allows during the coordination period.
–        Pursuant to Article 4(5) of that regulation, the airport coordinator allocates slots to airlines throughout that period.
–        According to Article 2(j), the airport managing body has the task of ‘administering and managing the airport facilities’.
99.      Regulation No 95/93 thus establishes a precise chain of competence:
the airport coordinator allocates slots for the entire coordination period, in accordance with parameters which, in situations such as the present case, already take into account the condition relating to the annual passenger limit.
100. The system introduced by Regulation No 95/93 is based on medium-term forecasting and contains mechanisms which avoid decisions as drastic as the closure of an airport in order to comply with a requirement known well in advance, such as the 32 mppa condition.
101. At the hearing, the airport managing body stated that the consequences of closing Dublin Airport, even temporarily, would be extremely detrimental to the island’s
inhabitants and suggested that a more rational and proportionate step to take in the event of a miscalculation would be to adopt local guidelines under Article 8(5) of Regulation No 95/93. That
measure would allow an orderly response to an unforeseen increase in the use of the airport’s facilities.
102. An airport closure may be ordered for other reasons (relating to safety, weather conditions and similar
factors), (45) but Regulation No 95/93 contains no provision envisaging a closure in order to comply with the maximum permitted number of passengers.
V.      Conclusion
103. In the light of the foregoing, I propose that the first two questions referred for a preliminary ruling by the High Court (Ireland) be answered as follows:
Article 6(1) of Council Regulation (EEC) No 95/93 of 18 January 1993 on common rules for the allocation of slots at Community airports, as amended by Regulation (EU) 2022/2038 of the European Parliament and of the Council of 19 October 2022 as regards temporary relief from the slot utilisation rules at Union airports due to an epidemiological situation or military aggression,
must be interpreted as meaning that:
(1)      In determining the coordination parameters for the allocation of slots at a coordinated airport, the competent body may take into account the conditions, included in the development consent granted by the planning authority,
that limit the total accommodation capacity to a maximum number of passengers per annum.
Those conditions may be classified as ‘relevant constraints’ and form part of the objective analysis of the possibilities of accommodating the air traffic at a particular airport.
(2)      Article 6(1) of Regulation No 95/93 and Articles 16 and 17 of the Charter of Fundamental Rights of the European Union do not preclude the determination of the coordination parameters at an airport, due to the obligation to comply with the maximum number of passengers permissible according to the national authorities, from leading to the elimination or reduction of historical slots.
104. With regard to the third question referred for a preliminary ruling, I suggest that the Court declare it inadmissible. In the alternative, I propose that it be answered as follows:
Articles 1(j), 4(5), 6(1) and 8(5) of Regulation No 95/93
must be interpreted as
not providing for the possibility that the managing bodies of an airport may take the unilateral step of closing the airport’s facilities as a means of avoiding a breach of the annual passenger limit imposed in a development consent granted by the planning authority for extension of the airport terminals.
1      Original language: Spanish.
2      ‘An Bord Pleanála’.
3      The statutory body that is the civil aviation regulator in Ireland under the Aviation Regulation Act 2001 and the Air Navigation and Transport Act 2022.
4      Council Regulation of 18 January 1993 on common rules for the allocation of slots at Community airports (OJ 1993 L 14, p. 1), as amended by Regulation (EU) 2022/2038 of the European Parliament and of the Council of 19 October 2022 as regards temporary relief from the slot utilisation rules at Union airports due to an epidemiological situation or military aggression (OJ 2022 L 275, p. 14).
5      Article 2(g) of Regulation No 95/93. According to the classification in the Worldwide Airport Slot Guidelines
adopted by the International Air Transport Association (IATA) (‘the IATA Guidelines’), such airports are defined as
‘Level 3’ (https://www.iata.org/contentassets/4ede2aabfcc14a55919e468054d714fe/wasg-edition-4-english-version.pdf (Part
1, point 5.1)).
6      Council Directive of 27 June 1985 on the assessment of the effects of certain public and private projects on the environment (OJ 1985 L 175, p. 40).
7      [Original English-language title given in Spanish-language version].
8      daa plc, formerly Dublin Airport Authority plc, is a State-owned company which manages Dublin Airport. I shall refer to it hereafter as ‘daa’ or ‘the Dublin Airport managing body’.
9      ‘The winter 2024 decision’.
10      In accordance with Section 11 of the IATA Guidelines, the summer season begins on the last Sunday in March and the winter season on the last Sunday in October.
11      ‘The summer 2025 decision’. Point 4.90 of that decision states that ‘the 2006 [local area plan], on which the 32 mppa conditions were actually based, has since lapsed, and been replaced by a new [local area plan] which provides, instead, for 40 mppa on the eastern campus’. At the hearing, a figure of 36 million passengers per annum was discussed. Although the High Court (Ireland) does not quote that figure in the order for reference, it is higher than that provided for in the 2006 Plan (paragraphs 53 and 93 of the order for reference).
12      Airport Coordination Ltd
is the independent coordinator for Dublin Airport, designated for the purposes of Article 4 of Regulation No 95/93. It is responsible for deciding how available capacity is to be allocated among the air carriers requesting slots at Dublin Airport.
13      There are six appeals: (i) daa plc v IAA, Airport Coordination Ltd, Aer Lingus Ltd, Ryanair Designated Activity Company, Emerald Airlines Ireland Ltd and Air Transport Association of America Inc. (trading as Airlines for America), Delta Air Lines Inc., JetBlue Airways Corporation and United Airlines Inc. (Record No 2024/920 JR); (ii) Aer Lingus Ltd v IAA, daa plc Airport Coordination Ltd and Air Transport Association of America Inc., Delta Air Lines Inc., JetBlue Airways Corporation and United Airlines Inc. (Record No 2024/927JR); (iii) Ryanair Designated Activity Company v IAA, daa plc, Airport Coordination Ltd and Air Transport Association of America Inc., Delta Air Lines Inc., JetBlue Airways Corporation and United Airlines Inc. (Record No 2024/928JR); (iv) Aer Lingus Ltd v IAA, daa plc and Airport Coordination Ltd (Record No 2024/1296JR); (v) Air Transport Association of America Inc., Delta Air Lines Inc., JetBlue Airways Corporation and United Airlines Inc. v IAA and daa plc, Airport Coordination Ltd, Ryanair Designated Activity Company, Aer Lingus Ltd and Emerald Airlines Ireland Ltd (Record No 2024/1297JR); and (vi) Ryanair Designated Activity Company v IAA, daa plc
and Airport Coordination Ltd (Record No 2024/1299JR).
14      The justification for the request for a preliminary ruling is contained in the explanatory ruling drawn up by the judge of the High Court Mr Barry O’Donnell on 11 December
2024 (‘the ruling of Mr Justice Barry O’Donnell of 11 December 2024’). In that ruling, he states that the wording of the request was the result of a consensus between the parties acting under the supervision of the High Court. Paragraphs 3, 4 and 5 of that ruling set out the reasons on which the reference is based.
15      This was the ruling of Mr Justice Barry O’Donnell of 11 December
2024. That decision, to which the parties and the interveners referred at the hearing, dispelled the doubts as to the admissibility of the reference originally registered at the Court of Justice, which had arisen as a result of the failure to state the reasons why the referring court (rather than only the parties to the dispute) had made the request for a preliminary ruling.
16      https://www.iata.org/contentassets/4ede2aabfcc14a55919e468054d714fe/wasg-edition-4-english-version.pdf.,
Part
1, points 3,
4 and 5.
17      According to the IATA Guidelines (Part
1, point 3.2.1), airlines are free to schedule their operations provided that they comply with the duty to communicate their schedule of operations.
18      At the hearing, Ireland stated that legal steps are underway to amend that limit.
19      Ruling of Mr Justice Barry O’Donnell of 11 December
2024, paragraph 3.
20      daa lodged an appeal against the winter 2024 decision on the basis that it did not properly reflect the actual operational capacity at the airport. In its view, that decision was contrary to Article 6 of Regulation No 95/93, inasmuch as the application of the coordination parameters assumed that, if all the slots allocated were used, the number of passengers in Terminals 1 and 2 would exceed the maximum capacity permitted in accordance with the conditions at issue by around 1.2 million. In the event, the excess recorded in the 2024 financial year was approximately 1 151 102
passengers (paragraph 6 of daa’s written observations).
21      Article 2(m) refers to ‘all technical, operational and environmental factors that affect the performance of the airport infrastructure and its different subsystems’. My emphasis.
22      Paragraph 15 of the written observations of the Netherlands Government.
23      At the hearing, the Commission expressed a similar view. After noting that the objective of Regulation No 95/93 is to manage scarce resources (slots) and optimise their use,
it defined an airport’s capacity as the volume of demand which that airport can process or manage while at the same time maintaining an adequate level of service for all parties (consumers, airlines, other operators and service providers).
24      Paragraph 16 of its written observations.
25      Paragraph 34 of the order for reference, which refers to the Planning and Development Act, 2000 and recalls that, if necessary, a court order can require compliance with the 32 mppa condition.
26      Paragraph 22 of the written observations of the Dublin Airport managing body.
27      In some of the written observations and at the hearing, there was discussion (involving conflicting opinions) of whether the decisions adopted by the planning authority in 2007 and 2008 were environmental decisions. I do not consider it necessary to comment on that discussion, given my view that the condition relating to the maximum number of passengers is an operational constraint.
28      Paragraphs 30 and 31 of the IAA’s written observations.
29      This reference for a preliminary ruling is not concerned with the legality, as such, of the decisions taken by An Bord Pleanála in 2007 and 2008 to authorise the extension of the terminals at Dublin Airport.
30      There was discussion at the hearing of how limiting the number of passengers would affect the number of flights (and allocated slots), given the variable capacity of the aircraft used. That is, in fact, a technical issue to be resolved by the competent authorities.
31      Ruling of Mr Justice Barry O’Donnell of 11 December 2024, paragraph 4.
32      The Commission suggests that this question may be hypothetical, since the historical slots were unaffected. Its objection is unfounded given that, according to the order for reference (paragraph 48), the historical slots had to be reduced as a result of the summer 2025 decision. Even though that decision was ultimately not actually implemented, on account of its provisional suspension, the legal debate as to its validity is genuine and not purely hypothetical.
33      This is the ‘use it or lose it’ rule connected with the right to historical slots.
If an airline uses at least 80% of the slots allocated to it in a season, it retains them as historical slots for the following equivalent season. If it does not reach an 80% utilisation rate, it loses those slots, which are returned to the pool to be reallocated to other air carriers.
34      For the Commission, ‘the system of historical preference means that it is very difficult for new entrants to challenge the dominant position of the traditional incumbent airlines at the most congested airports. At these airports, the mobility (turnover) of slots is very low’ (Commission staff working paper, Impact Assessment, accompanying the document Proposal for a Regulation of the European Parliament and of the Council on common rules for the allocation of slots at European Union airports (Recast) ((SEC(2011) 1443 final), paragraph 46).
35      Point 9 of this Opinion.
36      Regulation of the European Parliament and of the Council of 21 April
2004 amending Regulation No 95/93 (OJ 2004 L 138, p. 50).
37      Recital 9 of Regulation No 793/2004: ‘In order to encourage regular operations at coordinated airports it is necessary to provide that grandfather rights relate to series of slots. At the same time, Member States should, when defining capacity parameters, be able to take account of operational and environmental constraints’. When adopting the coordination parameters provided for in Article 6 of Regulation No 95/93, the competent authority must necessarily take into account, along with the relevant constraints, the existing historical slots.
38      ‘…
slot allocation should be considered as giving air carriers permission to access the airport facilities for landing and taking-off at specific dates and times for the duration of the period for which the permission is granted’. At the hearing, the Commission noted that the choice of the term ‘permission’ in the definition of
‘slot’ was deliberate: during the legislative process, the term ‘entitlements’ was replaced by the term ‘permission’. See paragraphs 11 and 12 of the Proposal for a Regulation of the European Parliament and of the Council amending Regulation No 95/93, COM/2001/0335 final – COD
2001/0140 (OJ 2001 C 270 E, p. 131).
39      My emphasis. In my view, it is immaterial for the purposes of the present case that that list does not include Article 6 of Regulation No 95/93.
40      Some air carriers seek to rely on Section
5, concerning ‘Exchange of slots’, of the Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions on the application of Regulation No 95/93 …, of 30 April 2008, (COM(2008) 227 final), to highlight the possibility of transferring slots for monetary and other consideration. In actual fact, the Commission simply states that ‘the text of the current regulation is silent on the question of exchanges with monetary and other consideration to reflect differences in value between slots at different times of day and other factors’.
41      Article 8a(3) of Regulation No 95/93 imposes restrictions on the transfer and exchange of slots allocated to a new entrant so as to ‘restrict the privileges corresponding to air carriers covered by that definition to genuine new entrants’
(recital 7 of Regulation (EU) 2021/250 of the European Parliament and of the Council of 16 February 2021
amending Council Regulation (EEC) No 95/93 as regards temporary relief from the slot utilisation rules at Union airports due to the COVID-19 crisis (OJ 2021 L 58, p. 1)).
42      It goes without saying that those restrictions must comply with the criteria of proportionality and non-discrimination between the air carriers affected. The second question referred for a preliminary ruling does not extend to the application of those criteria to the present case but does cover the (prior and more general) issue of whether it is permissible to cease allocating to air carriers a number of series of historical slots which they had been enjoying.
43      The ruling of Mr Justice Barry O’Donnell of 11 December 2024 contains similar wording: ‘a question arises as to whether [Regulation No 95/93] prohibits an airport management body from taking unilateral action to close the airport for a period of time, for the purpose of preventing the operation of allocated slots so as to avoid a breach of the annual passenger limitation’ (paragraph 5).
44      It is settled case-law that the function of the Court of Justice in the preliminary ruling procedure is to contribute to the effective administration of justice in the Member States, rather than to give advisory opinions on general or hypothetical questions. Judgment of 4 September
2025, Kwizda Pharma II,
C‑451/24, EU:C:2025:663, paragraph 46 and the case-law cited.
45      As the Commission correctly states (paragraph 65 of its written observations), an airport closure should in any event comply with other provisions of EU law, such as Regulation (EC) No 1008/2008 of the European Parliament and of the Council of 24 September 2008 on common rules for the operation of air services in the Community (OJ 2008 L 293, p. 3).