C-27/00

OPINION OF MR ALBER — JOINED CASES C-27/00 AND C-122/00

O P I N I O N OF ADVOCATE GENERAL ALBER delivered on 20 September 2001 1

I — Introduction I I— Legal background

A — Council Regulation (EC) No 925/1999 of 29 April 1999 on the registration and operation within the Com- munity of certain types of civil subsonic jet aeroplanes which have been modified and recertificated as meeting the standards of volume I, Part II, Chapter 3 of Annex to 1. These two reference for preliminary the Convention on International Civil Avi- rulings concern the validity of a provision ation, third edition (July 1993) ('the Regu- of Regulation (EC) No 925/1999. That lation') 4 regulation restricts the use of aeroplanes at European airports, in the interests of protection against noise. The Court is asked whether it is lawful for the regulation to exclude aeroplanes which have been completely re-engined from those restric- tions only if the engines have what is known as a by-pass ratio of three or more, while a lower by-pass ratio leads to the application of restrictions on use. 2Omega intends to equip Boeing 707s with new 2. The aim of the Regulation is to reduce engines which have a by-pass ratio of aircraft noise at airports in the Community 1.74. 3Omega claims that as a result of by laying down rules for the operation and further technical measures these aeroplanes registration of older aeroplanes which have are not in fact noisier, and are moreover been modified to reduce their noise. On its more economical and cleaner. background in international and Commu- nity law, the report of José Valverde López,

Chapter 1 covers aeroplanes that were among the noisiest at the time and may now no longer be used. 3. The issue in the present proceedings is not, however, modification by means of 'hushkits', but complete re-engining. The Regulation prohibits the use of modified aeroplanes at airports in the Community, unless they have been modified by complete re-engining with engines having a by-pass ratio of three or more. Aeroplanes with Chapter 2 aeroplanes are, under Directive new engines with a by-pass ratio of less 92/14/EEC, [ 6 ] to be phased out from April than three may thus in principle not be used 1995 to April 2002. From 1 April 2002 in the Community. Only aeroplanes which they may no longer be used in the EU, even were already operated in the Community if exempted in the annex to the directive on the date of application of the Regulation referred to above. These Chapter 2 aero- could continue to be used. planes may, however, be equipped with "hushkits" so that they produce less noise and can be included in Category 3.

5 — Report on the proposal for a Council Directive on the registration and use within the Community of certain types or civil subsonic jet aeroplanes which have been modified and recertificated as meeting the standards of Volume I, Part II, Chapter 3 of Annex 16 to the Convention on Inter- national Civil Aviation, third edition (July 1993), 21 July 1998, Parliament document No. A4-0279/98. 6 — Council Directive of 2 March 1992 on the limitation of the operation of aeroplanes covered by Part II, Chapter 2, Volume 1 of Annex 16 to the Convention on International 4. To understand the importance of Civil Aviation, second edition (1988), OJ 1992 L 76, p. 21. by-pass ratio, a brief description of

8. The prohibition of re-engined aeroplanes whose engines have a by-pass ratio of less than three follows from Article 3 in con- junction with the definition in Article 2(1) and (2) of the Regulation. 6. In a turbofan engine the noise from the exhaust is reduced because, in addition to the high-speed airflow through the core of the engine (the actual turbine) an airflow at lesser speed is directed through a duct surrounding the engine core (the by-pass 9. Article 3, headed 'Non-complying aero- airflow). This by-pass airflow is produced planes', reads as follows: by a fan at the front of the engine. The fan contributes to the overall thrust of the engine. The by-pass airflow has the result that when the core airflow leaves the engine it meets the external air less turbulently. As a result, the noise of the exhaust is less than ' 1 . Recertificated civil subsonic jet aero- where there is no by-pass airflow. The planes shall not be registered in the higher the ratio of the by-pass airflow to national register of a Member State as the core airflow, the less noise is pro- from the date of application of this Regu- duced. 7 The by-pass ratio of three used as lation. the limit in the Regulation means that the

8 — The expert for the United Kingdom Department of the Environment submitted in the main proceedings, however, 7 — According to http://www.jetfire.de/engines.htm, visited on that take-off noise has hitherto been much more important 27 June 2001, 'the cold by-pass flow surrounds the hot, fast because it affects a much greater proportion of the popu- and noisy exhaust of the core like a silencer'. lation.

'a civil subsonic jet aeroplane initially certificated to Chapter 2 or equivalent 4. Recertificated civil subsonic jet aero- standards, or initially not noise-certificated planes which are on the registers of which has been modified to meet Chapter 3 Member States may not be operated at standards either directly through technical airports in the territory of the Community measures or indirectly through operational as from 1 April 2002 unless they have been restrictions; civil subsonic jet aeroplanes operated in that territory before the date of which initially could only be dual-certifi- application of this Regulation.' cated to the standards of Chapter 3 by means of weight restrictions, have to be considered as recertificated aeroplanes; civil subsonic jet aeroplanes which have been modified to meet Chapter 3 standards by being completely re-engined with engines having a by-pass ratio of three or 10. Article 2(1) of the Regulation first more are not to be considered as recertifi- defines a 'civil subsonic jet aeroplane' cated aeroplanes' (emphasis added).

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12. The 'chapters' referred to are, accord- of aeroplanes to Member States' reg- ing to Article 2(3) of the Regulation, 'the isters as from the date of application of noise standards as defined in Volume I, Part this Regulation can be considered as a II, Chapter 2 and Chapter 3 respectively of protective measure aimed at preventing Annex 16 to the Convention on Inter- a deterioration of the noise situation national Civil Aviation, third edition (July around Community airports as well as 1993)'. improving the situation regarding fuel burn and gaseous emissions'.

16. Article 2 of the Agreement on Tech- nical Barriers to Trade 10 states:

2.8 Wherever appropriate, Members shall specify technical regulations based on '2.2 Members shall ensure that technical product requirements in terms of perform- regulations are not prepared, adopted or ance rather than design or descriptive applied with a view to or with the effect of characteristics.' creating unnecessary obstacles to inter- national trade....

I I I— Facts 2.3 Technical regulations shall not be maintained... if the... objectives can be addressed in a less trade-restrictive manner. 17. The main proceedings are brought by Omega Air Ltd and several associated undertakings. They will be referred to below as Omega.

2.4 Where technical regulations are required and relevant international stan- dards exist... Members shall use them, or 18. According to the order for reference in the relevant parts of them, as a basis for Case C-27/00, Omega is concerned with their technical regulations except when trading in aircraft, primarily Boeing 707s. such international standards or relevant It also carries on related activities, such as parts would be an ineffective or inappropri- aircraft engine maintenance. Omega is ate means for the fulfilment of the legit- developing a programme for the gradual imate objectives pursued, for instance replacement of the engines in Boeing 707s because of fundamental climatic or geo- by newly manufactured engines with a by-pass ratio of 1.74. The modified aero- planes will be referred to below as Omega 10 — Annex I to the WTO Agreement, OJ 1994 L 336, p. 86. 707s.

11 — Omega acknowledges that in the other two programmes engines with a by-pass ratio over three were used. It refers to another programme which is also based on the engines intended for use in the present case, but envisages replacement of only some of the engines. However, 22. Before reaching a decision, Omega Aviation Upgrade Technologies Inc., in connection with its 'Registration of Securities of a Small-Business Issuer' looked at the use of other engines with a (Form 10-SB) of 12 July 1999 for the US Securities and higher by-pass ratio. Since the use of such Exchange Commission, stated its intention of replacing Pratt & Whitney JT8D engines in Boeing 727s by Rolls engines would have necessitated extensive Royce RB211-535E4 engines with a by-pass ratio of 4.3.

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of the question referred to the Court of (iii) such rights as private parties may Justice. The High Court rejected as unar- derive from the General Agreement guable the other three grounds advanced by on Tariffs and Trade and/or the Agree- Omega, relating respectively to discrimi- ment on Technical Barriers to Trade?' nation, legitimate expectations and breach of the Chicago Convention on Inter- national Civil Aviation, 7 December 1944.'

26. The High Court of Ireland states that the case before it raises the question of the 25. It therefore refers the following ques- validity of the Regulation. As it does not tion to the Court for a preliminary ruling: have jurisdiction to decide the point, it refers the following question to the Court:

29. Omega regards the insertion of the provision at issue into the draft regulation IV. the compatibility of that provision with in November 1998 as incomprehensible. It the Agreement establishing the World submits in detail that the statement of Trade Organisation and in particular reasons makes no reference to the following the Agreement on Technical Barriers to aspects: Trade annexed thereto?'

— why the Regulation covers re-engining 27. With the order for reference, the High at all; Court, Dublin, referred to the already pending Case C-27/00 and requested the Court to hear both cases together expedi- tiously.

— why it bases the limit on by-pass ratio;

V — Legal assessment

— why the limit is a by-pass ratio of three;

A — The duty to give reasons

30. Omega states that it learnt in early 33. The United Kingdom Government con- September 1998 of the proposal to intro- siders, finally, that it is not permissible duce a by-pass ratio criterion, and at once when assessing the statement of reasons in started to make its interests known to the the Regulation to take account of alleged Commission, Members of the European contradictions in the reasons of the Com- Parliament and representatives of the mon Position of the Council for the intro- Member States. duction of the provision at issue. Nor is the Council obliged to state reasons for amend- ing the Commission's proposal for a legal measure. Moreover, the Common Position did not express a view on the importance of by-pass ratio for reducing noise. 31. The other parties observe, referring to the case-law, that the statement of the reasons for a general measure may be confined to indicating the general situation which led to its adoption and the general objectives which it is intended to achieve. It Opinion is not necessary, on the other hand, to give reasons for every technical choice in the regulation. They take the view that the statement of reasons in the Regulation discloses its objectives and the starting situation sufficiently clearly, whereas the decision to set a by-pass ratio of three is a 34. The requirements which statements of technical means for achieving those objec- reasons for measures of general application tives. The reasons for that need not be must comply with are limited, according to

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12 — Case C-84/94 United Kingdom v Council [1996] ECR 40. Recital 5 at the same time states with- I-5755, paragraph 74. 13 — Case C-122/94 Commission v Council [1996] ECR I-881, out reservation, finally, that re-engined paragraph 29. aeroplanes may achieve the same results 14 — See, for example, Case C-150/94 United Kingdom v as modern aeroplanes. By-pass ratio is not Council [19981 ECR I-7235, paragraph 25, and Case 5/67 Beus (1968) ECR 83, at p. 95. mentioned. I - 2582

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41. Only the definitions of civil subsonic jet 43. More extensive obligations to state aeroplanes and recertificated civil subsonic reasons could arise if it is taken into jet aeroplanes in Article 2(1) and (2) of the account that the legislature — as will be Regulation use the by-pass ratio of three to discussed in detail — had a broad discre- delimit the types of aeroplane covered by tion in the present case. In this respect, the the Regulation. No express reason is given Court has held in connection with Com- for the use of that criterion. mission decisions on agriculture:

'... Where the Commission has such lati- tude [a wide power for the assessment of complex economic situations], it has a duty not only to identify the factors which influenced its decision but also to state their effect.' 15

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45. As regards the alleged departure from 48. Omega takes the position, however, international standards and from the WTO that the Court must examine strictly Agreement on Technical Barriers to Trade, whether the principle of proportionality the duty in Community law to state reasons has been complied with, because the con- cannot extend to showing that every provi- tested provision diverges from the Chicago sion is consistent with such international Convention, the normal legislative rules or giving reasons for any divergence. approach of Community law, and the law The latter would even contain an implied of the WTO, and seriously affects Omega's admission of a breach of international law. business activity without producing a cor- responding benefit for the Community. Omega also points out that the legislature did not have to make an urgent decision in this case and was able to rely on definite scientific knowledge when assessing the situation. 46. The lawfulness of the use of the by-pass ratio of three as a limiting criterion is not therefore called into question by the Regu- lation's statement of reasons.

49. Omega disputes both the appropriate- ness and the necessity of the contested provision for achieving the objective. Defining a by-pass ratio takes no account at all of actual noise performance. Omega B — Proportionality accepts that by-pass ratio is of importance for the noise profile of an engine, but asserts that the aeroplanes to be re-engined by it would, because of special technical measures, be comparable in all respects with modern aeroplanes under Chapter 3 Submissions of the parties whose engines have a considerably higher by-pass ratio.

laterally but slightly quieter on approach. It 54. They point out that because of the wide even appears that the comparison aero- legislative discretion judicial review is planes may be noisier on approach than the limited to cases of manifest error of assess- Omega 707 on sideline measurement. ment, misuse of powers or exceeding the bounds of discretion. In the main proceed- ings the United Kingdom Department of the Environment referred to the case-law of the Court of Justice in matters of agricul- ture, according to which a regulation may be declared to be disproportionate only if it is manifestly inappropriate for achieving 51. Omega then observes that the emission the objective pursued. figures of the engines envisaged, in terms of hydrocarbons, carbon monoxide and oxides of nitrogen, are below the figures for engines of a comparable Airbus A300-B4-200F, and in terms of hydrocar- bons and oxides of nitrogen even below the figures for all comparable aeroplanes. For fuel burn too, a Boeing 707 re-engined by Omega is over 40% better than an Airbus 55. The other parties further stress that the A300-B4-200F. Regulation is intended not only to reduce noise but also to limit other harm to the environment. They are of the opinion that the by-pass ratio of an engine is inextri- cably linked with noise generation, and also with fuel burn and gaseous emissions.

57. The expert from the United Kingdom ence to a by-pass ratio of three is a less Department of the Environment submitted restrictive means than the definition of new in a report for the Commission that in standards for noise, gaseous emissions and addition to the subjective evaluation of fuel burn. On the one hand, the number of measurements at specific points the re-engined aeroplanes is relatively small. influence of the noise measured there on On the other hand, the expense of defining the size of the 'noise footprint' — the area new standards is very great, and it would in affected by a specified noise level — particular require the involvement of inter- should also be taken into account. The national institutions. The existing noise expert states that a reduction by 5 decibels standards apply to whole aeroplanes, while leads to a reduction of that area on take-off the standards for certain emissions apply to by over 50%, and another 5 decibels would engines. They are not appropriate for lead to a reduction by over 80%. attaining the objectives of the Regulation.

58. The United Kingdom Government and Opinion the Irish Aviation Authority state that the definition of noise limits could not serve the more comprehensive aims of the Regu- lation in the field of environmental pro- tection as well as the contested provision, which may be expected to produce (1) The criterion of review to be applied improvements in fuel burn and gaseous emissions as well.

(a) The principle of proportionality

59. The Commission and the Council refer to the high degree of complexity of measur- ing aircraft noise. The Regulation is also not meant to anticipate the agreement of new standards within the ICAO. They 61. The Court defines the principle of point out, finally, that all those concerned proportionality as follows: could be aware of the forthcoming regu- lation from 1998.

(c) No restriction of review for appropri- ateness (b) Discretion of the legislature

63. The criterion of review to be applied is, however, relativised by the Court: 65. According to the formulations used in consistent case-law in the field of agricul- ture, review might even be restricted further. In that field the Court regularly states, when reviewing proportionality, 'In a sphere in which the Community that 'the legality of a measure adopted in legislature is called on to undertake com- that sphere can be affected only if the measure is manifestly inappropriate having 16 — Case 265/87 Schräder [1989] ECR 2237, paragraph 21. 17 — See, for example, Case C-84/94, cited in note 12, 18 — Norbrook Laboratories, cited in note 17, paragraph 90. paragraph 57; Case C-233/94 Germany v Council and Commission [1997] ECR I-2405, paragraph 54; and Case 19 — Compare, with respect to transport policy, Joined Cases C-127/95 Norbrook Laboratories [1998] ECR I-1531, C-248/95 and C-249/95 SAM Schiffahrt and Stapf [1997] paragraph 89. ECR I-4475, paragraph 23 et seq.

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regard to the objective which the compet- 67. The conclusion must be that manifest ent institution intends to pursue'. 20 The errors of assessment with respect to necess- stages of necessity and proportion between ity and the proportion between the con- the contested measure and the aim pursued tested measure and its aim may also lead to would then no longer have to be exam- annulment of the contested provision. 25 ined. 21

(d) Review of manifest error of assessment

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proof of the error. If such proof is not part of the legislature, the Court may not possible, that goes to the onus on the ignore that. That is all the more so if the person who asserts that a regulation in basic facts must have already been known unlawful. 27 to the legislature during the legislative procedure.

70. If, moreover, already in the legislative procedure specific facts have been sub- (2) Application to the reference for a mitted which contradict the view taken by preliminary ruling the legislature, then it may be obliged to take those facts into account. 28

(a) Legislative objective aeroplanes. The figures submitted by Omega do not, however, impose the con- clusion that its re-engined aeroplanes would be just as quiet as aeroplanes con- structed with the aim of complying with the noise standards of Chapter 3. The measure- ments on take-off and laterally at least are 73. The legislative objective of the refer- higher than for the comparison aeroplanes ence to a by-pass ratio of three or more is mentioned. If one accepts as true Omega's the reduction of environmental harm assertion that the human ear can perceive a caused by air traffic, with respect in difference only from noise differences of 3 particular to noise, fuel burn and harmful decibels, then Omega's aeroplanes would emissions. The basis of that determination be audibly noisier measured laterally, but was the view that engines with a by-pass on take-off there would be no perceivable ratio of three or more are not as noisy, difference, and their advantage on consume less fuel and also emit less harm- approach would be at the margin of what ful substances than engines with a by-pass is audible. It would in principle be within ratio of less than three. the legislature's discretion in that situation to attach greater weight to the disadvan- tages of Omega's aeroplanes than to their advantages.

(b) Appropriateness

76. Moreover, Omega has not measured these figures in practice, but can only produce estimates. Omega has not there- 74. There is a manifest error in the assess- fore shown convincingly that the provision ment of appropriateness if it is the case that at issue was manifestly inappropriate for aeroplanes under Chapter 2 which are attaining the objective of improved pro- equipped with new engines whose by-pass tection of the environment. ratio is below three are at least comparable, as regards noise, fuel burn and emissions, with aeroplanes under Chapter 3.

used in Article 2(1) of Directive 92/14 and emissions separately, which may even, Article 4(e) of Directive 89/629/EEC 30 as depending on the legislative objective, go an alternative to compliance with noise beyond the requirements of Chapter 3. limits. This alternative to compliance with That would be at least as suitable for noise limits is already suggested in Resol- achieving the legislative objective, since in utions A31-11 and A32-8 of the ICAO would guarantee compliance with those Assembly, according to which the Member standards in any event. The criterion of States, if anticipating the application of the by-pass ratio alone, by contrast, does not limits in Chapter 3, are to provide for an guarantee any precise standards for the exception for aeroplanes having engines individual factors. That criterion allows with a high by-pass ratio. only a presumption that the aeroplanes certificated will perform better than those not certificated. At least in theory, that criterion would, however, also permit the use of aeroplanes or engines with less good performance. 78. It cannot therefore be said that the criterion of by-pass ratio is inappropriate for reducing aeroplane noise.

(c) Necessity 81. The definition of specific standards would at the same time be less burdensome, because it would not restrict the freedom of choice of designers and airlines as regards the technical solution to be used for attaining the regulatory objective. As 79. A manifest error in the assessment of Omega rightly submits, that view is con- necessity presupposes that other measures firmed in the law of public procurement can be adopted which are just as appropri- both at Community level and at WTO ate for achieving the aim pursued, but are level. A r t i c l e 1 8 ( 4 ) of D i r e c t i v e less burdensome for manufacturers in the 93/38/EEC, 31 Article 14(6) of Directive position of Omega and at least no more 92/50/EEC 32 and Article VI(2)(a) of the burdensome for third parties. Agreement on Government Procurement 33 each provide that requirements as to the technology used are permitted only in

84. As regards anticipation of stricter inter- national standards, European rules may 82. The arguments put forward in the well prejudice them politically, but cer- present case against such standards fail to tainly not as a matter of law. Nor is it convince. There is no apparent reason why apparent why international bodies should those standards should be confined to noise be involved in setting new standards, while without taking reasonable account of fuel an additional criterion not used inter- consumption or harmful emissions. The nationally may be determined unilaterally. Commission may be right in its view that ascertaining whether a type of aeroplane complies with such standards is more difficult than simply taking account of the by-pass ratio. However, it also submits that noise values at least are already ascertained 85. Further indications of the lack of in the context of certification, still necess- necessity of a rule which fastens exclusively ary, of the aeroplane type for the purpose on by-pass ratio are the earlier references to of compliance with Chapter 3. Stricter by-pass ratio in Directives 92/14 and standards could link up with that examin- 85/629 and in ICAO Resolutions A31-11 ation. Moreover, there should be no objec- and A32-8. They provide that aeroplanes tion to imposing the costs of additional may be certificated if they either comply examinations on the person seeking to have with noise limits or have a by-pass ratio of a type of aeroplane certificated. two or more or a high by-pass ratio as the case may be. Those provisions manifestly proceed from the assessment that aero- planes with lower by-pass ratios too may be able to comply with noise limits.

91. The United Kingdom Government, the Irish Aviation Authority, the Commission 89. The Court — according to Omega — and the Council refer to the judgment in distinguishes, when reviewing the compati- Case C-149/96, according to which a poss- bility of Community measures with inter- ible conflict with WTO law cannot affect national agreements, according to whether the validity of a regulation. They submit in those measures are based on 'reciprocal and the alterative that the provisions of the mutually advantageous arrangements'. Agreement on Technical Barriers to Trade are not infringed. 3 7 35 — A prohibition of re-engined aeroplanes would moreover appear open to challenge for the same reasons. 36 — Portugal v Council [1999] ECR I-8395, paragraph 47. 37 — See point 16 above.

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93. The Community's position in those 96. The conclusion in the judgment in Case negotiations would be seriously affected if C-149/96, namely that 'having regard to Community law recognised a unilateral their nature and structure, the WTO agree- direct effect of obligations under WTO ments are not in principle among the rules law. in the light of which the Court is to review the legality of measures adopted by the Community institutions', 40 must therefore be maintained. The exceptions mentioned there do not apply here. The fact that the provisions of the Agreement on Technical Barriers to Trade 41 referred to above are 94. Direct reliance on rules of WTO law as perhaps sufficiently precise and uncon- against measures taken by WTO members ditional in their wording to be amenable appears inappropriate from the point of to direct application cannot lead to a view of WTO law as well, however. different conclusion. They are subject to Regardless of their wording, all provisions the general condition of WTO law that the of WTO law are subject to a general members of the WTO are to comply with reservation which accords the States con- their obligations not by direct effect of cerned various possibilities of reacting to a breach. 39 — Compare Case C-149/96, cited in note 36, paragraph 49, with further references. 40 — Cited in note 36, paragraph 47. 38 — Cited in note 36, paragraph 36 et seq. 41 — See point 16 above.

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WTO law in their legal systems but exclus- 99. Omega also objects to the fact that ively by specific transposition of those re-engining with engines with a by-pass obligations. ratio below three is equated with modifying aeroplanes by the installation of 'hushkits'.

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102. The Irish Aviation Authority takes the parable situations must not be treated view that it is in any event justified to differently and different situations not subject re-engined aeroplanes to stricter treated alike unless such treatment is objec- requirements than older aeroplanes. Since tively justified. 42 the by-pass ratio is moreover decisive for noise performance, engines with a higher by-pass ratio may be treated differently from engines with a low by-pass ratio. Finally, American and European undertak- ings are affected equally by the Regulation. 105. Its special importance alongside the principle of proportionality lies in the fact that it prohibits the introduction of meas- ures which are proportionate in principle if they affect comparable situations differ- ently without objective justification. For 103. The Commission and the Council this element of review, it is thus irrelevant emphasise that no reasons are given for whether — as put forward here — the this question and therefore base their reference to a by-pass ratio of three is not observations on assumptions. Differentiat- necessary. What matters is whether like ing according to by-pass ratio is justified by situations have been treated differently the consequences of the by-pass ratio for without objective justification. noise, fuel burn and gaseous emissions. The distinction as against aeroplanes equipped from the outset with the same engine is justified by the fact that the latter were also certificated originally under Chapter 3. Equal treatment with re-engined aeroplanes 106. Omega adduces three different follows from the fact that in both cases the comparison groups: original construction is considerably modi- fied. Any disadvantageous treatment of American manufacturers is to be dealt with, finally, only in the context of the questions referred concerning WTO law.

— re-engined aeroplanes with engines 109. Moreover, it must be presumed that with a by-pass ratio below three and newer aeroplanes which were already aeroplanes merely modified with hush- designed with a view to the standards of kits. Chapter 3 will in principle perform better than older aeroplanes which meet the standards under Chapter 3 only as a result of being modified.

107. No sufficient indications have been submitted of direct or covert disadvan- tageous treatment of US undertakings by 110. Re-engined aeroplanes are thus not the reference to a by-pass ratio of three. comparable with aeroplanes which were The fact that no undertaking located in the originally designed in accordance with the European Community and only one requirements of Chapter 3. remaining American undertaking manufac- tures engines with a by-pass ratio below three if anything confirms the Commis- sion's view that such engines no longer correspond to the state of technology.

improvement in noise emission will pre- engining with engines with a higher by-pass sumably cause loss of performance. ratio. That would also apply to a compari- son with aeroplanes which were designed from the outset in accordance with Chapter 3. However, modification with hushkits would also lead to poorer noise results. 113. Not every difference between From the point of view of the principle of comparison groups, however, can preclude equal treatment, the common points of the treating them in the same way, since comparison groups adduced are preponder- otherwise any general rule would be ant, not the differences between them. impossible. Rather, it must be the case that the differences between the comparison groups actually require different treatment. As already stated, the legislature was entitled to assume that re-engining with engines with a by-pass ratio below three 114. There is therefore no indication of a will lead to worse noise results than re- breach of the principle of equal treatment.

VI — Conclusion

115. I therefore propose the following ruling:

Council Regulation (EC) N o 925/1999 of 29 April 1999 on the registration and operation within the Community of certain types of civil subsonic jet aeroplanes which have been modified and recertificated as meeting the standards of volume I, Part II, Chapter 3 of Annex 16 to the Convention on International Civil Aviation, third edition (July 1993) is invalid, in so far as in Articles 2 and 3 it prohibits the operation in the Community of civil subsonic jet aeroplanes which have been modified to meet Chapter 3 standards by being completely re-engined with engines having a by-pass ratio below three.