1.

In the present request for a preliminary ruling under Article 267 TFEU, the Tribunal Judicial da Comarca de Lisboa (District Court, Lisbon, Portugal) has referred three questions to the Court for a preliminary ruling concerning the interpretation of the concept of ‘extraordinary circumstances’ referred to in Article 5(3) of Regulation (EC) No 261/2004 of the European Parliament and of the Council of 11 February 2004 establishing common rules on compensation and assistance to passengers in the event of denied boarding and of cancellation or long delay of flights, and repealing Regulation (EEC) No 295/91. ( 2 )

2.

The request has been made in proceedings between LE (‘the applicant passenger’) and Transportes Aéreos Portugueses SA (‘TAP’), an air carrier, concerning TAP’s refusal to pay compensation to the applicant passenger when his flight was subject to a long delay. TAP claims that there were ‘extraordinary circumstances’, within the meaning of the abovementioned provision, connected with the disruptive behaviour of another passenger on board the aircraft intended to be used to transport passengers on the airline in question.

3.

The referring court asks inter alia whether that behaviour which, according to the pilot in command, jeopardised safety on board the flight and made it necessary to make an unscheduled stop in order to disembark the disruptive passenger, constitutes an ‘extraordinary circumstance’. The referring court also asks whether the air carrier may rely on those ‘extraordinary circumstances’ even though they arose not on the flight booked by the applicant passenger, but on the preceding flight made by the same aircraft. Lastly, the referring court asks whether, in the present case, the air carrier took all reasonable measures to avoid the delay in arrival.

4.

The Convention on Offences and Certain other Acts committed on Board Aircraft (‘the Tokyo Convention’) ( 3 ) was signed in Tokyo on 14 September 1963 and entered into force on 4 December 1969.

5.

Article 1(1)(a) and (b) of the Tokyo Convention provides:

‘1.   This Convention shall apply in respect of:

…’

6.

Article 6 of that convention provides:

‘1.   The aircraft commander may, when he has reasonable grounds to believe that a person has committed, or is about to commit, on board the aircraft, an offence or act contemplated in Article 1, paragraph 1, impose upon such person reasonable measures including restraint which are necessary:

2.   The aircraft commander may require or authorise the assistance of other crew members and may request or authorise, but not require, the assistance of passengers to restrain any person whom he is entitled to restrain. Any crew member or passenger may also take reasonable preventive measures without such authorisation when he has reasonable grounds to believe that such action is immediately necessary to protect the safety of the aircraft, or of persons or property therein.’

7.

Article 8(1) of that convention states:

‘The aircraft commander may, in so far as it is necessary for the purpose of subparagraph (a) or (b) of paragraph 1 of Article 6, disembark in the territory of any State in which the aircraft lands any person who he has reasonable grounds to believe has committed, or is about to commit, on board the aircraft an act contemplated in Article 1, paragraph 1(b).’

8.

Recitals 1, 14 and 15 of Regulation No 261/2004 state:

…

9.

Under the heading ‘Cancellation’, Article 5(1) and (3) of that regulation provides:

‘1.   In case of cancellation of a flight, the passengers concerned shall:

…

…

3.   An operating air carrier shall not be obliged to pay compensation in accordance with Article 7, if it can prove that the cancellation is caused by extraordinary circumstances which could not have been avoided even if all reasonable measures had been taken.’

10.

Under the heading ‘Right to compensation’, Article 7(1) of that regulation provides:

‘Where reference is made to this Article, passengers shall receive compensation amounting to:

In determining the distance, the basis shall be the last destination at which the denial of boarding or cancellation will delay the passenger’s arrival after the scheduled time.’

11.

Article 2(7) of Regulation (EU) No 376/2014 of the European Parliament and of the Council of 3 April 2014 on the reporting, analysis and follow-up of occurrences in civil aviation, amending Regulation (EU) No 996/2010 of the European Parliament and of the Council and repealing Directive 2003/42/EC of the European Parliament and of the Council and Commission Regulations (EC) No 1321/2007 and (EC) No 1330/2007 ( 4 ) provides:

‘For the purposes of this Regulation the following definitions apply:

…

12.

Article 4(1)(a) of that regulation provides:

‘1.   Occurrences which may represent a significant risk to aviation safety and which fall into the following categories shall be reported by the persons listed in paragraph 6 through the mandatory occurrence reporting systems pursuant to this Article:

13.

Article 1 of Commission Implementing Regulation (EU) 2015/1018 of 29 June 2015 laying down a list classifying occurrences in civil aviation to be mandatorily reported according to Regulation (EU) No 376/2014 of the European Parliament and of the Council ( 5 ) provides:

‘The detailed classification of the occurrences to be referred to when reporting, through mandatory reporting systems, occurrences pursuant to Article 4(1) of Regulation (EU) No 376/2014 is set out in Annexes I to V to this Regulation.’

14.

As regards security, point 6(2) of Annex I to Implementing Regulation (EU) 2015/1018 lists ‘difficulty in controlling intoxicated, violent or unruly passengers’ as one of the ‘occurrences pursuant to Article 4(1) of Regulation (EU) 376/2014’.

15.

Point 3(g) of Annex V to Regulation (EU) 2018/1139 of the European Parliament and of the Council of 4 July 2018 on common rules in the field of civil aviation and establishing a European Union Aviation Safety Agency, and amending Regulations (EC) No 2111/2005, (EC) No 1008/2008, (EU) No 996/2010, (EU) No 376/2014 and Directives 2014/30/EU and 2014/53/EU of the European Parliament and of the Council, and repealing Regulations (EC) No 552/2004 and (EC) No 216/2008 of the European Parliament and of the Council and Council Regulation (EEC) No 3922/91 ( 6 ) provides that ‘a pilot in command must take all necessary measures so as to minimise the consequences on the flight of disruptive passenger behaviour’.

16.

Point 7.3 of that annex states that, ‘in an emergency situation, which endangers the operation or the safety of the aircraft and/or persons on board, the pilot in command must take any action he/she considers necessary in the interest of safety. When such action involves a violation of local regulations or procedures, the pilot in command must be responsible for notifying the appropriate local authority without delay’.

17.

As is apparent from the grounds for the request for a preliminary ruling, the facts set out below gave rise to the case brought before the referring court. The applicant passenger booked a flight with TAP from Fortaleza (Brazil) to Oslo (Norway), with a connecting flight in Lisbon (Portugal) which was operated by the same airline. The first leg of the flight, from Fortaleza to Lisbon, was scheduled to depart at 23.05 on 21 August 2017 and to land at Lisbon airport at 10.15 on 22 August 2017. The second leg of the flight, from Lisbon to Oslo, was scheduled to land at the destination airport at 18.10 on 22 August 2017.

18.

Before being used for the first leg of the flight, the TAP aircraft had to make a flight from Lisbon to Fortaleza. However, during that flight, for safety reasons, the aircraft had to be diverted to Las Palmas (Spain) in order to disembark a disruptive passenger who had bitten another passenger and assaulted various other passengers and cabin crew members who had tried to calm him. Consequently, the flight to Fortaleza was subject to a delay of 4 hours and 18 minutes, thus causing a delay to the next flight, which was to be made by the same aircraft, and which finally landed in Lisbon at 13.33 on 22 August 2017.

19.

As a result of the delay to the first leg of the flight, the applicant passenger missed his connecting flight from Lisbon to Oslo. Since TAP makes only one flight per day from Lisbon to Oslo, the applicant passenger had to wait for the next flight, scheduled for the following day, as a result of which his arrival at the destination airport was delayed by more than 24 hours.

20.

The applicant passenger claimed compensation from TAP in the amount of EUR 600 under Article 5(1)(c) of Regulation No 261/2004 in conjunction with Article 7(1)(c) of that regulation. TAP refused to compensate him on the ground that the long delay was caused by ‘extraordinary circumstances’, within the meaning of Article 5(3) of Regulation No 261/2004, which exempted it from the obligation to pay its passengers the compensation due under that regulation. The applicant passenger takes the view that the ‘extraordinary circumstance’ which arose in this case does not justify the fact that his arrival at the destination airport was delayed by more than 24 hours.

21.

Since it has doubts as to the interpretation of EU law, the Tribunal Judicial da Comarca de Lisboa (District Court, Lisbon) decided to stay the proceedings and to refer the following questions to the Court for a preliminary ruling:

22.

The order for reference, dated 21 January 2019, was lodged at the Court Registry on 31 January 2019.

23.

Written observations were lodged by the Portuguese, German, Austrian and Polish Governments and by the European Commission within the period laid down by Article 23 of the Statute of the Court of Justice.

24.

By way of a measure of organisation of procedure dated 8 October 2019, the Court put questions to all the parties and interested persons to be answered in writing. The Court also requested information from the European Aviation Safety Agency (EASA), in accordance with Article 24(2) of the Statute of the Court of Justice, and requested that it attend the hearing. The written observations on the questions put by way of measures of organisation of procedure were lodged within the prescribed period.

25.

At the hearing on 5 December 2019, the legal representatives of TAP, the French, German and Portuguese Governments, the EASA and the Commission submitted observations.

26.

The protection of air passengers in the European Union is covered by a regulation which has the effect of harmonising, to a large extent, the rules on compensation and assistance to passengers in the event of denied boarding and of cancellation or long delay of flights. Regulation No 261/2004 contains provisions setting out the rights of passengers vis-à-vis airlines. Depending on their situation, passengers may be entitled to receive compensation, assistance in the form of reimbursement or re-routing or to receive care offered by the air carrier. That being said, it is the right to compensation in the event of a long delay to the flight – that is, a delay equal to or in excess of three hours – on the basis of Article 7 of that regulation, ( 7 ) which is at the heart of the main proceedings, as stated in the introduction to the present Opinion.

27.

Regulation No 261/2004 also has the effect of harmonising the rules which allow airline companies to be absolved of their liability towards passengers in specific cases. Where an air carrier is in a situation which, theoretically, gives rise to the right to compensation, it may legitimately oppose that obligation on the basis of Article 5(3) of Regulation No 261/2004, provided that it can prove that the cancellation was caused by ‘extraordinary circumstances’ which could not have been avoided even if all reasonable measures had been taken. ( 8 ) It is for the referring court to determine whether that is so in the main proceedings, while also taking into account the Court’s answers to the questions referred for a preliminary ruling.

28.

In adopting a regulation with detailed provisions, the EU legislature chose a legislative instrument which does not require national transposition or implementing measures. ( 9 ) In the same way that the regulation is binding in its entirety and directly applicable in all Member States, the Court’s interpretation of that regulation must be applied by the national courts. In that regard, it is importance to note the significance of the cooperation between the Court of Justice and the national courts, since it has enabled the Court to provide useful clarification on the interpretation of Regulation No 261/2004. ( 10 ) That interaction between them, which has already given rise to extensive case-law, was necessary, primarily because of the lack of clarity in some of the provisions of that regulation, particularly as regards the concept of ‘extraordinary circumstances’, ( 11 ) and the existing legal lacunae. In order to address those shortcomings, the legislature decided to initiate a procedure for the revision of that regulation, which is still ongoing. ( 12 ) It is against that background that it falls, once again, to the Court to take up its leading role in the development of EU law. For my part, in this Opinion, I shall examine the questions referred for a preliminary ruling in the order in which they were asked by the referring court.

29.

By its first question, the referring court asks whether acts of physical assault, such as those described above, committed by a passenger against other passengers and cabin crew members during a flight may be considered as ‘extraordinary circumstances’.

30.

The wording itself of Regulation No 261/2004 contains no legal definition of that concept. However, some guidance is provided in the second sentence of recital 14 of that regulation. Accordingly, such circumstances may arise, inter alia, in the event of ‘security risks’. ( 13 ) The question nevertheless arises as to what security risks may constitute extraordinary circumstances in the specific field of air passenger transport.

31.

In my opinion, examination of that question calls for an interpretation which takes account of the legal framework applicable to the field in question. ( 14 ) Regulation No 261/2004 cannot be interpreted without taking into account the political, socio-economic and technological context in which it was adopted, as well as subsequent relevant regulatory developments. ( 15 ) That approach, which supplements other methods of interpretation recognised by the case-law of the Court, ( 16 ) will enable me to identify the risks connected with air passenger transport currently recognised by the EU legislature. It will also enable the Court to interpret Article 5(3) of Regulation No 261/2004 consistently with other relevant measures, thus helping to ensure the unity of the EU legal order.

32.

It is apparent from an analysis of all the relevant legal measures governing air passenger transport that the EU legislature attaches particular importance to safety, since Regulation No 261/2004 itself provides, in Article 2(j), that passengers may be denied boarding for ‘reasons of … safety or security’. I note that the wording of that provision does not preclude the risk to which it refers from being attributable to the violent behaviour of a passenger.

33.

Mention should also be made of Regulation No 376/2014 on the reporting, analysis and follow-up of occurrences in civil aviation and the related legal measures. Implementing Regulation 2015/1018 lays down a list classifying occurrences which may represent a significant risk to aviation safety and which are to be mandatorily reported by aviation professionals according to Regulation (EU) No 376/2014. Point 6(2) of Annex I to Implementing Regulation 2015/1018 mentions ‘difficulty in controlling intoxicated, violent or unruly passengers’ as an occurrence related to security during the operation of the aircraft. The EU legislation therefore expressly considers that the violent behaviour of a passenger towards other aircraft occupants, such as that which has been found in the main proceedings, constitutes a significant risk which must be reported to the competent authorities.

34.

Regulation 2018/1139 on common rules in the field of civil aviation and establishing a European Union Aviation Safety Agency is also relevant in this context, as it confers a central role on the pilot in command by giving him or her, under point 1.3 of Annex V to that regulation, responsibility for the ‘safety of the aircraft and for the safety of all crew members, passengers and cargo on board’. The provision in point 3(g) of Annex V seems to me to be of particular relevance, given that it states that ‘a pilot in command must take all necessary measures so as to minimise the consequences on the flight of disruptive passenger behaviour’. Point 7.3 of that annex states that, ‘in an emergency situation, which endangers the operation or the safety of the aircraft and/or persons on board’, the pilot in command must take any action he/she considers necessary in the interest of safety. I note that that provision is drafted in sufficiently broad terms to be able to classify the physical assault by one passenger against other persons on board a flight, in a case such as the present one, as a risk to aviation safety.

35.

In international law, mention should be made of the Tokyo Convention, to which all the Member States, but not the European Union, are contracting parties. Although – unlike other instruments of international law governing matters relating to air transport – ( 17 ) that convention is not part of the EU legal order, in so far as there has been no explicit transposition of the convention which would reflect a potential transfer of powers from the Member States to the European Union, ( 18 ) the fact remains that certain legislative parallels reveal a common legal conviction. Therefore, it seems to me that the Tokyo Convention may be used as a reference instrument for the purposes of interpreting EU law. According to Article 1(1) of the Tokyo Convention, it applies to ‘offences against penal law’ and to ‘acts which, whether or not they are offences, may or do jeopardise the safety of the aircraft or of persons or property therein or which jeopardise good order and discipline on board’. Like the abovementioned provisions of Regulation 2018/1139, Article 6(1) of that convention allows the pilot in command of the aircraft to take reasonable measures, including restraint, which are necessary to ‘protect the safety of the aircraft, or of persons or property therein’ when he or she has reasonable grounds to believe ‘that a person has committed, or is about to commit, on board the aircraft, an offence or act contemplated in Article 1, paragraph 1’. ( 19 ) The criteria for applying the Tokyo Convention as a reference instrument for the purposes of interpretation seem to me to have been fulfilled in the present case, given that, with some exceptions, physical assault constitutes a punishable act according to the criminal laws of the EU Member States.

36.

It is apparent from the foregoing that, in so far as EU legislation and international law consider violent passenger behaviour towards other passengers and members of cabin crew, such as that at issue in the main proceedings, to be a significant risk to aviation safety, it cannot automatically be ruled out that the situation described constitutes an ‘extraordinary circumstance’ within the meaning of Article 5(3) of Regulation No 261/2014.

37.

As the Court has already stated in its case-law, ‘security risks’ – like the other circumstances referred to in recital 14 of Regulation No 261/2004 – are not all capable of constituting ‘extraordinary circumstances’ which are grounds for the air carrier’s exemption from liability. ( 20 ) It should be borne in mind that, to the extent that it leads to a derogation from the normal rule, namely the payment of compensation, which serves a consumer protection objective, the concept of ‘extraordinary circumstances’ referred to in Article 5(3) of Regulation No 261/2004 must be interpreted strictly. ( 21 )

38.

According to settled case-law, in order for a situation to be covered by that concept, two cumulative conditions must be fulfilled, namely (a) that the events are not inherent in the normal exercise of the activity of the air carrier concerned and (b) that the events are beyond the air carrier’s actual control. ( 22 ) Assessment on a case-by-case basis is required in order to ascertain whether those criteria have indeed been fulfilled. It is therefore necessary to conduct a rigorous examination of those criteria, taking into account the factual background set out in the order for reference.

39.

It is apparent from an examination of the relevant cases that the first criterion requires that the event in question is not intrinsically, inseparably and typically connected with air passenger transport. In other words, the concept concerned covers events which do not normally take place in the context of the organisation and/or operation of air transport. It therefore covers all events which are not linked to actual air transport operations but which, as specific external circumstances, adversely affect, or even render impossible, the planned execution of those operations.

40.

As a preliminary point, it should be recalled – as obvious as it may seem – that the function of civil air traffic services is to enable the transport of passengers and goods over long distances. The transport of passengers and goods is an important economic activity, carried out primarily by private undertakings, and therefore contributes to the economy of the European Union. By making it easier for European citizens to fly, passenger transport has brought them closer together and enabled them to be better connected to the rest of the world. The abundance of air travel opportunities has enabled many European citizens to travel, study and work in Europe and beyond. Moreover, the number and frequency of flights have grown substantially thanks to the creation of the internal market for aviation, an increasingly competitive environment which has made flying cheaper. ( 23 )

41.

From that point of view, it also seems clear to me that neither the education of, nor the imposition of penalties on, passengers who demonstrate violent behaviour can reasonably be regarded as being part of the functions of civil air traffic services. Although it is true that cabin crew give safety information to passengers before every flight, it is also true that the purpose of that practice is only to ensure the smooth running of the transport operation. Safety instructions are designed to help passengers familiarise themselves with the risks inherent in air transport, namely the risk of injury during take-off or landing, or in the event of turbulence or a drop in cabin pressure, etc. ( 24 )

42.

Those safety instructions do not, however, cover the more general issue of the use of violence in interpersonal relationships, and rightly so, given that that issue goes beyond the context of transport, as I shall explain below. For their part, passengers are required to follow the crew’s instructions. The competence of the cabin crew with regard to the operation of the aircraft and its authority to maintain good order and discipline on board are very rarely called into question by anyone.

43.

As argued by a number of interveners in the present case, the violent behaviour of some passengers towards other passengers and towards cabin crew is not an event that is typical of an air carrier’s operations. Unfortunately for all those involved, a physical assault can occur in any other situation and for a variety of reasons. Some of those reasons may be closely related to the personality of the attacker, while others, such as stress, may be caused by the specific situation in which the attacker finds himself or herself during a flight. ( 25 )

44.

That being said, it must be stated that the order for reference does not contain any details as to the cause of the aggressive behaviour of the passenger in question. For that reason, and since it is impossible to list all the situations which may give rise to the violent behaviour of a passenger on board an aircraft, the Court will have to confine itself to general considerations in its answer to the first question referred for a preliminary ruling.

45.

For the sake of completeness, I would like to emphasise that the fact that isolated cases of physical assault occur sporadically does not seem to me to be sufficient reason in itself to conclude that the use of violence is inherent in the normal exercise of air passenger transport. In that regard, I share the reservations expressed by Advocate General Tanchev in his Opinion in Case C‑501/17, Germanwings, ( 26 ) concerning the argument that the frequency of an event should constitute a limiting or differentiating criterion. I would stress that, leaving aside the questionable validity of that argument, there is nothing to support it in the present case, since all the interveners conclude that the use of violence on board an aircraft is a relatively rare event, or in any case, that it is no more frequent on board an aircraft than anywhere else. ( 27 )

46.

In so far as the use of violence by a passenger against other passengers and/or cabin crew is not what would be considered to be socially acceptable behaviour, and is even punishable under the criminal law of the Member States, it is clearly an event which is outside the realm of air transport. It does not take place in the normal course of the organisation and/or operation of air transport. It may also adversely affect the organisation and/or operation of air transport if that violence is directed against the aircraft’s structure and the staff responsible for its operation. National legislation generally takes that into account by classifying such an act of aggression as an aggravated offence.

47.

It is apparent from the foregoing that the event at issue is not inherent in the normal exercise of the activity of the air carrier concerned.

48.

The second criterion requires that the event in question be beyond the actual control of the air carrier. As set out above, ( 28 ) there may be a number of reasons for an individual’s aggressive behaviour, which makes it almost impossible to anticipate and to respond to it appropriately. Given the unpredictability of violent passenger behaviour and taking into account that that behaviour, as described in the order for reference, is not inherent in air transport, it seems to me to be inappropriate for the air carrier to be given sole responsibility for preventing and suppressing violent incidents on board an aircraft. To the extent that, first, compliance with the rules of civility is required in all everyday situations and, second, cabin crew constitute the principal contact point for the amicable resolution of any dispute between passengers, I consider that each passenger should take responsibility for his or her behaviour and for the consequences which flow therefrom.

49.

I am persuaded by the argument put forward by several of the Member States which submitted observations in this case – in particular the German and Polish Governments – according to which cabin crew members have only very limited means of controlling an aggressive passenger. Indeed, although the pilot in command and cabin crew members may give specific orders to a passenger (for example, urge him or her to calm down, give him or her a warning, allocate a different seat, and so forth) or restrain a passenger in order to ensure the safety of the flight, they cannot control him or her in such a way as to completely exclude any disruptions of the flight by that passenger, since those, as indicated above, are the responsibility of that passenger.

50.

That consideration applies all the more to the prevention of such violent incidents, since, generally, air carriers do not have any information indicating that a passenger will, on board the aircraft, engage in aggressive behaviour which may compromise the safety of a flight. Furthermore, air carriers do not have the right to deny boarding to a passenger who is behaving normally at the time of boarding. However, it must not be forgotten that, where a violent incident occurs after the aircraft has taken off, cabin crew members can no longer adopt preventive measures and the scope of their actions is therefore limited to taking the measures to suppress the incident identified above, within the confined space of an aircraft cabin.

51.

I share the view of the Austrian Government and the Commission that the situation should be assessed in a fundamentally different way if a passenger exhibited behavioural issues before, or even during, boarding, and the air carrier may therefore have had knowledge of those issues. In such a case, it does not seem to me to be justified to exempt the air carrier from liability, allowing it legitimately to rely on extraordinary circumstances if the passenger concerned later proceeded to behave inappropriately or continued to behave in that way. ( 29 ) The interpretation of the aforementioned provisions of EU law and of the Tokyo Convention, which give the pilot in command the power to take the necessary measures to ensure the safety of the flight, ( 30 ) must necessarily incorporate the idea of risk prevention, in so far as that is possible, in order for those provisions to be effective.

52.

In view of the limits which are usually imposed on cabin crew members in terms of the measures they can take to prevent and suppress such risks, disembarking a violent passenger at the nearest accessible airport – as a measure of last resort – does not appear to be an unreasonable option if the pilot in command decides, after careful consideration and taking into account all the circumstances of the case, that continuing the flight in such conditions is impossible without compromising the safety of the aircraft or of the persons on board. Moreover, I would point out that that is precisely what the provisions of Article 6(1)(c) and Article 8(1) of the Tokyo Convention authorise the pilot in command to do when faced with such a situation. ( 31 )

53.

It follows from the foregoing considerations that if, by adopting the measures which they are authorised to take, cabin crew members are unable to calm a passenger, and that passenger compromises the safety of the flight – for example, by threatening the physical safety of the persons on board the aircraft or by harming them – that situation constitutes a circumstance beyond the control of the air carrier for the purposes of the second criterion laid down by the case-law. That is certainly the case in a situation such as that in the main proceedings, where a disruptive passenger bites other passengers and assaults the cabin crew members who were attempting to calm him.

54.

My examination of the facts leads me to conclude that those two criteria, laid down in the case-law for the purpose of establishing the existence of ‘extraordinary circumstances’ within the meaning of Article 5(3) as interpreted in the light of recitals 14 and 15 of Regulation No 261/2004, have been fulfilled in the present case.

55.

On the basis of those considerations, the answer to the first question referred for a preliminary ruling should be that the fact that a passenger, in the course of a flight, bites other passengers and assaults the cabin crew members who were attempting to calm him or her to such an extent as to justify, according to the pilot in command, a diversion to the nearest airport to disembark that passenger and offload his or her luggage for safety reasons, which results in the delayed arrival of the flight at its destination, falls within the concept of ‘extraordinary circumstances’ referred to in Article 5(3) of Regulation No 261/2004.

56.

By its second question referred for a preliminary ruling, the referring court asks, in essence, whether Article 5(3) of Regulation No 261/2004 should be interpreted as meaning that, in order to be exempted from liability to pay the passenger the compensation due under Article 7 of that regulation in the event of a long delay, an air carrier may also rely on extraordinary circumstances which arose not on the flight booked by that passenger, but on the preceding flight, made on the same day and by the same aircraft as that which made the booked flight, as part of the system of aircraft rotation between airports.

57.

In that regard, it is necessary first of all to draw the Court’s attention to the fact that it has already had the opportunity to take a view – albeit only implicitly – on this question of law. Indeed, the Court recognised in Case C‑315/15, Pešková and Peška, ( 32 ) that an extraordinary circumstance, in that instance a collision with birds, could be relied on even though it had not affected the flight booked by the delayed passenger, but a preceding flight made by the same aircraft as part of a scheduled circuit. Similarly, in Case C‑501/17, Germanwings, ( 33 ) the fact that a screw had pierced a tyre of the aircraft used for the flight preceding the delayed flight was considered to be an extraordinary circumstance. It follows that the question referred for a preliminary ruling should be answered in the affirmative on the basis of those judgments.

58.

Should the Court consider that that case-law does not, in itself, provide an adequate response to the question referred for a preliminary ruling, I propose to supplement the reasoning by means of an interpretation of the relevant provisions. That being said, I note that neither the wording nor the spirit and purpose of Article 5(3) of Regulation No 261/2004, interpreted in the light of recital 15 of that regulation, support the conclusion that extraordinary circumstances – such as, in the present case, a violent passenger jeopardising safety on board the aircraft – must directly concern the flight that is ultimately affected (by being delayed or cancelled) as a result of those extraordinary circumstances.

59.

On the contrary, as regards the wording of Article 5(3) of Regulation No 261/2004, an examination of several language versions of that provision leads to the conclusion that a simple causal link between the extraordinary circumstances and the cancellation or delay is sufficient. ( 34 ) That interpretation is confirmed by the wording of recital 15 of that regulation, which makes clear that the cancellation or delay must be caused by the impact of an air traffic management decision in relation to ‘a particular aircraft’ involving ‘one or more flights by that aircraft’. ( 35 ) In other words, what matters is that the causal chain runs all the way to the cancellation or delay in question.

60.

Moreover, it should be noted that, in so far as recital 15 of Regulation No 261/2004 refers to a situation in which multiple flights operated by the air carrier using the same aircraft are affected by the extraordinary circumstances, the legislature appears to have taken into account, inter alia, cases such as that in the main proceedings, where the air carrier has put in place an aircraft rotation system in order to operate a particular route. As several interveners in this case have stated in their observations, it is common practice in the field of air passenger transport to use such a rotation system because of the need to make economically judicious use of aircraft. ( 36 )

61.

First, a broad interpretation of Article 7 of Regulation No 261/2004, which gives passengers the right to receive compensation even if the cancellation or long delay is caused by extraordinary circumstances which arose during a preceding flight, seems to be consistent with the objective pursued by that regulation, which is to ensure a high level of protection for air passengers. As the Court noted in Joined Cases C‑581/10 and C‑629/10, Nelson, ( 37 ) the fixed compensation provided for in the abovementioned article pursues that objective in so far as it enables a loss of time suffered by passengers to be redressed without their having to prove that they have sustained individual damage.

62.

Second, it is clear that imposing liability with no limitation period, based on a simple causal link and without providing for any criteria for remedial action, would be tantamount to disregarding the delicate balance achieved by the EU legislature between the interests of air passengers and those of air carriers in adopting Regulation No 261/2004. The legislature sought to strike a balance between those competing interests by providing that air carriers be exempted from the obligation to pay compensation if they are able to prove that the cancellation or long delay caused by extraordinary circumstances could not have been avoided even if all reasonable measures had been taken. ( 38 )

63.

It follows from the foregoing that there is, in theory, no temporal limit which precludes the application of Article 7 of Regulation No 261/2004 to a situation such as that in the present case, in which an aircraft rotation system is in place, given that that provision requires only that there be a causal link between the extraordinary circumstances which arose during the preceding flight and the cancellation or long delay of the flight booked by the passenger. That being said, I note that, according to the information provided by the referring court, the diversion of the flight from Lisbon to Las Palmas airport following the incident on board was the cause of the delay in boarding the flight on which the applicant passenger was travelling from Fortaleza to Lisbon. Therefore, subject to the factual checks to be carried out by the referring court, it cannot be excluded that Article 7 of Regulation No 261/2004 may be applied in the present case.

64.

Nevertheless, the air carrier may be exempted from the obligation to pay compensation on the basis of Article 5(3) of Regulation No 261/2004 if it is able to prove that the cancellation or long delay caused by extraordinary circumstances could not have been avoided even if all ‘reasonable measures’ had been taken. ( 39 ) The question of whether that condition is satisfied in the present case depends on the scope of that concept of EU law, which is the subject of the third question referred for a preliminary ruling and which will be examined below.

65.

In the light of those considerations, the answer to the second question referred for a preliminary ruling should be that an ‘extraordinary circumstance’ which arises on board an aircraft used in a rotation system justifies, in principle, the air carrier’s exemption from the obligation to pay compensation for cancellations or long delays that occur as a result. The air carrier must, however, be able to prove that it took all economically reasonable measures to avoid the cancellation or long delay in question.

66.

By its third question, the referring court asks, in essence, whether, in the present case, TAP, as air carrier, took all ‘reasonable measures’, within the meaning of Article 5(3) of Regulation No 261/2004. It refers to TAP’s contentions in the main proceedings that the delay in the applicant passenger’s arrival at his final destination could not have been avoided, taking into account the specific features of the situation, which can be summarised as follows: the airline uses a rotation system to fly between Lisbon and Fortaleza; only one aircraft is used for that route; the outward and return flights were delayed; and there is only one flight per day between Lisbon and Oslo.

67.

In that regard, it should be recalled at the outset that the procedure established in Article 267 TFEU is an instrument of cooperation between the Court of Justice and national courts, by means of which the former provides the latter with the interpretation of such EU law as is necessary for them to give judgment in cases upon which they are called to adjudicate. ( 40 ) In accordance with that well-established division of jurisdiction, it is for the national courts to apply EU law in the light of the interpretation given by the Court. Therefore, it seems clear from the wording of the third question that the national court is asking the Court of Justice to rule itself on whether the specific measures of organisation adopted by TAP were ‘reasonable’. The Court must nevertheless limit itself to clarifying the scope of that concept, in the light of the circumstances of the case.

68.

Those preliminary remarks apply a fortiori since it is left to the referring court to apply the provisions of Regulation No 261/2004 after carrying out a detailed assessment of the facts itself, as required by the case-law. ( 41 ) That said, given the very succinct description of the factual background set out in the order for reference, it cannot be ruled out that there are other important aspects to take into consideration in the examination of that question which may escape the Court’s attention due to the absence of necessary information concerning, for example, the logistical, technical and financial resources at the air carrier’s disposal. Consequently, the degree of precision of the guidance that the Court provides to the referring court will depend, to a large extent, on the information collected. That must be kept in mind when determining what is meant by the requirement to ‘take all reasonable measures’ to avoid a long delay in a context such as that examined in the present case.

69.

The Court has interpreted that concept as meaning that, when extraordinary circumstances arise, the air carrier is required to take ‘measures appropriate to the situation’, provided that such measures are ‘technically and economically viable’. ( 42 ) The air carrier must ‘deploy all its resources in terms of staff or equipment and the financial means at its disposal’ without being required to make ‘intolerable sacrifices in the light of the capacities of its undertaking’. ( 43 ) The burden of proof lies with the air carrier, which may be exempted from its liability to passengers only if it is able to show that it took all reasonable measures to avoid or mitigate the damage, or if it is able to prove that it was impossible for it to take such measures.

70.

It must be stated that the case-law cited above imposes, in the interest of consumer protection, particularly strict conditions for exemption, requiring the air carrier to do everything objectively possible with the available resources in order to avoid the cancellation or long delay of a flight. As indicated above, in the absence of comprehensive information enabling the Court to assess the air carrier’s situation, it will be for the referring court to ascertain whether TAP had at its disposal other, more effective means of ensuring that the applicant passenger would arrive at his final destination in Oslo on time. It should be recalled, in that context, that its obligation to transport the passenger requires that the passenger reach his final destination, and not just the place of connection, at the earliest opportunity. ( 44 ) It follows that the air carrier cannot validly argue that it ‘partially fulfilled’ that obligation.

71.

The following elements of interpretation are intended to give the referring court the necessary guidance to enable it to carry out an effective and targeted assessment of the facts.

72.

First of all, it should be taken into account that the longer the period of time that elapses between the event constituting an extraordinary circumstance and the scheduled arrival time at the final destination, the greater the air carrier’s freedom of action. In other words, if the air carrier has enough time, there are normally a number of possible solutions it can implement in order to transport the passenger concerned to his or her final destination. Conversely, there are very limited, if any, options available when time is short. The itinerary of the flight in question must also be taken into account. Where the flight consists of a number of separate legs, as it does in the present case, this does not necessarily mean that, if one leg is delayed, it will lead to a series of setbacks which will subsequently increase the delay. On the contrary, it may open up opportunities for the air carrier, provided that that air carrier has allowed enough reserve time at each stage of the itinerary to be able to implement alternative solutions where necessary.

73.

As the Court recalled in Case C‑94/10, Eglītis and Ratnieks, ( 45 ) a reasonable air carrier organises its resources in good time to provide for some reserve time, so as to be able to implement other solutions. It is therefore crucial that the air carrier organises its itineraries meticulously and rationally in order to prevent problems and inconveniences for passengers, caused by flight cancellations and long delays, in accordance with the objective referred to in recital 12 of Regulation No 261/2004. I share the Portuguese Government’s view that air carriers must not be encouraged to refrain from taking all the measures necessary in order to relinquish their responsibility. Accordingly, the referring court must ascertain whether the air carrier, at the given time, had at its disposal alternative logistical or technical solutions which could have compensated for, or at least considerably reduced, the delay to the flight, such as, for example, using a replacement aircraft, ( 46 ) increasing the speed of the aircraft or transferring the passenger onto other routes, with or without stopovers, operated by the air carrier in question or by other air carriers belonging to the same association (in the present case, ‘Star Alliance’). Having an emergency plan to deal with unforeseen circumstances is all the more important when a rotation system has been implemented, with only one aircraft being used for the transportation of passengers over a considerable distance, as in the present case between Lisbon and Fortaleza. As observed by the Austrian Government, with no resources to support it, a rotation system is vulnerable, as it inevitably leads to a delay in the next flight made by the same aircraft.

74.

The referring court must base its assessment on appropriate evidence, in particular status reports and other analyses produced by the air carrier in relation to the period in question, which will enable it better to understand the rationale behind flight scheduling. From my current perspective, however, I would like to note, as the Portuguese Government has done, that it does not appear that TAP has claimed or proved that it took any measures during the period of time that elapsed between the arrival of the flight in Lisbon, on 22 August 2017, and the boarding of the passenger onto the flight to Oslo, on 23 August 2017. It seems to me to be appropriate to entrust the referring court with the task of challenging the air carrier on this point and examining the reasons why it did not consider alternative arrangements for that last leg of the flight.

75.

In conclusion, I propose that the answer to the third question referred for a preliminary ruling should be that the ‘reasonable measures’ which air carriers are required to take under Article 5(3) of Regulation No 261/2004 must be intended to avoid the typical consequences of extraordinary circumstances, namely cancellations and long delays to arrival times. The measures which, in this context, may specifically be required of air carriers to avoid the consequences of an extraordinary circumstance, namely, in the present case, a long delay, must be assessed on a case-by-case basis.

76.

The referring court must ascertain whether the carrier had organised its resources in good time to provide for sufficient reserve time to be able to implement alternative logistical or technical solutions to compensate for, or at least considerably reduce, the delay to the flight, such as, for example, using a replacement aircraft, increasing the speed of the aircraft or transferring the passenger onto other routes, with or without stopovers, operated by the air carrier in question or by other air carriers. The referring court must base its assessment on appropriate evidence, including status reports and other analyses produced by the air carrier, which will enable it better to understand the rationale behind flight scheduling.

77.

In the light of the foregoing, I propose that the Court answer the questions referred for a preliminary ruling by the Tribunal Judicial da Comarca de Lisboa (District Court, Lisbon, Portugal) as follows: