Clearing clouds of uncertainty—a principled approach to determining what qualifies as an ‘accident’ under the Montreal Convention

Abstract

The revival of international air travel in the wake of the receding COVID-19 pandemic has refocused the spotlight on the inherent hazards of carriage by air. From a legal perspective, the focal issue is whether any of those air travel-related incidents that may result in passenger death or bodily injury are compensable accidents. This article examines the meaning and scope of the term ‘accident’ under Article 17(1) of the 1999 Montreal Convention (MC99)—the exclusive regime for air carrier liability within international air transportation. The term ‘accident’ is a condition precedent to air carrier liability but has been left undefined by the drafters of MC99, leaving it to national courts to interpret its meaning. Accordingly, the article utilizes a doctrinal and normative methodology to review a select body of case law drawn primarily from common law jurisdictions. It proceeds to identify a set of ten principles that would guide future courts to ascertain whether an alleged event qualifies as an ‘accident’ consistently and predictably. The article also discusses the controversial interpretation of ‘accident’ by the Court of Justice of the European Union, signaling judicial discord, and sheds light on the consequent implications, especially in regard to MC99’s pursuit of global uniformity and achieving a fair balance of interests between passengers and air carriers.

I. Introduction

Four years following the outbreak of the coronavirus pandemic and the highly anticipated reopening of international borders, 2023 was a year in which global air transportation nearly returned to its pre-pandemic pace of activity.¹ The International Air Transportation Association projects that the number of air passengers will fully recover to 2019 levels by the end of 2024.² As global passenger traffic continues to surge and operating profits reach record-breaking levels,³ so do the risks inherent in air travel. News outlets provide periodic doses of harrowing incidents, ranging from flights hit by severe, bone-breaking turbulence and blown-out portions of the fuselage to passengers attempting to open an aircraft’s emergency exit door mid-flight.⁴ Such newsworthy events and other unreported air travel-related incidents recast the spotlight on air carrier liability and the availability of damages awards.

Air carrier liability in respect of claims arising out of or in the course of international carriage by air is governed by the Convention for the Unification of Certain Rules for International Carriage by Air, signed in Montreal in 1999 (MC99).⁵ Chapter III of MC99 sets out three distinct heads of air carrier liability: (i) personal injury or wrongful death; (ii) baggage or goods loss, destruction, or damage; and (iii) damage occasioned by delay. Article 17(1) establishes the substantive conditions for personal injury and wrongful death claims against air carriers:

The carrier is liable for damage sustained in case of death or bodily injury of a passenger upon condition only that the accident which caused the death or injury took place on board the aircraft or in the course of any of the operations of embarking or disembarking.

The italicized words in the provision above have been the subject of much litigation and academic discussion, largely because MC99 itself does not provide a working definition for these rather vague concepts. This difficult task has been assigned to national courts of Signatory States. Judicial interpretation of Article 17(1) has produced a substantial body of case law, which, as will be presented in this article, has not been entirely consistent and in line with MC99’s mandate of global uniformity.⁶ Accordingly, the principal research question is whether a uniform and coherent set of legal principles could be distilled from the repository of cases interpreting the term ‘accident’ under Article 17(1).⁷

The article adopts a doctrinal and normative methodology to answer the aforementioned research question. The case law examined for present purposes is selectively drawn from decisions rendered by senior courts in the USA, England, Australia, and the European Union (EU)—namely, the Court of Justice of the European Union (CJEU). It will become apparent to the reader that courts from common law jurisdictions have had a pivotal role in developing much of the long-standing, orthodox analysis in this area, whereas the CJEU’s nascent case law represents a more liberal and non-conformist approach. The implications stemming from this judicial divergence will be explored. For the normative analysis, the article measures the extent to which the parallel judicial interpretations of the term ‘accident’ under Article 17(1) accord with the policy considerations underpinning MC99 and, thus, which of the two ought to be followed. The third recital of MC99 states that the State parties ‘[recognize] the importance of ensuring protection of the interests of consumers in international carriage by air and the need for equitable compensation based on the principle of restitution’. This policy is reflected in Article 21,⁸ which lays out a passenger-friendly, two-tiered liability system: for Article 17 claims under 128,821 special drawing rights⁹ (approximately US $172,370), the air carrier is held strictly liable, with the only defence being contributory negligence. For claims over this ceiling, a carrier may avoid liability if it can show that its negligence or wrongful act did not cause the damage or that the accident occurred because of events beyond the carrier’s control.

On the other hand, the fifth recital of MC99 states that State parties are convinced that ‘collective State action for further harmonisation and codification of certain rules governing international transport by air through a new Convention is the most adequate means of achieving an equitable balance of interests’ (emphasis added). Some of the notable airline-friendly provisions include the possibility of total or partial exoneration from liability by demonstrating the plaintiff’s contributory negligence (Article 20), the explicit exclusion of exemplary (that is, punitive) damages (Article 29), and a short limitation period of two years in which to bring an action (Article 35). Thus, MC99 strives to create a delicate balance of protection between the interests of airline passengers and the interests of air carriers.¹⁰

The present article is structured as follows. Section II, following this introduction, outlines the legal framework of MC99. The next section revisits the seminal decision in Air France v Saks (Saks),¹¹ which was the first attempt by the US Supreme Court to formulate a uniform definition of ‘accident’. Section IV discusses issues concerning the scope of the term ‘accident’ within the meaning of Article 17(1). Section V examines the merits and demerits of the CJEU’s emerging case law. Section VI concludes.

II. Legal framework of air carrier liability under MC99

The overarching purpose of MC99 was to respond to the urgent need of the international community to modernize and consolidate the Convention for the Unification of Certain Rules Relating to International Carriage by Air (WC29), signed in Warsaw in 1929—MC99’s long-standing predecessor.¹² Briefly, WC29 and its amending protocols and supplementary instruments evolved into a complex, fragmented, and opaque legal framework whose usefulness for the travelling public became a matter of growing concern, prompting the international community to restore legal certainty and uniformity.¹³ At the Diplomatic Conference, MC99 was celebrated as a modernized legal framework destined to serve the objectives of the international aviation community in the ‘new millennium’.¹⁴

Notwithstanding the globally coordinated efforts in adopting a new international instrument, the final text of MC99 retained, almost verbatim, the substantive provisions regulating air carrier liability contained in WC29. Article 17 of WC29, which governs liability for personal injuries and wrongful death, states:

The carrier is liable for damage sustained in the event of the death or wounding of a passenger or any other bodily injury suffered by a passenger, if the accident which caused the damage so sustained took place on board the aircraft or in the course of any of the operations of embarking or disembarking.

Accordingly, both Article 17(1) of MC99 and Article 17 of WC29 prescribe three substantive preconditions for recovery; the onus is on the plaintiff to demonstrate that: (i) an ‘accident’ occurred; (ii) which proximately caused a passenger’s death or bodily injury; and (iii) which took place either on board the aircraft or while embarking or disembarking.¹⁵ Importantly, the Conventions make clear that no liability for death or bodily injury will arise unless such damage was caused by an ‘accident’. However, in neither treaty did the drafters proffer a definition of the condition precedent to liability: ‘accident’.

When considering the term ‘accident’ or any other undefined concept in MC99, national courts must have regard to general rules of interpretation laid down in Article 31 of the 1969 Vienna Convention on the Law of Treaties (VCLT). Article 31 prescribes, in relevant part that:

(1) A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in light of its object and purpose.

(2) …

(3) There shall be taken into account, together with the context:

 …

 (b) any subsequent practice in the application of the treaty which establishes the agreement of the parties regarding its interpretation (emphasis added).

In light of the provision above, courts of signatory States should be mindful of two critical signposts when interpreting Article 17(1). First, the basic concepts adopted for establishing air carrier liability should be interpreted autonomously,¹⁶ in line with the overall scheme of MC99 and its very nature as an international trade law convention. For example, Article 17(1) omits any requirement of negligence or fault for an incident to qualify as an ‘accident’.¹⁷ Therefore, the concepts of equity, fault, reasonable care, or negligence on the part of the air carrier, as understood in the contexts of national legal systems, have no role to play.¹⁸ Rather, the inquiry should be directed at whether the bodily injury or death was caused by something having the characteristics of an ‘accident’ within the meaning of MC99. Second, national courts should try to adopt a uniform interpretation of the Convention’s provisions. In this endeavour, assistance can and should be sought from relevant court decisions in other signatory States; however, the weight to be given to these decisions will depend on the standing of the court and the quality of its legal analysis.¹⁹

It bears emphasizing from the outset that the cardinal purpose of MC99 is to achieve uniformity of rules governing claims that arise out of international air transportation. In order to achieve this goal, MC99 fashioned a comprehensive liability scheme designed to be the sole avenue for relief for injuries suffered during the course of international travel.²⁰ This system protects air carriers against catastrophic liability by establishing monetary caps on awards and restricting the types of claims that may be brought against air carriers while accommodating the interests of injured passengers by creating a presumption of liability against the carrier. As mentioned above, MC99 strives to accommodate or balance the interests of passengers seeking recovery for personal injuries and the interests of air carriers seeking to limit potential liability. Thus, the remedy provided in Article 17(1) is exclusive in the sense that no other domestic law remedy (for example, for want of reasonable care or negligence) is available to a passenger who sustains bodily injury or dies in the course of international carriage but has failed to satisfy the preconditions for invoking air carrier liability under Article 17(1).²¹

Lastly, it is worth noting that interpretations of WC29 have a degree of authoritative or precedential value in interpreting parallel provisions of MC99 that are substantively similar (for example, Article 17 of WC29 and Article 17(1) of MC99).²² Courts of signatory States have explicitly recognized that the case law developed under MC29 is vitally important to understanding the meaning and language of MC99.²³

III. The landmark case of Air France v Saks: towards uniformity

The procedural history of Saks illustrates the disunity among US Circuit Courts in adopting a consistent interpretation of the term ‘accident’ within the meaning of Article 17 of WC29. But first, let us examine the facts: while the aircraft in question was in routine descent for landing, the plaintiff experienced severe pain and pressure in her left ear, which unfortunately developed into permanent loss of hearing. The issue for determination was whether the alleged injury proximately caused during normal operation of a properly functioning aircraft on an otherwise uneventful and ordinary flight constituted an ‘accident’. The airline contended that the normal operations of a standard pressurization system could not qualify as an Article 17 ‘accident’. The District Court agreed; it followed a line of authority out of the Third Circuit in which ‘accident’ was defined as an ‘unusual or unexpected happening’ triggered by some external event.²⁴ The plaintiff had failed to adduce evidence establishing abnormality or malfunction in the operation of the aircraft.

On appeal, the majority of the Court of Appeals, Ninth Circuit, rejected the lower court’s reasoning. It held that demonstrating abnormality or malfunction in the aircraft’s operation was not a prerequisite to establishing liability under Article 17. Rather, according to the majority’s view, the proper definition of ‘accident’ was ‘an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft received substantial damage’.²⁵ Thus, under this broader interpretation, the term ‘accident’ encompassed all risks inherent in air travel, including routine cabin pressurization changes.²⁶ This conflict among Circuit Courts prompted the US Supreme Court to grant certiorari and restore clarity in this contentious area.

The Supreme Court reversed the Ninth Circuit’s decision, ruling that the plaintiff’s deafness resulting from the normal operation of the aircraft’s pressurization system was not an ‘accident’ within the meaning of Article 17 because it was the result of the passenger’s own internal reaction to the usual and expected depressurization of the aircraft during landing.²⁷ To reach this conclusion, the court thoughtfully considered the text of WC29, along with the negotiation history of the treaty, the conduct of the parties to the Convention, and the weight of precedent in foreign and US courts.

Regarding the text of WC29 and the context in which the written words were used, the Supreme Court read Article 17 in conjunction with Article 18, which contains parallel provisions regarding liability for damage to cargo.²⁸ Article 17 imposed liability for passenger injuries or death caused by an ‘accident’. Conversely, Article 18 imposed liability for damage to any checked baggage or goods caused by an ‘occurrence’ during air transportation. This difference in language implies that the terms ‘accident’ and ‘occurrence’ were intended not to be treated as synonymous, with ‘accident’ indicating a more stringent standard of liability for passenger injury and death, unlike ‘occurrence’, which suggests a lower liability threshold. The language of WC29 accordingly questions the opinion of the Ninth Circuit that ‘accident’ means ‘occurrence’.

Next, the Supreme Court noted that the text of Article 17 explicitly refers to an accident that caused the passenger’s injury and not to an accident that is the passenger’s injury.²⁹ In the context of legal liabilities, the court stressed the significance of differentiating instances in which the term ‘accident’ is used to denote both the cause and effect from those in which it merely denotes the effect apart from the cause.³⁰ The drafters of WC29 appear to have distinguished between cause and effect by unequivocally specifying that air carrier liability under Article 17 would be imposed only if an accident caused the passenger’s bodily injury or death. Thus, such phraseology implies that the cause of the injury must satisfy the definition of ‘accident’ rather than the occurrence of the injury alone, further supporting the court’s attempt to limit air carriers’ exposure to liability. Moreover, the Supreme Court observed that in French case law, the legal meaning of ‘accident’ may either refer to the event of a person’s injury or describe a cause of injury, thus paralleling the common law understanding.³¹

On account of the above analysis, the Supreme Court identified the differentiating characteristic as the ‘unexpected or unusual’ nature of accidents, as opposed to the typicality of occurrences.³² Furthermore, the court recognized that while ‘accident’ may be interpreted broadly, it would not extend the term to cover routine travel procedures that produce injury due to the peculiar internal condition of a passenger.³³ Thus, Saks is the leading authority for the proposition that air carrier liability under Article 17 of WC29 arises if a passenger’s injury or death is caused by an ‘unexpected or unusual event or happening that is external to the passenger’ and recovery would be denied if the harm resulted from the passenger’s own ‘internal reaction to the usual, normal and expected operation of the aircraft’.³⁴

Moreover, the Supreme Court in Saks appended two practical directions to guide future courts. First, it stressed that the proposed definition should ‘be flexibly applied after assessment of all the circumstances surrounding a passenger’s injuries’.³⁵ Second, it cautioned that ‘where there is contradictory evidence, it is for the trier of fact to decide whether an accident as here defined caused the passenger’s injury’.³⁶

The Saks test is doctrinally sound to the extent that the Supreme Court did not consider sources outside WC29 to interpret the word ‘accident’ and formulated a definition that was consistent with that accepted in foreign jurisdictions as prescribed by Article 31 of the VCLT.³⁷ As a matter of policy, the ‘unexpected or unusual’ criterion and the ‘externality’ requirement are arguably balanced; they are not overly broad, enabling recovery for all risks inherent in air travel at the expense of carriers. Nor are they too technical and restrictive, precluding bona fide personal injury or wrongful death claims. It is submitted that the Supreme Court’s reasoning in Saks reflects the changing social perceptions of the time—between WC29 and MC99—that demanded a readjustment of the allocation of risk between air carriers and passengers.³⁸

The definition of ‘accident’ set forth in Saks has been endorsed by senior courts and tribunals in several Signatory States, including Australia,³⁹ Canada,⁴⁰ France,⁴¹ Germany,⁴² India,⁴³ the United Arab Emirates,⁴⁴ and the United Kingdom.⁴⁵ Furthermore, the decision on the part of the drafters of MC99 not to include a concrete definition of the term ‘accident’ within Article 17(1) and the position of the delegates at the Diplomatic Conference not to interfere with the case law concerning air carrier liability under WC29 suggest tacit approval of the Saks test. It is worth noting that insurance underwriters for major airlines have also incorporated the Saks formulation, or a modified version of it, within their travel insurance policies.⁴⁶ Notwithstanding this seemingly wide acceptance, the Supreme Court in Saks left a number of critical issues unaddressed, and subsequent courts struggled to apply the language employed in the Saks test. Accordingly, the next section examines those issues that have confronted courts applying the Saks test on what constitutes an ‘accident’.

IV. Delineating the scope of the notion ‘accident’

The Supreme Court in Saks attempted to resolve the conflict among US courts by furnishing a uniform standard, requiring an unusual or unexpected event that was external to the passenger to cause the requisite ‘accident’. However, since that seminal decision, courts applying the language of Saks diverged on a number of critical issues that the Supreme Court had left open. This section discusses three interrelated issues that have a direct bearing on the scope and meaning of ‘accident’ within Article 17(1) of MC99: (i) from whose perspective the ‘unexpected or unusual’ quality of an event should be determined; (ii) the nature of the unusual or unexpected causal event; and (iii) the nexus between the injury-causing event and the operation of the aircraft.

1. Standard for assessing ‘unexpected or unusual’

The question of from whose perspective the ‘unexpected or unusual’ characteristic of an event was to be determined did not arise in Saks; the plaintiff had accepted the normality of the external event.⁴⁷ Victims of aviation-related accidents would naturally advocate for a subjective assessment—that is, that the quality of the injury-causing event should be considered from their viewpoint. However, there is no explicit authoritative support for adopting a subjective inquiry.⁴⁸ Furthermore, on this particular issue, the CJEU has firmly rejected a subjective assessment because it could lead to a ‘paradoxical result’ if the same event were classified as ‘unexpected’ (or, in the words of the CJEU, ‘unforeseen’) and therefore, as an ‘accident’ for certain passengers, but not others.⁴⁹ Moreover, the CJEU has cautioned that a purely subjective approach could extend the notion of ‘accident’ in an unreasonable manner to the detriment of air carriers.⁵⁰

Recently, the US Court of Appeals, First Circuit, addressed the problem of perspective in Moore v British Airways Plc (Moore).⁵¹ The plaintiff arrived at London Heathrow Airport on a flight from Boston operated by the defendant airline. The passengers were instructed to exit the aircraft via a mobile staircase because the jet bridge was inoperable at the time—a common practice followed among air carriers. The plaintiff descended over 20 steps carrying two pieces of hand baggage. Upon reaching the bottom step, she lost her balance, fell, and injured her ankles. Evidence showed that the riser height of the bottom step (that is, the distance between that step and the ground) was 13 inches, while the height of the other steps was 7.4 inches. The plaintiff alleged that this excessive riser height difference exposed her to a misstep hazard and caused her to take an ‘air step’, resulting in her injuries.

After pre-trial discovery, the defendant moved for summary judgment, arguing that the plaintiff’s injuries did not result from an ‘accident’ within the meaning of MC99. The District Court granted the motion, and the plaintiff subsequently appealed. On appeal, the First Circuit had to determine whether using a mobile staircase under the circumstances was an event that may constitute an Article 17(1) ‘accident’. The court applied the Saks formulation and noted that the words ‘unexpected’ and ‘unusual’ were not entirely congruent and should be construed according to their ordinary meaning.⁵²

The First Circuit accepted the defendant’s evidence that the riser height of the bottom step was not ‘unusual’ in light of industry-wide practices. However, whether the height difference of the staircase’s bottom step was ‘unexpected’ proved problematic since Saks does not proffer guidance on the proper perspective from which to ascertain whether or not a given event was expected. On the latter issue, the court concluded that whether an event was unexpected under the definition of ‘accident’ set forth in Saks should be judged from the ‘perspective of a reasonable passenger with ordinary experience in commercial air travel’.⁵³ In the court’s view, this objective approach finds support in the text of MC99, its objects and purposes, and the approach adopted by other US courts and foreign courts.⁵⁴

The First Circuit applied the objective standard and held that there was sufficient evidence for a reasonable jury to find that the plaintiff’s injuries were caused by an ‘accident’ within the meaning of Article 17(1). Equally, the court also found that, on account of the evidence submitted by the defendant, a jury may be persuaded that an ordinary, reasonable passenger would share the perceptions of the flight crew, in that nothing about the use of the staircase in question could be said to be unexpected. Thus, in light of the conflicting evidence, the court concluded that the District Court erred in granting summary judgment because there was a genuine issue of material fact as to whether a reasonable passenger with ordinary travel experience would have expected to disembark on a mobile staircase in which the bottom step had a greater riser height than the other steps.⁵⁵

At first sight, the First Circuit’s reasoning in Moore seems sound and well-supported;⁵⁶ however, a closer reading of the opinion reveals critical flaws in the court’s proposition. The assertion that an objective analysis should be adopted to determine whether a given event was ‘unexpected’, as opposed to the subjective expectations of the injured passenger, promotes certainty and strikes a fair balance between the parties’ competing interests.⁵⁷ However, at a practical level, the First Circuit’s ‘ordinary, reasonable passenger’ standard is conceptually vague and open to various interpretations and, thus, could lead to unpredictable outcomes depending on the jurisdiction. One commentator has also noted that the qualification ‘with ordinary travel experience’ is inherently ‘classist’ for it fails to account for the inexperience of first-time flyers.⁵⁸ Another latent issue with the First Circuit’s reasoning in Moore is that in so far as the notions of ‘ordinary’ and ‘reasonable passenger’ carry common law connotations, they corrode the autonomy of MC99’s concepts and, thus, should not be accepted.⁵⁹

For the above reasons, it is submitted that the appropriate standard of analysis is to be found in an overlooked opinion of Ashley AJA in the case of Qantas Airways Ltd v Povey.⁶⁰ There, his honour addressed the issue of unexpectedness as follows:

[The] characterisation of an event as unexpected or unusual does not involve consideration particularly from the perspective of the airline or the passenger(s); nor, a fortiori, particularly from the perspective of a reasonably careful airline operator or a reasonable passenger in all the circumstances. The latter formulations, in any event, would introduce notions of domestic tort law; and for that reason. …I would not accept their application. Rather…the question whether an event is to be so characterized is to be answered from the perspective of a disinterested bystander who is apprised of all relevant circumstances.⁶¹

Ashley AJA was alluding to the adoption of a holistic, totality-of-the-circumstances approach to the ‘accident’ inquiry.⁶² Such an approach avoids the risk that what is unexpected or unusual would be determined by reference simply to the different sectional interests of the airline or passenger. But it does not mean that, as his Honour clarified, in a particular case, the circumstances of an individual passenger may not be relevant as part of the factual matrix in which the event alleged to constitute an accident falls to be considered.⁶³ Neither does it exclude from consideration the perspective of a particular airline defendant or airline industry practice.⁶⁴ Additionally, the holistic approach is consistent with, and adds substance and clarity to, the US Supreme Court’s instructions in Saks that the ‘accident’ inquiry should be flexible and fact-intensive. More importantly, the holistic approach serves the stated aim of MC99: to provide a uniform, balanced regime that accords equal deference to consumer protection and the airline industry.

The proposed holistic, totality-of-the-circumstances approach raises a contentious, albeit practically significant, issue of whether industry standards and practices should be relevant to the ‘accident’ inquiry. The extant case law suggests that what constitutes an unexpected or unusual event is often measured against applicable operational manuals and industry standards governing the complained of issue. Two cases illustrate the prevailing judicial approach.⁶⁵

The first is Fulop v Malev Hungarian Airlines.⁶⁶ Here, a passenger had a heart attack shortly after his flight departed from Budapest to New York. Contrary to established airline procedures, the crew decided not to divert the flight after consulting a doctor onboard. The District Court denied the airline’s motion for summary judgment with respect to the plaintiff’s Article 17 claim under WC29, allowing for the possibility that an airline’s failure to abide by its own procedures concerning flight diversion in response to a medical emergency could constitute an ‘accident’ under certain circumstances.⁶⁷ The court reasoned that ‘the ordinary traveller reasonably would expect that…in handling life-threatening exigencies, airlines…would be particularly scrupulous and exacting in complying with their own industry norms, internal policies and procedures, and general standard of care’.⁶⁸ Accordingly, the court concluded, an airline’s ‘alleged deviation from its own rules and standards that were in place to deal with passengers stricken by medical emergencies may be sufficient to support a determination that such an event…was unusual or unexpected, and thus an accident within Sak’s interpretation of [WC29’s] Article 17’.⁶⁹

The second case of the pair is the CJEU’s judgment in YL v Altenrhein Luftfahrt GmbH.⁷⁰ The Austrian Supreme Court sought a preliminary ruling on the interpretation of the term ‘accident’ within the meaning of Article 17(1) of MC99, where the claim was brought by the plaintiff alleging to have suffered a spinal disc injury as a result of a ‘hard’ landing. Importantly, however, after examining the flight data recorder, it was determined that the landing was within the normal operating range as set out in the flight manual of the aircraft in question, and no pilot error was found.⁷¹ The CJEU rejected the contention that whether an event was ‘unforeseen’ or, in the language of Saks, ‘unexpected’, to constitute an Article 17(1) ‘accident’ should be determined solely from the perspective of the passenger concerned.⁷² Instead, the CJEU endorsed an objective analysis concluding that, under the facts of the present case, there was no ‘accident’ because the air carrier had complied with the applicable aviation safety regulations, hard landings were considered safer due to the mountainous terrain in which the airport in question was situated, and there was no demonstrable pilot error.⁷³

Critics argue that linking the ‘unexpected or unusual event’ of the Saks definition to industry standards and practices prevailing at the time carries the risk of importing domestic notions of negligence and fault into Article 17(1). As discussed above, Article 17(1) does not require proof of fault for establishing liability. The question of carrier fault comes into play once liability under Article 17(1) has been established by reason of Article 21 of MC99.⁷⁴ Although this concern is warranted in light of safeguarding the integrity of MC99, there should be little objection in so far as industry standards and practices are utilized to assess the nature of the alleged accident—that is, whether the bodily injury or death has a discernible relation to the abnormal or unusual operation of the aircraft or conduct of crew members.⁷⁵ Stated differently, analysing the conduct of the air carrier or crew members in an accident-centric way rather than a tort-centric way (that is, the degree of care exercised) by reference to contemporary industry standards and practices would accord with the balance of interests mandated by MC99. Furthermore, enabling air carriers to self-regulate their operational risks would not necessarily provide them with unbridled immunity, barring bona fide personal injury claims, as evidenced by existing case law in which departures from industry standards and practices were asserted to support a finding of an ‘accident’ within the meaning of Article 17 of WC29/MC99.⁷⁶ Thus, it is submitted that industry standards and practices should not be given dispositive weight but should be used as analytical tools when determining whether the alleged injury-causing event was ‘unexpected or unusual’.⁷⁷

2. The event/non-event conundrum

Some have interpreted the language of Saks—‘an event or happening’—as implying a distinction between action and inaction in the sense of an affirmative act on the part of the air carrier or some person other than the passenger, as opposed to a failure to carry out one or more acts, whether requested or not.⁷⁸ This contention has raised the issue of whether an ‘event or happening’ could be constituted by an omission to act. The leading authority on this issue is the Australian case Povey v Qantas Airways Ltd (Povey).⁷⁹ The case involved a claim by a passenger alleging he had suffered from deep vein thrombosis (DVT) during the course of, or following, a return flight from Sydney to London ‘caused by the conditions of and procedures relating to passenger travel upon the flights’.⁸⁰ Specifically, the plaintiff claimed, inter alia, that not being provided with any information or warning about the risk of DVT or the measures he could have taken to reduce such risk (that is, a failure to warn) amounted to an ‘accident’.⁸¹ On that latter point, Ashley AJA, in the Court of Appeal of Victoria, concluded, after an extensive review of the relevant authorities, that ‘a bare failure to warn or advise, unaccompanied by other circumstances, is unequivocally inaction, and not “accident”…as an unexpected or unusual event’.⁸²

On appeal, the issue before the High Court of Australia was whether flight conditions and/or a carrier’s failure to warn passengers of precautions they could take to avoid DVT could constitute an ‘accident’ within the meaning of Article 17 of WC29. The plurality (Gleeson CJ, Gummow, Hayne and Heydon JJ) clarified that the concept of ‘accident’ should not be overrefined; it invites two questions: first, what happened on board (or during embarking or disembarking) that caused the injury of which the complaint is made, and second, whether what happened was unusual or unexpected.⁸³ According to the court, a mere allegation that while on board or in the course of embarking or disembarking, a passenger sustained ‘some adverse physiological change’ does not identify the occurrence of an accident.⁸⁴ The plurality emphasized that it was central to the passenger’s cause that nothing had happened on board that was out of the ordinary in any way, nor were flight conditions unusual or unexpected.⁸⁵

Thus, the development of DVT during a flight that was otherwise operating under normal conditions was no more than an internal physiological change, for it lacked the required externality (of an unusual, unexpected kind) to qualify as an ‘accident’ within the meaning of Article 17. Furthermore, the plurality noted that the passenger’s allegations in substance do no more than state a failure to warn of a hazard from the long haul of flying in otherwise standard conditions. This failure was not an ‘accident’ on board the aircraft. The plurality observed that

reference to failure is unhelpful because it diverts attention from what it is that happened on board to what might have, could have, or perhaps should have happened there and why that should be so. If…it is appropriate to ask ‘what happened on board?’ the answer in this case is that the [passenger] alleged that nothing unexpected or unusual happened there.⁸⁶

Three important observations may be made with respect to the High Court’s decision in Povey. First, the case reinforces the required ‘externality’ of the causal event (of an unusual, unexpected kind) as distinct from the internal bodily reaction to usual or expected procedures or environment. The appellate court correctly rejected the passenger’s contention that the cramped seating arrangements in the economy class were a causative link in the onset of DVT. However, it should be clarified that the ‘externality’ criterion does not require the plaintiff to establish the precise cause of the injury-causing event or even show that the causal event occurred independently of anything done or omitted by the passenger.⁸⁷ On this last point, Article 20 of MC99 expressly acknowledges that a plaintiff may be able to recover, notwithstanding that the damage was ‘caused or contributed to by the negligence’ of the injured passenger. MC99, therefore, contemplates that a passenger may sustain an ‘accident’, within the meaning of Article 17(1), notwithstanding that he or she may have done or omitted to do something that contributed to the event causing the injury.⁸⁸ Thus, it would be sufficient for a plaintiff to show that the causal event was an unexpected or unusual happening physically external to the passenger.⁸⁹

Second, the plurality of the High Court opined that where the injury-causing event is described as inaction or a failure to do something, the absence of action will not amount to an event unless it can be shown to be an omission by reference to some legal standard requiring action.⁹⁰ In Povey, the description of what happened as a ‘failure’ without reference to some standard of legal behaviour, either imposed by the regulatory authority or adopted by airlines, was no more than an assertion that there was no warning. It is worth noting that, as discussed above, a departure from industry standards would not be dispositive of the issue but would be part of the factual matrix in which the event said to constitute an accident falls to be considered.

Third, both the High Court and the Court of Appeal in Victoria recognized that a failure to act might result in an ‘accident’ or form part of a series of acts and omissions that together constitute an ‘accident’.⁹¹ In such circumstances, distinguishing between acts and omissions may be difficult, if not dubious. The US Supreme Court’s judgment in Olympic Airways v Husain (Husain) is a case in point.⁹² The plaintiff and her husband, who had chronic asthma, boarded a flight from Athens to San Francisco operated by the defendant airline. Despite requesting non-smoking seats, they were seated just three rows away from the smoking section. The plaintiff informed a flight attendant of her husband’s allergy to smoke and repeatedly asked that he be seated further away, but the attendant falsely claimed the flight was full and refused to assist.

At trial, the flight attendant’s refusal to assist was deemed an ‘accident’ under Article 17 of WC29 as it was external to the passenger and, because it was in ‘blatant disregard of industry standards and airline policies,’ was not expected or usual.⁹³ The decision was affirmed on appeal and granted certiorari by the US Supreme Court. The principal issue before the Supreme Court was whether a carrier’s unusual and unexpected refusal to assist a passenger with a known medical condition was a link in the chain of causation resulting in that passenger’s pre-existing ailment being aggravated by exposure to a normal condition in the aircraft cabin. The majority held that the rejection of an explicit request for assistance, which they framed as a ‘failure to act’, would be an ‘event’ or ‘happening’ under the ordinary and usual definitions of these terms and rejected the contention that a flight attendant’s conduct could only constitute an ‘accident’ if it were an affirmative act.⁹⁴ On the other hand, Scalia J, who delivered the dissenting opinion, interpreted the majority’s holding that ‘mere inaction’, like the flight attendant’s refusal to reseat the passenger in the face of a request for assistance, can constitute an ‘accident’ within the meaning of WC29.⁹⁵

Senior courts in other signatory States did not question the outcome in Husain, but the facts demonstrate that the distinction between acts and omissions can be dubious in some circumstances. Nonetheless, there were peculiar features about the confrontation between the plaintiff, her asthmatic husband, and the flight attendant—a series of acts and omissions—that arguably lifted this case from classification as a ‘non-event’ into classification as an unexpected or unusual event and hence an ‘accident’.⁹⁶ Moreover, it is worth noting that the minority judges in Husain recognized how affirmative and unusual action by flight crew could change an omission to act (or ‘non-event’) into an ‘event’. They favoured remanding the proceedings to the District Court to consider whether the flight attendant’s misrepresentation about the aircraft being full, independent of any failure to reseat the passenger, was an ‘accident that caused [his] death’.⁹⁷

The English case, Labbadia v Alitalià Societa Aerea Italiana SpA, neatly illustrates the application of the principles discussed thus far.⁹⁸ The flight in question landed in poor weather conditions; snow was still falling as the plaintiff and other passengers were instructed to disembark from the rear of the aircraft. The plaintiff slipped and fell headfirst down the metal aircraft steps, which were not protected by a canopy. He sustained serious injuries that required hospitalization and operative treatment, followed by several weeks of rehabilitation. The trial court had to determine whether the plaintiff’s injuries had been caused by an ‘accident’ while disembarking the aircraft pursuant to Article 17(1).

The trial court followed the line of English authority affirming the Saks test and found in favour of the plaintiff.⁹⁹ The judge held that the use of stairs without a canopy, under the circumstances, was not a ‘non-event’.¹⁰⁰ It required a positive decision on the part of airport personnel to use stairs either with or without a canopy.¹⁰¹ In bad weather conditions, the airport’s operating procedure was to use stairs with a canopy ‘where possible’.¹⁰² Thus, the plaintiff’s fall was directly caused by acts and omissions by airport personnel, which was an unusual or unexpected event external to him. The judge rejected the defendant’s contention that the fall was a ‘reaction to the normal operation of the aircraft or an immutable state of affairs’.¹⁰³

A point worth noting is that the trial judge purported to ascertain whether the event was unusual or unexpected from the perspective of the injured passenger.¹⁰⁴ This would suggest invoking a subjective inquiry, which is based on flimsy precedent and threatens to distort the equitable balance of interests sought by MC99. As discussed above, the proper standard should be an objective, holistic inquiry that considers the circumstances of the individual passenger as well as industry norms and standards as part of the overall factual matrix.¹⁰⁵

3. A causal link between the event and the aircraft’s operation?

A curious line of US case law exists that purports to place a gloss on the word ‘accident’. These lower court decisions posit a two-prong test to determine whether an ‘accident’ under Article 17 of WC29/MC99 has occurred: the evidence must demonstrate that: (i) an unexpected or unusual event that was external to the plaintiff occurred (that is, the Saks test) and (ii) this event was a malfunction or abnormality in the aircraft’s operation or a risk characteristic of air travel. Two notable cases illustrate this structurally biased approach.

The first case is Gotz v Delta Air Lines Inc (Gotz).¹⁰⁶ The plaintiff boarded a connecting flight with a heavy carry-on bag and asked a flight attendant to stow it at the front of the aircraft. The attendant refused, citing safety concerns, and directed him to use the overhead compartment in his assigned row. While attempting to place his bag overhead, a nearby passenger suddenly stood up, extending his arm into the plaintiff’s space. To avoid hitting the other passenger, the plaintiff hyper-extended his arm and stepped back, injuring his shoulders. He sued the airline for his injuries. The issue before the District Court was whether the other passenger’s sudden rise constituted an ‘accident’ under Article 17 of WC29 and whether this accident proximately caused the plaintiff’s injury. Applying the Saks formulation, the court required additional evidence of a clear causal connection between the airline’s acts or omissions and the injury-causing event.¹⁰⁷ Concluding that the other passenger’s sudden rise was not an Article 17 ‘accident’, the court clarified that ‘[a]n event cannot fall within the operation of the aircraft if that event is not within the airline’s purview or control’.¹⁰⁸

A similar line of reasoning was adopted in Maxwell v Aer Lingus Ltd (Maxwell).¹⁰⁹ The plaintiff was injured on a flight from Boston to Ireland when another passenger opened the overhead bin, causing a bag of liquor bottles to fall on her head. These bottles did not belong to the plaintiff, and she had not placed them in the bin. The airline typically warned passengers to be cautious when opening overhead bins, issuing this warning twice before departure and again as passengers prepare to disembark. The District Court had to determine if the plaintiff’s injury was a compensable ‘accident’ under WC29. The court applied the ‘unexpected or unusual’ criterion as set forth in Saks and further noted that air carrier liability would be imposed only on those injurious happenings that result from risks that are ‘characteristics of air travel’ in the sense of having some relationship to the operation of the aircraft.¹¹⁰ The court then proceeded to categorize the proper and safe stowage of items in the overhead bins as falling within the defendant’s purview or control, given that flight attendants are typically responsible for securing the bins before take-off.¹¹¹

The cases above are at odds with a parallel line of US case law in which courts squarely rejected putting a gloss on the definition of ‘accident’ that is evidently not contained in Article 17 of WC29/MC99 or Saks. For instance, in Barratt v Trinidad & Tobago (BWIA International) Airways Corporation,¹¹² the plaintiff lined up with other passengers for their scheduled flight. They proceeded through a door leading to a staircase and another door to the tarmac and aircraft. The plaintiff tripped on a piece of protruding metal while descending the stairs and was injured but managed to board the flight with assistance. The plaintiff sought damages for her injuries three years after the incident.

The District Court had to decide whether WC29 applied, which would have barred recovery given the two-year limitation imposed by the treaty (Article 29). The court ruled that WC29 did apply, thus barring the claim. It rejected the plaintiff’s contention that a ‘trip and fall’ occurring within an airport terminal can never come within the Convention’s scope of application because it was not caused by a ‘risk inherent in aviation’.¹¹³ The court affirmed the Saks definition of ‘accident’ and noted that it was ‘in no way limited to those injuries resulting from dangers exclusive to aviation’.¹¹⁴

What emerges from the preceding case law is that there is no controlling authority for lower courts to apply the second prong of the two-part ‘accident’ test endorsed by Gotz and Maxwell (that is, the ‘malfunction or abnormality in the aircraft’s operation’ or the ‘risks peculiar to or characteristic of air travel’ requirement). The issue came before the US Court of Appeals, Second Circuit, but no conclusive answer was provided.¹¹⁵ In Wallace v Korean Air (Wallace),¹¹⁶ the plaintiff was sexually assaulted while on an international flight operated by the defendant airline. Her attacker was a fellow passenger. She sued the defendant to recover for the assault under Article 17 of WC29. The District court dismissed the suit, concluding that the sexual assault was not a ‘risk characteristic of air travel’ and, therefore, was not an ‘accident’ for the purposes of WC29.¹¹⁷

The Second Circuit disagreed with the lower court’s conclusion. The majority acknowledged that, since Saks, two lines of authority had developed. One held that there was a requirement that the accident should have some causal relationship with air travel; the other did not.¹¹⁸ However, the majority did not address the issue of whether imposing an ‘inherent in air travel’ requirement comports with the plain meaning of the Saks formulation. Instead, the majority determined that, even under the narrower interpretation, an ‘accident’ had occurred when a male passenger sexually assaulted a neighbouring female passenger by unzipping and reaching into her pants. The court concluded that the ‘characteristics of air travel increased [the plaintiff’s] vulnerability to [the] assault’ because she was ‘cramped into a confined space beside two men she did not know, one of whom turned out to be a sexual predator’ and was ‘left unsupervised in the dark’.¹¹⁹ The court also alluded to the causal link between the ‘accident’ and the operation of the flight. Even though the victim was sitting in a window seat, the lights were turned down, and there was no indication that the cabin crew was in a position to have seen or anticipated the assault, the court commented that the offender was able to carry out the assault without a single flight attendant noticing a problem.¹²⁰

It is submitted that the requisite causal connection endorsed by the lower courts in Gotz and Maxwell may be refuted on two principal grounds. First, in Wallace, Pooler CJ, concurring with the majority, denounced the gloss placed by lower courts to limit what could constitute an ‘accident’ for failing to recognize that the Supreme Court in Saks had already implicitly rejected such narrow interpretations.¹²¹ It will be recalled that, in Saks, the Supreme Court directed courts to apply its definition of ‘accident’ flexibly and cited approvingly previous lower court decisions that had read Article 17 ‘broadly enough to encompass torts committed by terrorists or fellow passengers’.¹²² Furthermore, in Husain, the Supreme Court reminded courts that the ‘operative language under Saks and the correct Article 17 analysis’ is the determination of whether the injury-causing event or conduct was ‘unexpected and unusual’.¹²³ It is worth mentioning also that, in the English case of Morris v KLM Royal Dutch Airlines,¹²⁴ the Court of Appeal observed that ‘there is nothing in Saks that justifies the requirement that an “accident” must have some relationship with the operation of the aircraft or carriage by air’, and nor does a ‘purposive approach’ to the interpretation of Article 17 require that gloss on the word.¹²⁵ Thus, the requisite causal connection is not derived from mandatory authority.

Second, the purported justification for requiring the injury-causing event to be related to the operation of the aircraft or under the control of the airline is based on modern risk allocation theory. This rationale is clearly evident in the reasoning of the court in Maxwell:

Liability for injuries resulting from [risks characteristic of modern-day air travel] is allocated to the carrier for the simple reason that the carrier is in a far superior position than are passengers to institute protective safeguards…The unexpected event, in other words, while not fully within the carrier’s control, is not wholly beyond the ability of the carrier to influence.¹²⁶

Courts in other signatory States have explicitly rejected such construction of ‘accident’ within the meaning of Article 17, given that the risk allocation line of argument is derived from common law tort theory—a domestic policy consideration—that is, and should be, inapplicable in the context of an international trade law treaty.¹²⁷ Thus, as discussed above, the provisions of MC99 should be construed autonomously to achieve certainty and uniformity.¹²⁸

V. CJEU case law—a black cloud on the horizon

The preceding discussion highlights that the Saks test, notwithstanding its limitations, has been generally accepted as the basic framework for analysing the term ‘accident’ under Article 17 of WC29 and, by extension, Article 17(1) of MC99. No senior court has openly denounced the Saks test or attempted to define the meaning of ‘accident’ anew. The CJEU, however, stands as the sole exception. The emerging case law from the EU signals the breaking of the proverbial dam. However, before the CJEU’s case law is examined and the normative implications considered, it is necessary to understand MC99’s place within the EU legal order.

The former European Community adopted MC99 in its own right pursuant to Article 53(2) of MC99.¹²⁹ MC99 entered into force for all EU Member States and the EU on 28 June 2004, becoming an integral part of the EU legal order. Council Regulation (EC) 2027/97 (as amended by Council Regulation (EC) 889/2002) implements MC99 regarding air carrier liability in the event of aviation accidents.¹³⁰ Notably, Article 3(1) provides that ‘the liability of a Community air carrier in respect of passengers and their baggage shall be governed by all provisions of the Montreal Convention relevant to such liability’. By this route, MC99 became a piece of EU law and, thus, amenable to the CJEU’s competence to interpret its provisions.

1. CJEU’s disruptive interpretation of ‘accident’

The CJEU addressed for the first time the interpretation of the term ‘accident’ within the meaning of Article 17(1) of MC99 in GN v ZU (Niki Luftfahrt),¹³¹ which was a request for a preliminary ruling submitted by the Supreme Court of Austria. The facts of the dispute may be gleaned from the question referred to the CJEU:

Where a cup of hot coffee, which is placed on the tray table of the seat in front of a person in an aircraft in flight, for unknown reasons slides and tips over,¹³² causing a passenger to suffer scalding, does this constitute an ‘accident’ triggering a carrier’s liability within the meaning of Article 17(1) of [MC99]?¹³³

In its brief opinion, the CJEU noted that the ‘ordinary meaning’ given to the concept of ‘accident’ is that of an ‘unforeseen, harmful and involuntary event’, without mentioning the time-honoured Saks test or providing any supporting citation.¹³⁴ The court then concluded that ‘the concept of “accident” within the meaning of [Article 17(1)] covers all situations occurring on board an aircraft in which an object used when serving passengers has caused bodily injury to a passenger, without it being necessary to examine whether those situations stem from a hazard typically associated with aviation.’¹³⁵

Less than three years after its judgment in Niki Luftfahrt, the CJEU delivered another preliminary ruling in JR v Austrian Airlines AG (Austrian Airlines)¹³⁶ concerning the interpretation of the term ‘accident’ under Article 17(1). The facts of the dispute may be gleaned from the question referred to the CJEU:

Is Article 17(1) of [MC99] to be interpreted as meaning that the concept of ‘accident’ within the meaning of that provision covers a situation in which a passenger falls on the last third of a mobile boarding stairway when disembarking from an aircraft—for no ascertainable reason—and sustains an injury, which was not caused by an object used when serving passengers within the meaning of [Niki Luftfahrt], and there was no defect in the quality of the stairway, which, in particular, also was not slippery?¹³⁷

In its reasoning, the CJEU affirmed its novel construction of ‘accident’ as an ‘unforeseen, harmful and involuntary event’ and further emphasized that ‘that concept does not require that the damage is due to the materialisation of a hazard typically associated with aviation or that there be a connection between the “accident” and the operation or movement of the aircraft’.¹³⁸ In the court’s view, that interpretation is consistent with MC99’s objectives of ensuring the ‘protection of consumers in international carriage by air’ by means of a system of strict liability for air carriers while maintaining an ‘equitable balance of interests’ between air carriers and passengers.¹³⁹ The CJEU then concluded by answering the question submitted to it in the affirmative—that is, a passenger’s injurious fall for no ascertainable reason while in the process of disembarking an aircraft qualifies as an ‘accident’ within the meaning of Article 17(1).¹⁴⁰

2. Normative implications—fragmentation of MC99 case law

The CJEU’s rulings in Niki Luftfahrt and Austrian Airlines have not been received favourably by commentators, and rightfully so.¹⁴¹ To begin with, the court’s reasoning in both judgments is methodologically flawed in so far as it merely paid lip service to the tenets of Article 31 of the VCLT. Nowhere in its reasoning does the CJEU examine the ‘ordinary meaning’ of the term ‘accident’ in the context in which it is used, which, as discussed above, calls for a differentiation between cause and effect.¹⁴² Instead, the court relied solely on a teleological approach upon which to base its construction. Furthermore, the opinion delivered in the Austrian Airlines case should dispel any doubts held post-Niki Luftfahrt that the CJEU did not intend to dispose of the ‘externality’ aspect of the causal event.¹⁴³

As the above case law shows, national courts have consistently read an ‘externality’ criterion in the concept of ‘accident’, thereby demonstrating a clear ‘subsequent practice in the application of the treaty which establishes the agreement of the parties regarding its interpretation’ according to Article 31(3)(b) of the VCLT. The requisite ‘externality’ of the injury-causing event acts as a filter against frivolous liability claims and gives the term ‘accident’ reasonable scope that sits easily in the balance struck by MC99. An overlooked virtue of the ‘externality’ criterion is that it also incentivizes air carriers to adopt effective practical measures or design features that would actually improve passenger safety during air travel rather than turn airlines into insurers of their passengers’ health and safety.¹⁴⁴ Thus, the criticism raised against the CJEU is warranted for both undermining the uniformity of the application of MC99 and not providing substantive grounds for doing so.

Another problematic aspect of the CJEU’s non-conformist interpretation of the term ‘accident’ is the prerequisite ‘involuntariness’ of the event, an odd criterion not recognized under the Saks line of authority. Imposing such a curious condition may bar bona fide personal injury claims where a passenger willingly consents to the alleged ‘event’, especially in cases involving onboard medical assistance that is poorly administered, which, in turn, aggravates the passenger’s condition.¹⁴⁵ There is existing authority holding that inadequately administered first aid during a flight resulting in bodily injury may constitute an ‘accident’ for the purposes of Article 17(1).¹⁴⁶

Perhaps the only silver lining in the CJEU’s controversial approach is its rejection of the contention that the concept of ‘accident’ in Article 17(1) should be interpreted as requiring the existence of a hazard typically associated with aviation or a direct connection with the operation or movement of the aircraft. The court correctly observed that such a dubious requirement would not be consistent with either the normal meaning of the concept, the objectives of MC99, or the content of the system of liability established by the Convention.¹⁴⁷

Turning to the long-term implications of the judicial discord, the CJEU’s deliberate decision to break ranks with the ‘common law’ of the Warsaw and Montreal Conventions would destabilize the entire MC99 framework designed to be a uniform liability regime. The court’s pursuit of regional certainty compromises global uniformity underpinning MC99. In the absence of a higher central authority endowed with the power to issue uniform interpretations of MC99 provisions, fragmentation begets uncertainty and unpredictability—precisely what the Convention’s drafters wished to avoid.

As a second prognosis, the CJEU’s rejection of the ‘externality’ criterion practically attributes to air carriers the role of a general-risk insurer of their passengers’ health and safety during the course of the carriage by air, which would heavily thwart the ‘equitable balance of interests’ sought by MC99.¹⁴⁸ Furthermore, the adverse socio-economic consequences following the court’s lopsided pro-consumer approach should not be overlooked. Exposing air carriers to potentially greater liability would result in costly litigation or more costly settlements to avoid litigation, thereby significantly distorting the efficient allocation of resources. Moreover, liability insurance—a significant operational cost for airlines—would likely increase, which may eventually translate into increased ticket prices for passengers.¹⁴⁹ Thus, it is the passengers who, in the long run, would ultimately pay for a regime that purportedly safeguards their interests.

Third, and related to the last point, airlines would be incentivized to surreptitiously engage in passenger profiling and discriminatory pricing in order to share the risk of exposure to liability. MC99 explicitly encourages forum shopping by providing multiple forums for plaintiffs to choose from when bringing an action against a carrier for damages, including the territory of the State Party in which, at the time of the accident, the passenger has his or her principal or permanent residence (Article 33(2)). If the CJEU’s unprincipled, liberal interpretation of the term ‘accident’ were adopted by all 27 EU Member States, airlines may likely resort to increasing airfares for prospective passengers who are either EU citizens or permanent residents to account for the risk of being sued before an EU court in the event of an accident. It is submitted that such discriminatory acts would contravene the principle of equal treatment of passengers implicit in MC99’s commitment to ensuring the protection of the interests of consumers in international carriage by air.

VI. Conclusion

The revival of international air travel in the wake of the receding COVID-19 tide has refocused the spotlight on the inherent hazards of carriage by air. From a legal perspective, the question is whether any of those air travel-related incidents that may result in passenger death or bodily injury are compensable ‘accidents’. In the context of international carriage by air, MC99 provides the sole basis for recovery for injuries (fatal or otherwise) sustained by passengers and precludes actions for personal injury or wrongful death under local law when such claims do not satisfy the conditions precedent to air carrier liability under the Convention.

Article 17(1) of MC99 and its predecessor Article 17 of WC29, the core provisions governing air carrier liability for personal injury and wrongful death claims, have amassed a massive body of case law that has oftentimes proven challenging to navigate. This article sought to determine whether a uniform and coherent set of legal principles could be distilled from the corpus of court decisions to ascertain what constitutes an ‘accident’ within the meaning of Article 17(1). In determining whether a compensable ‘accident’ took place on board the aircraft or during the process of embarking or disembarking, a set of ten principles can be distilled from the extant case law:

• Whether an ‘accident’ has occurred is a question of fact.

• An ‘accident’ is an unexpected or unusual event or happening that is external to the passenger (the Saks test).

• An ‘accident’ that is the cause of an injury is different from the occurrence of that injury itself.

• A passenger’s internal bodily reaction to the aircraft’s regular and expected operation would not be an ‘accident’. It is necessary, therefore, to identify an event or trigger that is physically external to the passenger (that is, the externality criterion).

• The burden resting on the plaintiff is low; he or she need not precisely establish the cause of the injury-causing event nor show that it occurred independently of anything done or omitted by the passenger.

• The external event or trigger must be unexpected or unusual. The characterisation of an event as unexpected or unusual should be answered from the perspective of a disinterested bystander apprised of all relevant circumstances. This holistic, totality-of-the-circumstances approach would take account of the circumstances of the individual passenger as well as industry standards and practices.

• Identifying an ‘event’ requires a flexible application. An ‘event’ may arise from acts, omissions, or a combination of acts and omissions. It is sufficient that some link in the chain of causal events was an unexpected or unusual event external to the passenger.

• If the alleged event is described as inaction or a failure to do something, the absence of action would not amount to an event unless it could be shown to be an omission by reference to some legal standard requiring action.

• However, common law notions of reasonable expectation or failure to act arising from a duty of care owed to passengers are irrelevant to the construction of MC99 in accordance with the principle of autonomy of the Convention’s provisions.

• There is no controlling requirement that there be a causal connection between the injury-causing event and the operations of the aircraft or that it be a risk characteristic of air travel.

It is submitted that the aforementioned principles are the product of courts of signatory States acting collectively through their concordant practice and, therefore, represent a coherent set of rules that should guide future courts to determine whether an alleged event constitutes an Article 17(1) ‘accident’ consistently and predictably. These findings also inform stakeholders in the commercial aviation industry of the delicate balance that MC99 strives to achieve: to ensure the protection of consumer interests in international carriage by air and the need for equitable compensation based on the principle of restitution while, at the same time, maintaining the goal of assuring limited and predictable damages awards for airlines.

Achieving global uniformity is a core aspiration of MC99; however, the emerging case law from continental Europe threatens the stability of the Convention as a uniform code. The CJEU has affirmed its liberal, non-conformist construction of the term ‘accident’ as an ‘unforeseen, harmful and involuntary’ event that need not necessarily be external to the passenger, thus effectively denouncing the long-standing definition set forth by the US Supreme Court in Saks without providing any substantive reasons for doing so. The absence of the ‘externality’ criterion strongly implies that an injury-causing event need not have an ascertainable cause or trigger in order to constitute an Article 17(1) ‘accident’, thereby turning airlines into insurers of their passengers’ health and safety. It was argued that exposing air carriers to greater liability would severely distort the equitable balance of interests sought by the drafters of MC99 and would result in far-reaching socio-economic implications. These adverse consequences include costly litigation or more costly settlements to avoid litigation and higher insurance premiums payable by airlines that would be passed on to consumers in the form of higher-priced tickets.

In sum, should the CJEU hold steadfastly to its lonely furrow deepening the schism between European national courts and their common law counterparts, it may be high time for the international aviation community to convene and discuss the prospect of adopting a protocol to conclusively clarify the proper interpretation of the term ‘accident’ within Article 17(1) and restore global uniformity.

My thanks go to the anonymous referee for their helpful comments on earlier versions of this article.

Footnotes