Abstract

The Montreal Convention of 1999 was adopted to harmonise the liability regime governing international air carriage, replacing the fragmented framework created by earlier instruments such as the Warsaw Convention 1929, the Hague Protocol 1955 and the Chicago Convention 1944. By introducing uniform rules on airline responsibility for passenger injury or death, the Convention aimed to provide predictability for carriers while enhancing protection for passengers. This paper examines the historical development of international air law and situates the Convention within both public and private international law. It then analyses the ways in which selected jurisdictions, including the United States, Canada, the United Kingdom, Germany, the Netherlands and Italy, incorporate the Convention into their domestic legal frameworks. 

The discussion shifts to the substantive provisions of Articles 17 and 29, which restrict claims to narrowly define categories of loss, as demonstrated by judicial debates over the definitions of “accident” and “passenger”. Particular emphasis is placed on Article 33, which outlines the Convention’s five jurisdictional gateways. The fifth jurisdiction, aimed at expanding access to justice by allowing claims in the claimant’s country of residence, has instead created considerable uncertainty due to its reliance on the vague concept of “commercial agreements” between carriers, as evidenced in Akulinina v iFly.

The paper concludes that although the Convention has succeeded in establishing a universal framework for airline liability, ambiguities in interpretation remain, particularly regarding the fifth jurisdiction, which continue to hinder its effectiveness in balancing passenger rights with carrier protections.

Introduction

The Montreal Convention (“the Convention”) regulates the liability of airlines for losses, injuries and fatalities during international travel. It seeks to establish a consistent and uniform legal framework for resolving claims brought by passengers against air carriers. This paper will achieve three objectives. First, it will explain the history of international air law and how the Convention enforces a uniform set of rules for international air carrier liability; however, its domestic legal status can differ depending on the jurisdiction, as some are directly effective, while others require national legislation in a dualist system for applicability. Second, it will analyse how the Convention allows passengers to make claims if the airline is liable for passenger injury, death, baggage damage and delays, while safeguarding the airline by outlining specific restrictions and limits on the amount of compensation permitted. Finally, and most importantly, it will highlight the particular jurisdictions outlined within the Convention.

These are outlined in Article 33, which clarifies the jurisdictional validity of claims against airlines. The Convention addresses claims that arise from the potential injury or death of a passenger. Although the five jurisdictions are recognised internationally, the fifth jurisdiction is one of the Convention’s most complex and debated provisions. The fifth jurisdiction aims to improve access to justice for passengers. However, it involves several issues related to legal uncertainty or unequal compensation for passengers. This paper will clarify the circumstances in which passengers can make claims against airlines under Article 33 of the Convention, as well as evaluate the challenges in applying the fifth jurisdiction.

International Law and the Convention

There is a key challenge that carriers operating across borders must face, namely, the traditional uncertainty that affects any cross-border industry. Recognising these complexities, the international community has aimed to standardise air accident litigation through several treaties, which form part of international law. The concept of international law itself is not without difficulties. Unlike the relationship between the state and its citizens, international law lacks the coercive power to enforce rules and exert control.

International law is not without ambiguity. For example, customary international law is an unwritten but binding source of international law, consisting of two elements: general state practice, which involves the consistent actions or statements by states in their conduct, rules and diplomacy, and opinio juris, the belief that such practice is followed because of a legal obligation (ICJ Statute and Nicaragua v USA). These two components must align, enabling rules and treaties to exist and operate. Courts often consider both practice and opinio juris in their rulings. State practices generally need to be consistent and widespread over time for a rule to develop. Customary law can exist independently of treaties or alongside them. It can also evolve as state behaviour and legal convictions change over time (Treves, 2006). This process shows that customary international law evolves from consistent state behaviour combined with a sense of legal obligation and is recognised as a binding source of international law. 

The Convention promotes mutual respect by establishing a single, uniform set of rules for international air travel, an industry that depends on cross-border cooperation. Since aviation connects nearly every country, states have an interest in consistent liability standards that safeguard passengers while providing airlines with clear obligations. By standardising these rules, the Convention prevents conflicts between national laws, guarantees fair treatment of travellers and facilitates the smooth operation of global aviation, making it highly regarded and effective.

Private international law, also known as conflict of laws, consists of rules that govern legal disputes involving different jurisdictions. It determines which country’s courts have jurisdiction, which legal system should be applied and how foreign judgements are recognised and enforced. While national laws are the main sources of private international law, its scope can differ among countries. 

HISTORY OF AIR LAW

Aviation law developed as aeroplanes became more common in the 20th century, and countries needed regulations to keep flying safe and organised. The Paris Convention 1919 was the first major agreement. It gave each country complete control over the airspace above its territory and set early standards for pilot licenses and aircraft registration. This was significant because it laid the foundation for international aviation law. Another important milestone was the Chicago Convention 1944, which established the International Civil Aviation Organisation. This organisation, part of the United Nations, set global safety standards and facilitated cooperation among countries on aviation issues. The Chicago Convention also reaffirmed that each country retained control over its own airspace. 

As commercial aviation expanded, new issues emerged, particularly concerning passenger safety and airline liability. The Warsaw Convention 1929 established international rules for airline liability, holding airlines responsible for injuries to passengers or loss of baggage, although the compensation limits were relatively low. Later, the Hague Protocol 1955 increased those limits, providing greater protection to travellers. By the late 20th century, the system had become outdated, leading to the Convention. It modernised liability rules by introducing a two-tier system: airlines are automatically responsible for damages up to a certain amount, and for larger claims, they must prove they were not at fault. It also recognised electronic tickets and enhanced passengers’ rights.

In summary, aviation law has evolved gradually through these conventions. From the Paris Convention’s emphasis on sovereignty to the Warsaw and Hague agreements on liability to the Chicago Convention’s promotion of global cooperation, and finally the modernisation of the Convention, these treaties established the foundation of aviation law we still rely on today.

DOMESTIC APPLICATION

The Convention provides international protection, but when travelling within a country, passengers do not have the same rights. Countries can choose to incorporate the Convention into their domestic law. The following paragraphs will explain how different countries adopt the Convention into domestic law, using the United States, Canada, the United Kingdom, Germany, the Netherlands and Italy as examples. 

The United States has incorporated the Convention into domestic law through implementing legislation and judicial recognition. The US ratified the Convention in 2003, thereby enforcing this binding law under US international law. Congress subsequently applied the Convention’s regulations in US courts, specifically allowing passengers to pursue claims concerning airline liability in domestic federal courts. The US has adopted the specific definitions of terms and concepts used in the Convention, such as “accident” and “damage”, when reviewing cases related to international flights. The Convention pre-empts conflicts and discrepancies in state laws regarding airline liability for international flights by establishing consistent passenger rights across jurisdictions. 

In Canada, the Convention is incorporated through the Carriage by Air Act 2002, which enacts the Convention as part of Canadian law, attaching the full text at the end of the statute. This method allows the Convention to be applied directly in Canadian courts without the need to rewrite its provisions in a different language. One key area covered is bodily injury to passengers, where the Convention sets out a framework of liability for injuries or death occurring during international carriage by air. Canada has extended these liability rules to domestic flights, ensuring passengers are protected under a consistent standard whether travelling within the country or abroad (Dempsey, 2008). By adopting the Convention in this manner, the law enforces the Convention’s limits on compensation, ensuring that claims are managed in accordance with its original provisions. Incorporating the Convention through the Carriage by Air Act illustrates how Canada incorporates international aviation agreements into domestic law while preserving the Convention’s intended legal framework.

In the United Kingdom, the Convention is implemented through the statutory framework of the Carriage by Air Acts 1961 and 1962. This legislation authorises the government to enact international air carriage treaties via subordinate legislation. Under this authority, the Convention was incorporated into domestic law by the Carriage by Air Acts (Implementation of the Montreal Convention 1999) Order 2002 (SI 2002/263). This is a form of secondary legislation that annexes the text of the Convention in its Schedule. It has a direct impact on UK law.

Under the European Union’s regulatory regime, the Convention was complemented by EC 889/2002. This amended EC 2027/97 to harmonise the liability regime for air carriers across all Member States and to ensure consistency with the Convention framework. Following the United Kingdom’s withdrawal from the European Union, EU law no longer applied directly to the United Kingdom. However, under the European Union (Withdrawal) Act 2018, retained EU law preserved the effect of Regulation 889/2002 in domestic legislation. Consequently, the substantive rules of the Convention continue to govern.

In Germany, the Convention is implemented through the European Union framework, which grants it direct effect in German law without needing to incorporate its provisions into national legislation. The Convention sets out the rules for airline liability in international carriage, including passenger injury or death, baggage loss or damage and flight delays, with specific compensation limits. While it regulates claims for proven damages, Germany also applies EU Regulation 261/2004 alongside it, offering standardised compensation and assistance in cases of cancellation, delay or denied boarding. This dual system ensures that passengers travelling to or from Germany are protected under both the Convention’s international liability regime and the additional rights provided by European law.

The Netherlands adopted a constitutional approach where the Convention automatically takes effect without requiring separate legislative measures. Under Dutch constitutional principles, international treaties of a generally binding nature become part of Dutch domestic law immediately upon ratification. The Convention entered into force in the Netherlands in 2004 and has also been integrated into the Dutch Civil Code. Although there is limited national case law regarding the Convention’s application, Dutch courts interpret its provisions consistent with the Convention’s terms, including the jurisdictional rules in the fifth jurisdiction. The Dutch legal system offers a supportive environment for incorporating the Convention, reinforced by general principles of treaty law and codified civil obligations.

In Italy, the Convention has been incorporated into domestic law mainly through its enforcement by national courts and its alignment with broader European Union regulations. Italy’s Law No. 12 of 10 January 2004 is the specific national legislation that ratified the implementation of the Convention into Italian law. This law authorised Italy’s ratification of the Convention and established the direct applicability of the Convention’s provisions within the domestic legal system. This ensured that its rules on air carrier liability and passenger rights are enforceable by Italian courts.

Italian courts recognise the Convention as a legal instrument that takes precedence over general EU regulations for matters concerning international carriage by air. The Italian Supreme Court has affirmed the Convention’s jurisdictional rules, including those related to Article 33, which governs where claims can be brought, reflecting the interaction with Italian procedural law. This judicial approach is complemented by Italian private international law provisions, which recognise the Convention’s rules for jurisdiction and competence. The fifth jurisdiction option is respected, allowing claimants to bring a claim in their principal and permanent residence if the airline operates services there. This provides a vital method for passengers or their heirs to bring claims conveniently in Italy under the Convention.

Basis of Claims

When filing a claim under the Convention, it is crucial to understand what the Convention covers and its limitations. Two articles specifically define the scope of the Convention. Article 17 addresses the death and injury of passengers. This article states, “the carrier is liable for damage sustained in the case of death or bodily injury of a passenger”. This applies only if “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”. 

Article 29 relates to the basis of claims. The article states, “in the carriage of passengers, baggage and cargo, any action for damages, however founded, whether under this Convention or in contract or in tort or otherwise, can only be brought subject to the conditions and such limits of liability as are set out in this Convention without prejudice to the question as to who are the persons”. This article clarifies that any claims from any person must adhere to the limits of liability established within the convention. Its significance is clear through the understanding that damage claims can only concern the carriage of “the carriage of passengers’ baggage and cargo”. 

It is important to note that claims outside the scope of the convention cannot be pursued. The case of Stott v Thomas Cook exemplifies this. Mr Stott, a wheelchair user, suffered serious failures by Thomas Cook Tour Operators in accommodating his disability during boarding and throughout the flight. He attempted to claim damages under the UK Disability Regulations for humiliation and distress, but the court ruled that the Convention barred such claims. Since his injuries were not bodily injuries as required by Article 17, and Article 29 limits additional causes of action outside the Convention, his claim was unsuccessful. While the Convention imposes strict liability on airlines for specific passenger injuries, this case illustrates how airlines benefit, as the restriction of claims prevents passengers from pursuing legal action for damages that fall beyond the Convention’s limits.

Several conceptual difficulties emerge in pinpointing the exact types of claims that may fall within the scope of the convention. Specifically, determining what constitutes an “accident” or who qualifies as a “passenger”. The following cases illustrate different examples of confusion from previous cases and highlight the lack of clear definitions for the terms “accident” and “passenger”.

First, the concept of the term “accident” was addressed in Luftfahrt. This incident occurred when a passenger’s daughter was travelling with him on board a Niki Luftfahrt aircraft. After the beverage service had finished and while the plane was in motion, the hot coffee that the father had ordered, which was resting on his tray table, spilt all over his daughter, who was seated beside him. The man decided to sue Niki Luftfahrt under Article 17 of the Convention. The airline argued “no ‘sudden and unexplained event’ had led to the cup of coffee being tipped over”, meaning it could not fall under Article 17 since it was not an accident. The courts found that the literal meaning of an accident must be “first, is ‘sudden’ or ‘unusual’ and, second, has an origin ‘external’ to the person of the passenger concerned”. 

Second, this was later clarified by JR v Austrian Airlines, which states, “the concept of ‘accident’, in its ordinary meaning and in the context of which it forms part, is that of an unforeseen, harmful and involuntary event and 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”. In this case, JR fell unexpectedly while disembarking from the aircraft. This was deemed an accident under the Convention.

It is a matter of debate whether the courts have taken the correct approach in defining an accident. Many scholars believe that the Convention is unclear in cases such as those presented. In the Luftfahrt case, it can be argued that the courts did not act properly because the cup could have been removed when signs of turbulence appeared. This incident was sudden, unusual, unforeseen, harmful and involuntary. 

Third, the term “passenger” has encountered some judicial review. In Herd v Clyde Helicopters, a police sergeant’s family sued Clyde Helicopters Ltd over the death of Sergeant Herd, who operated surveillance equipment in the helicopter. The accident involved only the pilot’s actions, yet Herd’s role was operational, as he contributed to the flight but did not control it. Herd was regarded as a passenger despite his involvement in guiding the pilot. The case raises the issue of whether someone performing duties onboard should be classified as a crew member rather than a passenger, which influences the liability and legality of such claims. 

Finally, Disley v Levine illustrates how the Herd v Clyde Helicopters case is applied in the opposite way. Ms Disley was taking a flying lesson when an accident occurred. Unlike Herd, the court decided she was not a passenger for the following reasons. First, Disley was on the aircraft for the purpose of flight training, not for carriage. Additionally, it was argued that Disley played an essential role in flying the aircraft, and without her, the aircraft could not have been operated, which meant she was regarded as part of the crew in this case. Lastly, her contract was for instruction, not carriage. It is well established that a member of the aircraft crew is not considered a passenger; instead, they are subject to domestic labour laws. 

The basis of claims is complex when assessing whether passengers or carriers benefit more. As shown in the cases, the Convention’s lack of a clear definition and its use of the term “passenger” without providing a proper explanation leave courts to interpret the meaning when situations arise. This creates difficulties for plaintiffs trying to bring a claim under the Convention. Although passengers have considerable freedom to choose the jurisdiction in which they wish to bring a claim, they are still limited by the conditions and provisions of the Convention. Therefore, based on the case evaluations, it can be concluded that carriers are generally favoured under the Convention. However, this is problematic because it disadvantages claimants and ultimately fails to meet its intended purpose. 

Jurisdictional Gateways

Article 33 of the Convention outlines five jurisdictional gateways through which a claim can be filed. Notably, only the passenger or claimant has the right to choose the jurisdiction where the claim is made. The defendant carrier is limited to contesting the legitimacy of that jurisdiction by arguing that a jurisdictional gateway has not been satisfied. 

The five jurisdictional gateways are as follows: first, the carrier’s domicile; second, the place of principal business; third, the place of business through which the contract was made; fourth, the court of the place of the destination; and finally, the fifth jurisdiction states that parties can file a claim in the “… territory of one of the States Parties.” The fifth jurisdiction has raised issues in the courts due to differing interpretations by countries. Some treat the fifth jurisdiction as considering the claimant’s permanent residence, while others dismiss this approach. This section will discuss the fifth jurisdiction and its significance in achieving a clearer understanding of it.

Article 33 explicitly states that“an action for damages must be brought, at the option of the plaintiff, in the territory of one of the States Parties”. This phrase clearly limits where claims can be initiated. Actions should be filed in jurisdictions connected to the carrier, such as its domicile, main place of business or destination. The gateways do not include interline agreements or marketing arrangements as sufficient to establish jurisdiction, as the provision aims to ensure that only courts closely linked to the airline’s legal or operational presence can hear such cases.

AKULININA V IFLY

To assess the application of the Convention, particularly the fifth jurisdiction, we can examine the case of Akulinina v iFly. Paragraph 46 of Akulinina clearly elaborates on the jurisdictional bases by introducing the fifth jurisdiction for claims arising from the death or injury of a passenger. This addition was included to improve passenger protection by permitting claims to be made in the courts of the passenger’s principal and permanent residence, provided the airline operates, directly or through a commercial partnership, and maintains a business presence in that country. This way, the Convention seeks to prevent claimants from being compelled to litigate in unfamiliar forums, thus supporting access to justice for passengers and their families.

The Akulinina case stems from a fatal helicopter crash on 20 August 2019. The crash resulted in the deaths of two passengers and the pilot. The claimants, dependents of one of the deceased passengers, brought the case to the England and Wales High Court. The claim asserted that the Court had jurisdiction under Article 33 of the Convention. The issue in this case focuses on whether the court has jurisdiction under Article 33 of the Convention, based on the defendant carrier’s provision of services to or from the UK in accordance with a commercial agreement and its conduct of business from premises in the UK. Since the helicopter flight was not international, it is also necessary to assess whether the flight would be considered international, given that the helicopter was owned and operated by iFly. As it is a company based in Greece, the agency was the same from London to Athens. These issues centre on whether the commercial agreement is valid when referencing the Convention.

The Court, however, found that it lacked jurisdiction under Article 33 of the Convention, as the plaintiffs did not provide sufficient evidence to demonstrate that the Defendant was operating services to and from the UK on another aircraft in accordance with a commercial agreement.

The case allows us to explore the extent of the fifth jurisdiction. The scope issue at 24 concerns the requirement that services must either be provided by the “air carrier’s own aircraft” or by “another aircraft operating under a commercial agreement”. For Article 33 to apply, the air carrier must have some presence in the relevant jurisdiction, whether through premises leased or owned by itself or by another carrier with which it has a commercial agreement. The scope is also limited in that Article 33 would not apply simply because an interline deal or a marketing arrangement exists between air carriers. Instead, there must be both a direct connection by the airline itself or another carrier and the existence of a commercial agreement to establish the necessary link. 

The Akulinina case highlights the complexity of defining a commercial agreement under the fifth jurisdiction, as it can make such claims unsuitable for litigation. The court’s dismissal reflected the difficulties claimants face in providing credible evidence of the necessary operational commercial ties beyond superficial arrangements. This demonstrates the challenges in applying the fifth jurisdiction framework, where vague definitions create obstacles to establishing jurisdiction and can lead to potentially unnecessary legal disputes.

The definition of a commercial agreement within the context of the fifth jurisdiction remains complex and imprecise. While the provision requires more than interline agreements or marketing arrangements, it does not clearly specify the scope of cooperation or operational relations necessary between carriers. This ambiguity results in diverse judicial interpretations and imposes a burden on claimants to demonstrate substantive business ties. Consequently, despite the Convention’s and the fifth jurisdiction’s aim to expand access to justice, uncertainty remains in the practical application of the fifth jurisdiction, making each case dependent on the specific details of the commercial relationship involved.

Conclusion

The Montreal Convention was established to govern the liability of airlines during international travel, but it has sparked controversy over balancing passenger protection and carrier interests. Articles 17 and 29 show this tension: while passengers can seek compensation for injury or death, claims are strictly limited to the categories outlined in the Convention, excluding damages like humiliation or distress. The judicial interpretation of key terms such as “accident” and “passenger” remains uncertain, as courts have debated who qualifies under these definitions. Cases such as Luftfahrt and JR v Austrian Airlines highlight the ambiguity surrounding the term “accident.” Meanwhile, Herd v Clyde Helicopters and Disley v Levine underline the difficulties in determining who qualifies as a passenger.

Article 33, especially the fifth jurisdiction, has also caused tension due to jurisdictional disputes. The Convention aimed to allow passengers to sue in their home forum, but it has strict requirements. These include the airline maintaining a commercial agreement or a physical presence in that country. For instance, in Akulinina v iFly, the court found that the airline’s failure to meet these conditions formally meant the fifth jurisdiction did not apply. These requirements protect airlines from litigation in commercially unrelated jurisdictions, but they also make it more difficult for passengers to access justice.

Although the Convention achieves its goal of establishing a universal framework for international aviation liability, its vagueness in defining key terms and the fifth jurisdiction means that it does not consistently balance passenger rights with airline protections. Further judicial interpretation or legislative clarification is needed to ensure the uniform and fair application of the Convention, especially regarding the fifth jurisdiction.

INTERNATIONAL CONVENTIONS

Convention for the Unification of Certain Rules for International Carriage by Air (adopted 28 May 1999, entered into force 4 November 2003), 2242 UNTS 309 (Montreal Convention).

Convention for the Unification of Certain Rules Relating to International Carriage by Air (adopted 12 October 1929, entered into force 13 February 1933), 137 LNTS 11 (Warsaw Convention).

Convention Relating to the Regulation of Aerial Navigation (Paris, 13 October 1919), 11 LNTS 173 (entered into force 11 July 1922).

Protocol to Amend the Convention for the Unification of Certain Rules Relating to International Carriage by Air, signed at Warsaw on 12 October 1929 (adopted 28 September 1955, entered into force 1 August 1963), 478 UNTS 371 (Hague Protocol).

Statute of the International Court of Justice (adopted and opened for signature 26 June 1945), 33 UNTS 993.

INTERNATIONAL CASE LAW

Corfu Channel (United Kingdom of Great Britain and Northern Ireland v. Albania), 1949.

Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) [1984] ICJ Rep 392.

NATIONAL LAW

Akulinina & Anor v iFly SA [2022] EWHC 166.

C-532/18 GN v ZU (Judgement of the Court, Fourth Chamber, 19 December 2019), ECLI:EU: C:2019:1127.

Carriage by Air Act 1961; Carriage by Air (Supplementary Provisions) Act 1962.

Carriage by Air Acts (Implementation of the Montreal Convention 1999) Order 2002 (SI 2002/263).

Case C-589/20 JR v Austrian Airlines AG (Judgement of the Court, Third Chamber, 2 June 2022) ECLI:EU: C:2022:419.

Disley v Levine (t/a Airtrak Levine Paragliding) [2002] 1 WLR 785 (CA).

European Union (Withdrawal) Act 2018.

Herd v Clyde Helicopters Ltd [1997] UKHL 6.

In re Air Crash of Long Island, New York, on July 17, 1996, 30 F Supp 2d 631 (SDNY 1998).

In re Mexico City Aircrash of 31 October 1979 (1983) 17 Avi. 18,387.

Re Deep Vein Thrombosis and Air Travel Group Litigation [2006] 1 AC 495.

Regulation (EC) No 889/2002 of the European Parliament and of the Council of 13 May 2002 amending Council Regulation (EC) No 2027/97 on air carrier liability in the event of accidents, 2002, OJ L140/2.

Stott v Thomas Cook Tour Operators Limited [2014] AC 1347.

BOOKS AND JOURNALS

Baker R. (2010). Customary International Law in the 21st Century: Old Challenges and New Debates.

Dempsey, P. (2008). Accidents & Injuries in Air Law: The Clash of the Titans. (McGill University Institute of Air and Space Law) <https://www.mcgill.ca/files/iasl/Titans.pdf> Accessed 24 August 2025.

International Law Commission (2018). Identification of Customary International Law.

Treves, T. (2006). ‘Customary International Law’ in Max Planck Encyclopaedia of Public International Law.