Edited by Jürgen Basedow, Giesela Rühl, Franco Ferrari and Pedro de Miguel Asensio
I. Rules on contractual liability
1. The Warsaw Convention system
Liability for the vast majority of all international carriage by air of persons, baggage and cargo was for over 70 years subject to the Convention for the Unification of Certain Rules Relating to International Carriage by Air. One of two versions was applied, either the original version signed at Warsaw on 12 October 1929 (Convention of 12 October 1929 for the unification of certain rules relating to international carriage by air, 137 LNTS 11), or, as in most cases, the Warsaw Convention in the version of the Hague Protocol of 1955 (Protocol of 28 September 1955 to amend the Convention for the unification of certain rules relating to international carriage by air, 478 UNTS 371). These two versions of the Convention were amended among others by the Guadalajara Supplementary Convention (Convention of 18 September 1961, supplementary to the Warsaw Convention, for the unification of certain rules relating to international carriage by air performed by a person other than the contracting carrier, 500 UNTS 31) as well as by the Montreal Protocols of 1975 (Montreal Additional Protocol No 1 (Additional Protocol No 1 of p. 4025 September 1975 to amend the Convention for the unification of certain rules relating to international carriage by air signed at Warsaw on 12 October 1929, 2097 UNTS 23); Montreal Additional Protocol No 2 (Additional Protocol No 2 of 25 September 1975 to amend the Convention for the unification of certain rules relating to international carriage by air signed at Warsaw on 12 October 1929 as amended by the Protocol done at The Hague on 28 September 1955, 2097 UNTS 64); Montreal Additional Protocol No 3 (Additional Protocol No 3 of 25 September 1975 to amend the Convention for the unification of certain rules relating to international carriage by air signed at Warsaw on 12 October 1929 as amended by the protocols done at The Hague on 28 September 1955 and at Guatemala City on 8 March 1971, Doc 9147); Montreal Additional Protocol No 4 (Montreal Protocol No 4 of 25 September 1975 to amend the Convention for the unification of certain rules relating to international carriage by air signed at Warsaw on 12 October 1929 as amended by the Protocol done at The Hague on 28 September 1955, 2145 UNTS 31)).
During the era of its prevalence, this so-called ‘Warsaw Convention system’ was the basic international private law regime for civil aviation, covering several areas. This system governs the following issues among others: the conclusion of contracts relating to carriage of passengers, the legal aspects of carriage of baggage and cargo, the peculiarities of combined carriage, the enforcement of the law and questions relating to tort and contract liability. The central characteristic of the Warsaw liability system is the privilege of the air carrier to limit its liability, particularly relating to personal injuries.
As a consequence of the permanent evolution and changes to which international air traffic is exposed, the need for numerous modifications of the convention system proved inevitable. These modifications led to an extreme fragmentation and complexity of the existing Warsaw regime, rendering it eventually incapable of meeting the high demands of such an international and significant complex of conventions.
In addition, this liability system (including the limitation of liability) was questioned by the aircraft industry itself, as air carriers complied voluntarily, by accession to the Intercarrier Agreement of Passenger Liability (available at <www.iata.org>), with a nearly unlimited liability. Ultimately, these various factors created the impetus for a general revision of the liability system.
The Warsaw liability system has recently been supplanted by the Montreal Convention (Convention of 28 May 1999 for the unification of certain rules relating to international carriage by air, 2242 UNTS 309). However, despite the advanced ratification status of this new liability regime, it does not yet apply worldwide. Accordingly, for certain international air connections, the Warsaw Convention and its Protocols and supplementary Conventions are still effective.
2. The Montreal Convention
Prompted by various ambiguities resulting from the mentioned modifications and the fragmented regime of the Warsaw Convention, the international community of states adopted a new convention at the conference of the International Civil Aviation Organization (→ICAO) in Montreal on 28 May 1999 (the Montreal Convention). This new Convention aims at unifying and modernizing the numerous rules relating to the liability resulting from air carriage contracts. The Montreal Convention for the Unification of Certain Rules for International Carriage by Air entered into force between the ratifying states on 4 November 2003, following ratification by the →USA as 30th state. Thereupon, →Germany ratified the Convention on 29 April 2004, and on 28 June 2004 the Convention entered into force in all EU Member States as well as in the European Union itself (→European Union and private international law). As of the end of 2015 there are 119 parties to the Convention.
The Montreal Convention will gradually replace the Warsaw Convention, but is not intended to abrogate it. Thus, art 55 of the Montreal Convention states that it prevails over all the instruments of the Warsaw Convention. Moreover, there is no particular obligation to abrogate the Warsaw Convention and its subsequent Conventions. The provisions of the Warsaw regime will therefore continue to play a role, albeit a subordinate one. Before the Montreal Convention is ratified by the entire community of nations, further issues will arise, particularly that of the (parallel) applicability of the two regimes.
a) Scope of application
The Montreal Convention applies to all international carriage of persons, baggage or cargo performed by aircraft for reward. It is applicable on the one hand to circumstances taking place on a flight between two State Parties. On the other hand, the Convention can also be applied to transports which begin and end within the territory of a single State Party with a stopping place within the territory of a third state, irrespective of whether the third state is a State Party.
The Convention is not applicable to one-way flights to non-Parties and to return flights from non-Parties to State Parties.
b) p. 41Rules on liability
The Montreal Convention regulates several liability scenarios, most importantly including the liability for passengers, baggage, cargo and delay.
Air carrier liability results out of an accident on board the aircraft or in the course of any embarking or disembarking operations. For such liability, the accident must lead to death or bodily injury of a passenger. Basically, every unexpected or special incident without any active involvement of the passenger is defined as an accident. In such a case, the air carrier is liable for the damage resulting thereby to an in principle unlimited amount, subject to possible contributory negligence or other wrongful act or omission of the injured person. If the air carrier is able to prove such negligence, it will be fully or partly relieved from potential liability. If not, its liability is based on a two-tier system, with distinct liability principles essentially based on the amount of damage. The first tier is applied for damage not exceeding 113,100 SDRs per passenger (one SDR = Special Drawing Right corresponding to about EUR 1.27 as of January 2016), whereby the carrier is not able to exclude or limit its liability (strict liability). The second tier embodies a liability for amounts of damages exceeding 113,100 SDRs. Here, liability is unlimited, ie the air carrier is liable for all damage provided that it is due to its (even minor) negligence or other wrongful act or omission.
The air carrier can only be exempt from liability if it establishes a lack of fault on its part. No other limitation of liability is provided for. Claims for punitive →damages are expressly excluded. To fulfil the immediate financial needs of the injured or their descendants, the air carrier can be obliged to make an advance payment required by the carrier’s national law, as is the case in the EU and Switzerland. However, such advance payments in no way constitute acknowledgement of liability and may be offset against any amounts subsequently paid as damages by the carrier.
Liability for baggage may result from its destruction, loss or damage, if the causing event took place either on board the aircraft or in the course of any embarking or disembarking operations. Liability for unchecked baggage, including personal items, arises only if the damage was caused by the fault of the carrier or its servants or agents. The carrier is not liable if and to the extent that the damage resulted from the inherent defect, quality or vice of the baggage.
Whereas the Warsaw Convention is based on a liability system with a weight related restriction, the Montreal Convention restricts the liability, independently of the weight of the baggage, to 1,131 SDRs. This limit applies per passenger for registered and for non-registered baggage. Higher limits may be agreed upon if the passenger has made a special declaration of interest in delivery at destination at the time when the checked baggage was handed over to the carrier. The upper limit of liability does not apply to cases of acts or omissions of the carrier, its servants and agents, done with intent to cause damage or recklessly and with knowledge that damage would probably result.
The air carrier is liable for the destruction or loss of or the damage to the cargo, if the damage cannot be attributed to an inherent defect or quality of the cargo, or to a defective packing, and if the incident causing the damage occurred while the air carrier was in charge of the cargo. Additionally, the fact that losses are caused by an act of war or an armed conflict leads to an exemption from liability. The liability may in any event not exceed 19 SDRs per kilogram, unless the consignor has made a special declaration of interest in delivery at destination at the time when the package was handed over to the carrier.
This limit is unbreakable, even in cases of recklessness or intent (eg theft by the air carrier and its servants and agents), an aspect which is remarkable and has been criticized.
The carrier is also liable for damage occasioned by delay in the carriage of passengers, baggage or cargo, if the air carrier or its servants or agents failed to take all measures that could reasonably be required to avoid the damage. This liability for damage caused by delay is in principle limited to the total amount of 4,694 SDRs (passenger), 1,131 SDRs (baggage) and 19 SDRs per kilogram (cargo). The first two limits of liability (passengers and baggage) apply only where the damage did not result from an act or omission of the carrier, its servants and agents, done with intent to cause damage or recklessly and with knowledge that damage would probably result.
c) p. 42Further issues of regulation
As with the Warsaw Convention, the Montreal Convention allows a choice of the traditional jurisdictions in which actions for damages can be brought within the territory of a State Party. Thus actions are permissible before the court (i) of the air carrier’s domicile or its principal place of business (→Domicile, habitual residence and establishment), (ii) of the carrier’s place of business at which the contract was made, or (iii) at the place of destination of the carriage.
In addition to these traditional jurisdictions, the Montreal Convention additionally allows that actions for damages resulting from the death or injury of a passenger may be brought before a court in the territory of a State Party in which the passenger has their principal and permanent residence at the time of the accident. Furthermore, it has to be a court in the territory of a State Party to or from which the carrier operates services and in which the carrier conducts its business from premises leased or owned by the carrier itself.
(2) Court fees
The mentioned limitations of liability do not prevent the court from awarding additional court costs and other expenses of the litigation incurred by the plaintiff, including interest. Here, the regulations of the competent court apply. The additional amount will, however, only be granted if the amount of the damages awarded, excluding court costs and other expenses of the litigation, exceeds the sum which the carrier offered in writing to the plaintiff within a period of six months from the date of the occurrence causing the damage, or before commencement of the action, if that is later. Here, the Montreal Convention encroaches upon the national rules of procedure, which may, as is well known, provide very different rules in this regard.
(3) Arbitration proceedings
A prior agreement to settle potential liability disputes by arbitration is possible only for the carriage of goods and is thus excluded for passenger claims. However, a subsequent agreement to settle passenger claims by arbitration is acceptable. In this respect the Convention states that the arbitration tribunal has to apply the provisions of the Convention.
(4) Transport documents
The Warsaw liability system requires that the carrier makes express reference to the limitation of liability in order to be able to invoke such limitation later. The Montreal Convention has considerably eased and simplified this rule. Although certain statements are still required, no sanctions are connected with their omission. Furthermore, electronic tickets are explicitly included in the Montreal Convention. Electronic air waybills are allowed and the Montreal Convention includes certain rules on their tenor. Equally, the omission of information does not lead to the elimination of the liability limits.
d) European law aspects
Following the entry into force of the Montreal Convention, the European Council enacted the Regulation (EC) No 2027/97 of 9 October 1997 on air carrier liability in the event of accidents,  OJ L 285/1. The Regulation was amended by 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,  OJ L 140/2. According to this Regulation, the Montreal Convention is applicable to all air carriage by EU airlines, regardless of whether a national or an international carriage is concerned. In addition, detailed duties to supply references and information are imposed in the case of carriage within EU boundaries, and the Regulation provides for insurance protection to cover the expenses incurred in compensation cases. The contracting states have the duty to ensure that their air carriers maintain adequate insurance coverage. On request of other Member States, evidence of such insurance must be provided. In the European Union, Regulation (EC) No 785/2004 of the European Parliament and of the Council of 21 April 2004 on insurance requirements for air carriers and aircraft operators,  OJ L 138/1, amended by Commission Regulation (EU) 285/2010 of 6 April 2010 (amending Regulation (EC) No 785/2004 of the European Parliament and of the Council on insurance requirements for air carriers and aircraft operators,  OJ L 87/19) lays down minimum amounts for the insurance coverage for airlines and aircraft operators. As an example, coverage is provided for at 250,000 SDRs in case of personal injury or death of a passenger, 1,131 SDRs for baggage and 19 SDRs per kilogram for cargo. Because the European p. 43Union is a party to the Montreal Convention, national courts of the EU Member States have the option to turn to the →Court of Justice of the European Union (CJEU). Through the preliminary ruling procedure provided for in art 267 TFEU (The Treaty on the Functioning of the European Union (consolidated version),  OJ C 326/47), the CJEU is competent to decide on questions of interpretation of the Montreal Convention. The CJEU has repeatedly identified the Montreal Convention as an integral element of the legal system of the Community and has addressed its proper interpretation (eg ECJ Case C-344/04 The Queen, on the application of International Air Transport Association and European Low Fares Airline Association v Department for Transport  ECR I-403).
e) Final remarks
The entry into force of the Montreal Convention clarifies the regime of the international air traffic. Through its terms, the numerous international law treaties and protocols as well as the regulations under European law have been consolidated into one single instrument. Against this background, it is no coincidence that to a considerable extent the Montreal Convention comprises elements of pre-existing conventions. Some terms were to a greater or lesser degree adopted from the original Warsaw Convention or the Hague Protocol. Some other provisions are taken from the Guatemala City Protocol (Protocol of 8 March 1971 to amend the Convention for the unification of certain rules relating to international carriage by air signed at Warsaw on 12 October 1929 as amended by the protocol done at The Hague on 28 September 1955, Guatemala City Protocol (1971), Doc 8932, available at <www.forwarderlaw.com> and <www.jus.uio.no>), from the Montreal Protocols and from the Intercarrier Agreement, which was implemented by the aircraft industry. The strength of the Convention undoubtedly lies in the amalgamation of all these provisions into one single convention, at last providing legal certainty and legal clarity to all parties involved in an air carrier contract.
The fact that, in spite of the often diverging interests found in the international community and the sometimes difficult negotiations during the ICAO conference, 52 states signed the newly created convention at the end of the conference is a reflection of the great international preparedness to leave the old Warsaw regimes to the past and to replace them with the new Convention. As an impressive number of states have joined the new Convention, this hope has proven justified.
II. Rules on third-party liability2
A variety of legal relationships exist among parties involved in air transportation. Regarding the transportation of persons and goods by air, international conventions have led to an extensive unification of the law of contract. However, third parties can also be affected by air transportation. The issue of tortious liability in air transport arises generally in cases of aircraft accident or where, in the operation of the aircraft, third parties suffer damage. A non-contractual claim for damages can be pursued against one or several liable parties. In the field of air transportation, liability for third-party damages is generally incumbent on the aircraft operator. In addition to third-party liability, depending on the specific circumstances of the case, contractual claims may also arise.
1. Liability of the aircraft operator
a) International rules
The initial efforts to standardize liability for damage caused by a foreign aircraft to third parties on the surface began in the early 1930s. These endeavours resulted in the Rome Convention 1933 (Convention of 29 May 1933 for the unification of certain rules relating to damage caused by aircraft to third parties on the surface, (1937) 8 JAL 312), which was supplemented with additional insurance regulations by the Brussels Protocol of 1938, signed on 29 September 1938 (Protocol Supplementary to the Convention for the Unification of Certain Rules Relating to Damage Caused by Aircraft to Third Parties on the Surface, signed in Rome on 29 May 1933, done at Brussels on 29 September 1938, ICAO Doc 107-CD (CD-ROM format) (Stephen Latchford and Samuel E Gates, ‘International Regulation’ (1939) 10 JAL(C) 277, 281ff)). Since these two Conventions were ratified by only a small number of states, a revision followed the p. 44Second World War via the →ICAO and on 7 October 1952 a new Rome Convention was signed (Convention of 7 October 1952 on damage caused by foreign aircraft to third parties on the surface, 310 UNTS 181). The Rome Convention 1933 is superseded by the new Rome Convention 1952 between contracting states which have ratified both Conventions (art 29 Rome Convention 1952). The revision of the Rome Convention 1952 was undertaken by ICAO in the mid-1970s and led to the signing of the 1978 Montreal Protocol to the Rome Convention 1952 on 23 September 1978 (Protocol of 23 September 1978 to amend the Convention on damage caused by foreign aircraft to third parties on the surface, ICAO Doc No 9257).
In addition to unifying certain substantive and procedural legal issues, the Conventions aimed at providing adequate compensation for third-party damage on the surface. Through the establishment of limitations on liability, however, they were intended to do so without hindering the development of international aviation. In particular, the idea that the aviation industry should be protected as a young sector of the economy is also to be found in the Warsaw Convention, which for the first time harmonized the contractual liability of the air carrier.
While the Rome Conventions on liability of 1933 and 1952 are based upon the same principles, the Rome Convention 1952 is more precise and detailed on many points. The Montreal Protocol 1978 mainly establishes higher liability limits.
The Rome Conventions of both 1933 and 1952 are in principle applicable where an aircraft that is registered in a contracting state causes damage in and to the territory of (to the surface of) another contracting state (art 23 Rome Convention 1952; art 20(1) Rome Convention 1933). The scope of application was adapted in the 1978 Montreal Protocol to the Rome Convention 1952 and, in particular, was extended to include cases where, even though the aircraft itself is not registered in a contracting state, the aircraft operator’s principal place of business or permanent residence is in another contracting state (art XII of the 1978 Montreal Protocol to the Rome Convention 1952). Thus, even if the USA ratified the Convention, the incidents of 11 September 2001 would not have fallen within its scope of application because all the aircraft involved were registered in the USA all damages were caused on American territory.
Liability in the case of an aircraft collision is only rudimentarily regulated by the Rome Conventions. They only stipulate that the aircraft operators are either jointly and severally liable to third parties suffering damages (art 6 Rome Convention 1933), or that each aircraft concerned shall be considered to have caused the damage such that the operator of each aircraft shall be liable (art 7 Rome Convention 1952). However, the Convention does not apply to claims brought by the aircraft owner, the crew, the passengers or shippers of goods carried on board of one aircraft against the operator of the other aircraft involved (or vice versa) since such damages will not have occurred on the surface (art 24 Rome Convention 1952). Accordingly, the applicable national law determines the non-contractual liability between the parties involved. A unification of the law pertaining to aircraft collision liability was attempted but not pursued by the →ICAO.
The liable party in general is the aircraft operator (art 2 Rome Convention 1952; art 4 Rome Convention 1933). The operator and the registered or commercial owner of the aircraft are, particularly given today’s typical financing models, often not identical.
The aircraft operator is subject to strict liability (art 2 Rome Convention 1933; art 1(1) Rome Convention 1952). It is liable provided that the damage is proven and attributable to an aircraft in flight. Thus, the takeoff and landing process is covered by the Convention while the so-called taxiing, ie the movement of aircraft on the ground at the airport, is not. In cases of contributory or sole negligence on the part of the damaged party, the liability of the operator is to be set aside or reduced accordingly (art 6(1) Rome Convention 1952; art 3 Rome Convention 1933).
The aircraft operator’s liability is limited per incident to a fixed amount determined by the weight of the aircraft. Originally, the limits of liability were expressed in Poincaré francs (art 11 Rome Convention 1952; art 8 Rome Convention 1933). In the 1978 Montreal Protocol to the Rome Convention 1952, the limits were raised and set in SDR of the International Monetary Fund. One Special Drawing Right is approximately EUR 1.27 (as of January 2016). The limits of liability range between 300,000 SDRs for an aircraft weighing 2,000 kg or less and 2.5 million SDRs for an aircraft weighing more than 30,000 kg, with 65 SDRs to be added to the 2.5 million SDRs p. 45for each additional kilogram above 30,000 kg. The liability with respect to loss of life or personal injury may not exceed 125,000 SDRs per killed or injured person (art III 1978 Montreal Protocol to the Rome Convention 1952).
Particularly with regard to small aircraft, the limits of liability are disproportionate to the damage potentially inflicted by the aircraft. For instance, when a Rockwell Commander 112 TC, a small aircraft with a flight weight of about 1,300 kg, crashed into the Pirelli skyscraper in Milan in April 2002, it caused personal and property damage in excess of EUR 50 million with more than 150 injured and three dead (including the pilot). If, as in this case, the total loss exceeds the limits of liability, then the distributable sum should be allocated preferentially to cover personal injury damages over property damages (art 8(3) Rome Convention 1933; art 14(b) Rome Convention 1952; art IV 1978 Montreal Protocol to the Rome Convention 1952). The Rome Convention 1933 states, for example, that only one-third of the total distributable sum is to be allocated for the reparation of property damages and the remaining two-thirds for personal damages. If claims exclusively relate to either personal or property damages, such claims shall be reduced in proportion to their respective amounts (art 14(a) Rome Convention 1952 and art IV 1978 Montreal Protocol to the Rome Convention 1952; art 9 Rome Convention 1933), taking into account the liability limits for personal injuries.
There are only a few instances in which the liability limits do not apply (art 12 Rome Convention 1952; art 14 Rome Convention 1933). For example, gross negligence, reminiscent of the approach adopted by the Warsaw Convention and its Hague Protocol of 1955, leads to the unlimited liability of the aircraft operator. Other grounds for unlimited liability include failing to possess adequate insurance coverage and the wrongful taking and making use of an aircraft without the consent of the person entitled to use it (art 12(2) Rome Convention 1952; art 14(b) Rome Convention 1933).
Claims must be notified within a period of six months from the date of the incident that gave rise to the cause of action (art 10 Rome Convention 1933; art 19 Rome Convention 1952). Additionally, the absolute statute of limitations of three years as well as the relative statute of limitations both need to be observed. The latter was extended from the original one year to two years in the Rome Convention 1952 (art 17(1) Rome Convention 1933; art 21(1) Rome Convention 1952).
In the Rome Convention 1952, jurisdiction is allocated only to the place where the damage occurred (art 20(1) Rome Convention 1952). In the earlier Convention, the plaintiff could still choose between the place where the damage occurred and the defendant’s ordinary place of residence (art 16 Rome Convention 1933).
The introduction of compulsory insurance in the Rome Convention 1933 was a new concept for that era (art 12 Rome Convention 1933). In addition, the Brussels Protocol of 1938 restricted the defences available to the liability insurer, which remained unaltered in subsequent instruments. From today’s perspective, compulsory insurance for aircraft owners and operators is common. At the European level, compulsory insurance is provided for air carriers and aircraft operators in Regulation (EC) No 785/2004 as amended by Commission Regulation (EU) 285/2010 of 6 April 2010. In addition, in many countries and in the EU the issuance of an operating licence is contingent upon proof of adequate insurance. Finally, the Montreal Convention of 1999 demands that the contracting states require their air carriers to maintain adequate coverage (see I.2.d) above).
b) National rules
The Rome Conventions of 1933 and 1952, as well as the Protocols of 1938 and 1978, were ratified by only few states and are therefore only of marginal practical importance. Consequently, despite unification efforts, the respective applicable national law is not only decisive in domestic conflicts but also in many cross-border cases.
Many countries have developed bodies of legislation dealing with air transportation that regulate liability for surface damages. The corresponding liability systems, as well as their scopes of application, vary considerably. The applicable law to liability for surface damage has to be determined in accordance with the applicable national rules on private international law.
c) The modernization process
Since the Rome Conventions and the Protocols were not successful and the acceptance by the community of states was low, the ICAO began to address modernization of the Rome Convention 1952 in 2000. The events of 11 September 2001 gave this project a new impetus, p. 46with special attention being paid to the risk of terrorism.
The →ICAO’s efforts resulted in two draft conventions, which on the one hand lay down rules on the liability for acts of terrorism and unlawful interference (the Unlawful Interference Convention (Convention of 2 May 2009 on compensation for damage to third parties, resulting from acts of unlawful interference involving aircraft, ICAO Doc 9907-LC/193, Attachment D, and ICAO Doc No 9920)), and on the other hand regulate the liability for situations without unlawful interference (the General Risk Convention (Convention of 2 May 2009 on compensation for damage caused by aircraft to third parties, ICAO Doc 9907-LC/193, Attachment E, and ICAO Doc No 9919)).
In principle, the Unlawful Interference Convention provides for the strict liability of aircraft operators. It is no longer a requirement, as was the case in the Rome Conventions, that damage be caused by a foreign aircraft, but rather that the damage must be caused by an aircraft on an international flight. Also under these premises, the incidents of 11 September 2001 would fall outside the scope of application because all four flights were domestic rather than international flights (for the same result under the Rome Conventions but for different reasons, see II.1.a) above).
Liability of the aircraft operator is determined by the weight of the aircraft and is limited to a maximum of 700 million SDR for an aircraft weighing more than 500,000 kg. Since this instrument is intended to regulate the compensation of incidents of the magnitude of 11 September 2001, the limited liability of the aircraft operator has been amended with a supplementary compensation mechanism. For the additional compensation level, an organization must be established which is financed through contributions of the aircraft operators. A similar two-tiered compensation system and channelling of liability is foreseen in maritime law, under the 1969 CLC (International Convention on Civil Liability for Oil Pollution Damage of 29 November 1969, 973 UNTS 3) and Fund Convention (International Convention on the Establishment of an International Fund for Compensation for Oil Pollution Damage of 18 December 1971, ceased to be in force 24 May 2002, 1110 UNTS 57; as replaced by the Protocol to the International Fund for Compensation for Oil Pollution Damage of 27 November 1992, 1956 UNTS 255; the Protocol of 27 September 2000; and the Protocol of 16 May 2003,  OJ L 78/24) (→Liability, limitation of maritime).
The predominant criticism of the Unlawful Interference Convention is that aircraft operators are financially responsible for the →damages caused by terrorists, even though they are also victims of the same terrorist acts. Critics argue that in such cases the affected states and governments should be responsible for the compensation of damage.
Like the Unlawful Interference Convention, the General Risk Convention requires an international flight and is applicable if there is no unlawful interference, as defined in the Unlawful Interference Convention. The two-tiered liability system of the General Risk Convention echoes the Montreal Convention, in that the aircraft operator is liable up to the maximum liability limit, unless (contributory) negligence of the injured party applies. Furthermore, the aircraft operator can only avail itself of the limitation of liability if it can prove that the damage was caused neither by its own negligence nor by that of its servants or agents, or that it can be solely attributed to a third party. In contrast to the Unlawful Interference Convention, no supplementary compensation mechanism is provided for in the General Risk Convention.
During the Diplomatic Conference held in Montreal between 20 April and 2 May 2009, the final versions of the two Conventions were adopted and opened for signature. The General Risk Convention will enter into force on the 60th day following the ratification by the 35th state; the Unlawful Interference Convention will enter into force on the 180th day following the ratification by the 55th state, provided that these states together achieve a certain passenger volume. As of the end of 2015, the General Risk Convention has been signed by 13 states, five acceded the Convention. The Unlawful Interference Convention has been signed by 11 states, four states acceded to it.
2. Additional liable parties
Depending on the circumstances of the case, further parties apart from the aircraft operator might be subject to liability. Prime examples here arise in product liability cases and in relation to acts and omissions by the providers of air traffic control.
a) p. 47Product liability
In air transportation product liability, ie the manufacturer’s responsibility for a deficient product, has become increasingly important, and is also reflected in the corresponding number of court cases. Defective design, construction or manufacturing can all be the cause of damage. In the EU, a certain level of harmonization was achieved via the Products Liability Directive (Council Directive 85/374/EEC of 25 July 1985 on the approximation of the laws, regulations and administrative provisions of the Member States concerning liability for defective products,  OJ L210/29), requiring the imposition of strict liability. There is no harmonization on the international level. In a number of states, however, product liability is regulated separately. Eligibility to lodge a claim based on product liability is not limited to third parties on the ground but also extends to, among others, the aircraft owner, the passenger and the crew.
b) Liability for air traffic control
Air transport depends heavily on air traffic control. If the latter functions poorly or not at all, it can be the cause of accidents and damage. While air traffic control is generally perceived as a public service, nowadays it is also open to privatization. According to art 28 of the Convention of 7 December 1944 on International Civil Aviation (Chicago Convention, 15 UNTS 295), the contracting states are in principle responsible for the provision of air traffic control services. In light of this understanding, it becomes clear that the liability for acts or omissions of air traffic controllers is often subject to the rules on general state liability.
Potential liability is assessed based on the applicable national law, since no unification of law has yet been achieved in this area, despite ICAO efforts in this regard. The discussion concerning the unification of the law has been given new impetus thanks to the EU initiative regarding establishing a Single European Sky (SES). As in the case of a functional airspace block or in instances where foreign-located air traffic controllers carry out air traffic control duties, such activities reach both within and outside state borders. Although the issue of the delegation of air traffic control duties between states in near-border regions is not new (eg as concerning the aircraft collision above Überlingen, Germany in summer 2002), the EU initiative has lent the topic a new dimension. In this context, complex questions regarding the applicable (state) liability rules arise, pertaining not only to private persons, but also relating to recourse between the affected states.
Ruwantissa Abeyratne, ‘The ICAO Conventions on Liability for Third-Party Damage Caused by Aircraft’ (2009) 34 Air and Space Law 403;
Karl-Heinz Böckstiegel, ‘A Historic Turn in International Air Law: The New IATA Intercarrier Agreement on Passengers Liability Waives Liability Limits’ (1996) 45 ZLW 18;
Michael Chatzipanagiotis, ‘Liability Aspects of Air Traffic Services Provision’ (2007) XXXII Annals of Air and Space Law 326;
Paul S Dempsey and Michael Milde, International Air Carrier Liability: The Montreal Convention of 1999 (McGill Institute of Air and Space Law 2005);
Isabella Henrietta Philepina Diederiks-Verschoor, Pablo MJ Mendes de Leon and M Butler, An Introduction to Air Law (9th edn, Kluwer Law International 2012);
Elmar Giemulla and Ronald Schmid, Frankfurter Kommentar zum Luftverkehrsrecht, vol 3 (Luchterhand loose leaf, supplement of 22 January 2015);
Stephan Hobe and Otto Kimminich, Einführung in das Völkerrecht (9th edn, UTB 2008);
Michael Milde, ‘Liability for Damage Caused by Aircraft on the Surface’ (2008) 57 Zeitschrift für Luft- und Weltraumrecht 532;
Michael Milde, International Air Law and ICAO (2nd edn, eleven 2012);
Martin Ryff, ‘Das Montrealer Übereinkommen’ (1/2000) 128 ASDA SVLR Bulletin 8;
Roland Schmid and Wolf Müller-Rostin, ‘Die Änderungen des internationalen Lufttransportrechts durch das Montrealer Übereinkommen von 1999’ (2/2003) 135 ASDA SVLR Bulletin 13;
Francis Schubert, ‘Warsaw Claims and ATC Liability’ (1997) XXII-I Annals of Air and Space Law 237;
Francis Schubert, ‘The Liability of Air Navigation Services in the Single European Sky’ (2003) XXVIII Annals of Air and Space Law 57;
Walter Schwenk and Elmar Giemulla, Handbuch des Luftverkehrsrechts (4th edn, Heymann 2013);
Christopher M Shawcross, Peter Martin and Kenneth MacDonald Beaumont, Shawcross & Beaumont Air Law, vols 1–2 (Butterworth, loose leaf, last supplement of 12 June 2015);
George N Tompkins, Liability Rules Applicable to International Air Transportation as Developed by the Courts in the United States: From Warsaw 1929 to Montreal 1999 (Kluwer Law International 2010).
This entry section is a revised and updated version of the entry ‘Air Transportation (Contractual Liability)’ by Alexander von Ziegler, published in Jürgen Basedow and others (eds), The Max Planck Encyclopedia of European Private Law, vol 1 (OUP 2012) 38 et seq.
This entry is a revised and updated version of ‘Air Transportation (Third-Party Liability)’ by Giovanna Montanaro, published in Jürgen Basedow and others (eds), The Max Planck Encyclopedia of European Private Law, vol 1 (OUP 2012) 42 et seq.