Naji Alabed

The contours of liability for international airline accidents lack clarity due to inconsistency among the circuits in applying the “unusual or unexpected” inquiry established by the Supreme Court decades ago. If adopted by other circuits, a decision in the First Circuit from 2022 would have significant ramifications for the industry.  

With the rise of international commercial aviation, there also came a concern that the prospect of liability stemming from airplane accidents would stifle investment in the new industry.[1] Accordingly, an international effort to address this risk culminated in the Warsaw Convention of 1929, which, among other things, established a standard liability ceiling for accidents that occur during the course of international air travel.[2] The Warsaw Convention was largely viewed as “airline-friendly,” as the drafters intended it to be.[3]  

However, the Warsaw Convention regime unduly constrained  passenger protections over the following decades. In particular, the 125,000 franc ceiling codified in the agreement[4]—the equivalent of $8,300 in 1933[5]—was viewed as inadequate in light of inflation and the rising standard of living during the middle to late twentieth-century.[6] Additionally, the existence of affordable liability insurance and the lower than feared levels of actual accidents magnified the disproportionate protection of the airlines.[7] Asynchronous efforts to remedy the deficiencies in the Warsaw Convention regime in the decades following World War II resulted in a patchwork of new instruments which supplemented the Warsaw Convention but lacked uniform participation.[8]

In this context, the Supreme Court decided Air France v. Saks in 1985.[9] Although the Warsaw Convention provided that airlines would only be liable provided that the injuries to passengers resulted from an “accident,”[10] the treaty did not define “accident.” The Supreme Court held that “accident” means “an unexpected or unusual event or happening that is external to the passenger.”[11] Providing additional color to the “accident” inquiry, the Supreme Court held that the “definition should be flexibly applied,” noting with approval that “accident” had been found by lower courts to encompass intentional torts committed by other passengers.[12] Furthermore, the Court held that only one link in the chain of causation leading to the injury needs to fit the aforementioned definition of “accident” to establish airline liability.[13] Although the Court ultimately found that a normal change of pressurization which occurs in a cabin upon ascent and descent, the event which caused the injury is Saks, was not “unusual or unexpected,” the Court established a liberal standard for the lower courts to follow in applying the “accident” inquiry.

The Supreme Court chimed in once again on the scope of “accident” in Olympic Airways v. Husain in 2004.[14] The Court held that a “rejection of an explicit request for assistance” is encompassed by the definition of “accident” it formerly delineated in Saks.[15] In dissent, Justice Scalia disapprovingly characterized this holding as providing that “inaction, or a refusal to act” could be an “accident.”[16] Husain significantly expanded the scope of events which could be found to be “accidents,” encompassing failures to act by airlines when such failures are “unusual or unexpected.”

Shortly before Husain was decided, the U.S. ratified the Montreal Convention, the successor of the Warsaw Convention, in 2004.[17] The principle impetus of the Montreal Convention was to reunify the disaggregated system of international air travel liability first established by the Warsaw Convention.[18] In so doing, the Montreal Convention established itself as more passenger-friendly than its predecessor, recognizing in its preamble “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.”[19] Among other things, the Montreal Convention established a two-tier system of liability. Under the first tier, airlines are strictly liable for up to 100,000 Special Drawing Rights (SDR).[20] For any amount exceeding 100,000 SDR, a passenger must prove negligence by the airline.[21]

Although the Supreme Court has yet to revisit its definition of “accident” since the Montreal Convention, the First Circuit added more depth to the scope of “accident” in Moore v. British Airways, PLC in 2022.[22] There,  the Court highlighted that an “accident” is an event or happening that is unusual or unexpected, noting that, although there is overlap between the definitions of unusual or unexpected, they are not the same and only one needs to be satisfied in order to establish liability.[23] More significantly, it found that whether an event or happening is unexpected should be determined from the perspective of “an ordinary, reasonable passenger in the plaintiff’s position.” This assertion is not explicitly supplied by the Supreme Court’s jurisprudence on the topic, but is bolstered by the Supreme Court’s instruction to apply the definition of “accident” flexibly in Saks.[24]

Moore’s framing of the “unusual or unexpected” inquiry stands in contrast to that of the Fifth Circuit in Blansett v. Continental Airlines, Inc., which was decided the same year as Husain.[25] In Blansett, the Court found that an airline’s failure to provide warning to a passenger of the risk of developing deep vein thrombosis during long international flights was not an “unusual or unexpected.”[26] This was so despite an assumption that an industry standard had developed to supply such warnings.[27] Unlike Moore, Blansett did not approach the analysis from the perspective of an ordinary reasonable passenger. Rather, it found that since “many” airlines did not supply such warnings—despite an industry standard to do so—and since the FAA does not require such warnings, a failure to supply such warnings cannot be found to be “unusual or unexpected.”[28] Accordingly, Blansett determined that the “unexpected” inquiry should be determined from the perspective of the airline industry according to what is “‘normal and routine’ across the industry.”[29]

The potential ramifications to the airline industry should Moore’s standard be adopted by the other circuits include increased compliance costs and exposure to liability. Airlines would no longer be able to assert that deficiencies in their protocols, procedures, or airplane and equipment designs cannot be found to be “unexpected” simply because the same are “normal or routine” across the industry, as occurred in Blansett, if an ordinary reasonable passenger would find the conditions to be unexpected.


[1] Naneen K. Baden, The Japanese Initiative on the Warsaw Convention, 61 J. Air L. & Com. 437, 438 (1995).

[2] Id. at 439.

[3] Howard Sokol, Final Boarding Call-The Warsaw Convention's Exclusivity and Preemption of State Law Claims in International Air Travel: El Al Israel Airlines, Ltd. v. Tseng, 74 St. John's L. Rev. 227, 251 (2000).

[4] Convention for the Unification of Certain Rules Relating to International Transportation by Air art. 20, Oct. 12, 1929, 49 Stat. 3000 (“Warsaw Convention”).

[5] Andreas F. Lowenfeld & Allan I. Mendelsohn, The United States and the Warsaw Convention, 80 Harv. L. Rev. 497, 499  n.10 (1967).

[6] Baden, supra note 1, at 441; Bin Cheng, A New Era in the Law of International Carriage by Air: From Warsaw (1929) to Montreal (1999), 53 Int'l & Comp. L.Q. 833, 835 (2004).

[7] Bade, supra note 1, at 442.

[8] Id. at 440.

[9] France v. Saks, 470 U.S. 392 (1985).

[10] Warsaw Convention, supra note 4, at art. 17.

[11] France v. Saks, 470 U.S. 392, 405 (1985).

[12] Id.

[13] Id.

[14] Olympic Airways v. Husain, 540 U.S. 644 (2004).

[15] Id. at 654–55.

[16] Olympic Airways v. Husain, 540 U.S. 644, 657 (2004)(Scalia, J., dissenting).

[17] Convention for the Unification of Certain Rules for International Carriage by Air Done at Montreal on 28 May 1999, ICAO, (last visited Nov. 27, 2022).

[18] [18] Jennifer McKay, The Refinement of the Warsaw System: Why the 1999 Montreal Convention Represents the Best Hope for Uniformity, 34 Case W. Res. J. INT'l L. 73, 84 (2002); Thomas J. Whalen, The New Warsaw Convention: The Montreal Convention, 25 Air & Space L. 12, 12 (2000).

[19] Convention for the Unification of Certain Rules for International Carriage by Air art. 17, 28 May 1999, ICAO Doc. 9740 Preamble (hereinafter Montreal Convention).

[20] Id. at art. 21; SDR is an asset created by the International Monetary Fund the value of which is linked to the US Dollar, Euro, Chinese Yuan, British Pound, and Japanese Yen. See Special Drawing Rights, International Monetary Fund, (last visited Mar. 30, 2023).

[21] Id.

[22] Moore v. Brit. Airways PLC, 32 F.4th 110 (1st Cir. 2022).

[23] Id. at 115–16.

[24] Id. at 117–18; France v. Saks, 470 U.S. 392, 405 (1985).

[25] Blansett v. Cont'l Airlines, Inc., 379 F.3d 177 (5th Cir. 2004).

[26] Id. at 182.

[27] Id.

[28] Id.

[29] Blansett did not explicitly frame its inquiry in this way, but Moore characterized such an approach as conducting the “accident” inquiry from the perspective of the airline industry according to what is “’normal and routine’ across the industry.” See Moore v. Brit. Airways PLC, 32 F.4th 110, 117 (1st Cir. 2022).