International Aviation Law and Passenger Protection: Liability for Delay, Cancellation and Denied Boarding under the Montreal Convention
Flying across borders means your rights as a passenger no longer rest on a single country’s consumer law alone. When a flight is delayed, cancelled, or you’re bumped off an overbooked plane, the first question a lawyer asks is: does the Montreal Convention apply, and if so, what does it actually promise you? This article breaks down the treaty’s framework for delay, cancellation, and denied boarding, and where it stops short — leaving room for regional rules like EU261 or national aviation regulations to fill the gap.
What Is the Montreal Convention
The Montreal Convention of 1999 (MC99), formally the Convention for the Unification of Certain Rules for International Carriage by Air, is the modern treaty governing airline liability on international flights. It replaced the older, more airline-friendly Warsaw Convention system and today binds well over 130 countries, including the United States, the EU member states, the UK, Canada, India, and most major aviation markets.
Where it applies, MC99 is not optional; it overrides inconsistent national law and is usually the exclusive basis for a passenger’s claim against the carrier for the matters it covers.
When Does It Apply
The Convention applies to international carriage, meaning the agreed place of departure and the agreed place of destination are in two different states that are both parties to the Convention (or, in some cases, a round trip with a stop in another Convention state). Purely domestic flights fall outside MC99 and are governed instead by domestic aviation and consumer law.
Liability for Delay
Article 19 makes the carrier liable for damage caused by delay in the carriage of passengers, baggage, or cargo — unless it proves that it and its agents took all measures that could reasonably be required to avoid the damage, or that it was impossible to take such measures.
Importantly, this is not a flat, automatic payout. A passenger must prove an actual, quantifiable loss flowing from the delay — a missed connecting booking, a hotel stay, meals, or other reasonable expenses incurred because of the delay. Compensation for pure inconvenience or distress is generally not recoverable under this article.
The Delay Liability Cap
Article 22(1) caps a carrier’s liability for delay-related damage at 6,303 Special Drawing Rights (SDR) per passenger, following the revision that took effect on 28 December 2024 (up from 5,346 SDR under the 2019 figures). SDRs are an IMF-defined unit whose value against any given currency fluctuates daily, so the cap should be converted at the prevailing rate when a claim is filed.
This cap can be pierced only in narrow circumstances — for instance, where the damage results from an act or omission done with intent to cause damage, or recklessly and with knowledge that damage would probably result.
Liability for Cancellation
MC99 does not contain a standalone article titled “cancellation.” In practice, a cancelled flight is analysed either as a delay (if the passenger is rebooked and eventually carried, just later than planned) or as a straightforward breach of the contract of carriage, for which ordinary contract remedies — such as a refund of the fare — apply outside the Convention’s damage-liability framework.
This is a key nuance: the Montreal Convention regulates compensation for the consequential damage flowing from disruption, not the underlying obligation to refund an unused ticket. Passengers seeking a fare refund for a cancelled flight typically rely on the airline’s contract of carriage, consumer protection law, or regional regulation, rather than MC99 itself.
Denied Boarding: A Gap the Convention Leaves Open
Denied boarding — being bumped from a flight, usually because of overbooking — sits awkwardly under MC99. The Convention has no dedicated provision creating a right to fixed compensation for denied boarding, unlike delay or baggage, which have their own articles and caps.
Where a bumped passenger is eventually carried on a later flight, courts and practitioners often analyse the resulting loss under the same delay principles as Article 19, subject to the Article 22(1) cap and the requirement to prove actual damage. But the more generous, fixed-sum compensation regimes many travellers are familiar with — such as the EU’s Regulation 261/2004, UK261, or equivalent national rules in other jurisdictions — exist entirely outside the Montreal Convention. They apply in parallel, and where they’re available, they typically offer a simpler, no-fault path to compensation than proving actual loss under MC99.
For practitioners, the practical takeaway is to check both regimes: MC99 for the treaty-based liability framework, and any applicable regional passenger-rights regulation for fixed compensation that may apply on top of it.
Death, Injury, and Baggage: The Wider Liability Picture
Though this article focuses on delay, cancellation, and denied boarding, the Convention’s broader liability structure is worth knowing:
All of these figures reflect the 2024 revision (effective 28 December 2024), which raised the previous 2019 limits by roughly 18 to 20 percent to account for inflation, as required by the Convention’s built-in five-year review mechanism under Article 24.
How to Pursue a Claim
Step 1: Confirm the Convention Applies
Check that both the origin and destination states (and any agreed stopping place) are parties to MC99, and that the flight segment in question is genuinely international rather than domestic.
Step 2: Document the Loss
Because delay and baggage claims require proof of actual damage, keep boarding passes, rebooking confirmations, hotel and meal receipts, and any written communication from the airline about the disruption.
Step 3: Notify the Carrier in Writing
For baggage claims in particular, MC99 imposes strict notice deadlines — typically within 7 days for damaged baggage and 21 days for delayed baggage, counted from the date the baggage was placed at the passenger’s disposal. Missing these windows can bar an otherwise valid claim.
Step 4: Check Regional Compensation Rules in Parallel
Before assuming MC99 is your only option, check whether a regional passenger-rights regulation (such as EU261 or a national equivalent) also applies to your flight — these often provide fixed compensation without requiring proof of individual financial loss.
Step 5: File Within the Limitation Period
Article 35 sets a strict two-year limitation period for bringing an action, running from the date of arrival, the date the aircraft ought to have arrived, or the date carriage stopped. Unlike many domestic limitation rules, this period is generally treated as one that extinguishes the right itself, not merely a procedural bar, so it is rarely capable of being extended.
Frequently Asked Questions
No. It only makes the carrier liable for delay if the passenger proves an actual, quantifiable loss, and even then only up to the 6,303 SDR cap. A delay that causes no provable financial loss does not generate a claim under this article.
The two regimes cover different things and can apply together. EU261 provides fixed compensation for the disruption itself (delay, cancellation, or denied boarding), while MC99 governs proven consequential damages and has its own caps. Airlines and courts generally avoid double recovery for the same loss, but the availability of one regime does not automatically exclude the other.
Not directly. MC99 has no dedicated denied-boarding article. Any resulting claim is usually pursued either through the general delay framework under Article 19 (if you were eventually carried) or through separate regional passenger-rights rules, which typically offer a more straightforward compensation route.
A Special Drawing Right is an international reserve unit maintained by the IMF, based on a basket of major currencies. Using SDRs lets the Convention’s caps hold roughly consistent real value across currencies and over time, rather than being fixed in one currency that could be eroded by inflation or exchange-rate shifts.
Article 24 requires ICAO to review the limits every five years for inflation. The most recent revision took effect on 28 December 2024, raising the 2019 figures by approximately 18 to 20 percent.
Article 35 sets a two-year limitation period from the date of arrival (or the date the aircraft should have arrived, or the date carriage stopped). This period is treated strictly and is generally not extendable.
No. It applies only where the agreed departure and destination points are in two different Convention states (or involve an agreed stop in another Convention state). Purely domestic itineraries are governed by domestic law instead.
Disclaimer: This article is for general informational purposes and does not constitute legal advice. Liability limits are expressed in SDRs and their currency equivalents change daily; readers should verify current figures and consult a qualified aviation law practitioner before relying on this information for an actual claim.
