The Reasonable Measures Test: The Second Half of the Defense Airlines Almost Never Complete
When an airline invokes extraordinary circumstances to reject a compensation claim, they are relying on only half of what the regulation actually requires. The full defense is a two-part test, and airlines routinely satisfy only the first part. Understanding the second part is one of the most reliably effective ways to challenge an extraordinary circumstances rejection.
The defense airlines almost never complete
When a passenger receives a rejection citing extraordinary circumstances, the typical letter follows a predictable pattern. It identifies an event: weather, ATC restrictions, technical fault, security incident, strike. It references Article 5(3) of EU261. It concludes that compensation is therefore not owed.
This letter is legally incomplete. It addresses only the first half of what the regulation actually requires. The second half, which the airline has the burden to prove, is almost never included in initial rejections. Its absence is not a technicality. It is often the reason the defense fails when tested.
Article 5(3) of EU261 does not simply say that airlines are excused from compensation when extraordinary circumstances occur. It says that airlines are excused when extraordinary circumstances occur and when the disruption could not have been avoided even if all reasonable measures had been taken. Both conditions have to be satisfied. Neither one alone is sufficient.
Airlines almost always satisfy the first condition and ignore the second. Passengers who accept the rejection at face value never realize that the airline has only made half the argument. Passengers who understand what the regulation actually requires can force the airline to complete the defense, and in a substantial share of cases, the airline cannot.
What the regulation actually says
The text of Article 5(3) reads: "An operating air carrier shall not be obliged to pay compensation in accordance with Article 7, if it can prove that the cancellation is caused by extraordinary circumstances which could not have been avoided even if all reasonable measures had been taken."
Three things are worth noting about this language.
First, the burden of proof is on the airline. The phrase "if it can prove" places the entire evidentiary burden on the carrier, not on the passenger. The airline has to establish both that extraordinary circumstances occurred and that reasonable measures could not have avoided the disruption. The passenger does not have to prove the reverse.
Second, the two conditions are joined by "and," not "or." Both have to be satisfied. Extraordinary circumstances alone are not enough. The airline must also address the reasonable measures question.
Third, the standard is "all reasonable measures." Not some measures. Not the measures the airline happened to take. All reasonable measures. This is a demanding standard, and it applies specifically to the disruption in question, not to the airline's operations in general.
The Court of Justice of the European Union has repeatedly emphasized these features of the regulation. The airline is not excused from compensation simply because a difficult event occurred. It is excused only if the event occurred and the airline can prove that reasonable measures would not have avoided the resulting disruption.
See: What Extraordinary Circumstances Actually Means Under EU261: A Complete Reference
The two-part test structure
For any extraordinary circumstances defense, two independent questions have to be answered in the airline's favor for the defense to succeed.
Part one: does the event qualify as extraordinary? This is the taxonomic question addressed in the extraordinary circumstances reference article. Different categories of event (weather, technical, ATC, strikes, security) have different requirements for qualification. Some categories qualify only in narrow circumstances. Others rarely qualify at all. The airline has to satisfy this question first.
Part two: could reasonable measures have avoided the disruption? Even where the event qualifies as extraordinary, the airline has to establish that it could not have avoided or mitigated the impact through reasonable operational responses. This is a separate analytical question. The event may be extraordinary and the airline may still be liable if reasonable measures would have prevented the delay or cancellation from affecting the passenger's flight.
Both questions have to be answered in the airline's favor. If either fails, the defense fails, and the compensation obligation stands.
Airlines routinely address only part one. The rejection letter identifies the extraordinary event, cites the regulation, and treats the matter as closed. The reasonable measures question is left unaddressed, as if the extraordinary nature of the event alone were sufficient. Under the regulation, it is not.
What counts as reasonable measures
The reasonable measures test asks what the airline could have done to avoid the disruption or mitigate its impact on the specific flight in question. The scope of possible measures depends on the specific scenario, but several categories recur across most cases.
Repositioning aircraft. Airlines operate networks with multiple aircraft, and disruption to one aircraft can often be mitigated by reallocating another aircraft to the affected route. Where a spare aircraft was available or could have been made available with reasonable operational effort, and the airline did not use it, the reasonable measures test has not been satisfied.
Adjusting crew schedules. Crew availability is often the binding constraint in disruption recovery. Reasonable measures include adjusting rest periods within legal limits, calling in reserve crew, and reallocating crew across the network to cover affected flights.
Arranging alternative routing. For cancellations, the airline is expected to consider whether the passenger could have been rebooked through a different route. This includes connecting flights, alternative airports, and even routing through partner carriers.
Using spare aircraft or capacity. Larger airlines maintain spare aircraft specifically for disruption recovery. Failing to use available spare capacity when it existed is a reasonable measures failure.
Coordinating with other carriers. In some circumstances, buying passengers seats on other airlines is a reasonable measure. This is especially relevant for cancellations where the airline's own network cannot restore service in a reasonable timeframe.
Buffer time and scheduling. The Court of Justice has held that airlines are expected to build reasonable operational buffers into their schedules. A disruption that could have been absorbed by reasonable buffer time but was not because the airline scheduled too tightly is a reasonable measures failure even if the underlying cause was extraordinary.
The specific measures that count as reasonable depend on the specific scenario. What matters is that the airline has to consider them, has to be able to prove which ones were evaluated, and has to explain why the measures it considered were insufficient. Silence on any of this is not a neutral posture. It is a failure to satisfy the second half of the test.
How the test applies across different scenarios
The reasonable measures analysis shifts depending on the type of extraordinary circumstance being invoked.
For weather-based defenses, reasonable measures typically include repositioning aircraft or crew ahead of predicted disruption, delaying operations rather than cancelling, and rebooking passengers on later flights. Iberia's weather rejection in a previous article failed on both the substantive question (weather affecting a previous flight, not the flight in question) and on the reasonable measures analysis (no evidence that repositioning could not have restored operations).
For technical defenses, the reasonable measures analysis considers whether spare aircraft was available, whether the airline maintains adequate maintenance capacity, and whether the disruption could have been resolved through reallocation. Most technical defenses fail on the qualification question (routine maintenance issues are not extraordinary), but even the narrow cases that pass the first test still face the reasonable measures analysis on the second.
For ATC and airspace restrictions, reasonable measures include alternative routing, delayed departure to wait for the restriction to lift, and coordination with other carriers. NOTAM-based defenses in particular are subject to careful reasonable measures scrutiny, because the airline has to show not just that the restriction existed but that no reasonable response could have avoided the impact on the specific flight.
For strike defenses, the reasonable measures analysis was central to the TAP Portugal case discussed in a previous article. Even where the underlying strike was framed as extraordinary, the airline's failure to reposition aircraft and crew after the strike ended was an operational matter that could have been addressed through reasonable measures. The strike alone did not excuse the cancellation the following day.
For security incidents, reasonable measures typically involve rerouting, delayed operations, and coordination with airport and government authorities. As with NOTAM defenses, the airline has to show that no reasonable operational response could have avoided the specific disruption, not just that the underlying event occurred.
See: When Airlines Extend Strike Defenses Beyond the Actual Strike, When Airlines Blame Weather to Deny Compensation
The burden of proof sits on the airline
The single most important feature of the reasonable measures test is that the burden of proof is entirely on the airline. The passenger does not have to prove that reasonable measures would have avoided the disruption. The airline has to prove that no reasonable measures could have.
This distinction matters enormously in practice. It means that when the airline's rejection letter is silent on reasonable measures, the airline has not met its burden. The passenger does not need to point to specific measures the airline should have taken. The passenger needs to point out that the airline has not addressed the question at all.
The Court of Justice has been clear that this burden requires actual evidence, not general assertions. The airline has to show what measures were considered, what evidence supports the conclusion that they were insufficient, and what specific operational constraints made the disruption unavoidable. Statements like "no reasonable measures could have been taken" or "the disruption was unavoidable" without supporting evidence are legally inadequate.
For challenging a rejection, this creates a clear practical opening. When the airline cites extraordinary circumstances without addressing reasonable measures, the response is to ask specifically what reasonable measures the airline considered, what evidence supports the conclusion that they were insufficient, and what operational analysis was performed. In many cases, no answer is provided because no analysis was ever done.
Real examples from case law
The reasonable measures framework has been developed and refined through a series of significant CJEU rulings.
Wallentin-Hermann v. Alitalia (Case C-549/07, 2008) established the modern framework by holding that technical problems inherent to the normal exercise of airline activity are not extraordinary circumstances, and that even where extraordinary circumstances are established, the airline must separately prove that reasonable measures could not have avoided the disruption. This case is the foundation of the entire two-part test structure.
Sturgeon v. Condor (Cases C-402/07 and C-432/07, 2009) confirmed that long delays trigger the same compensation regime as cancellations and clarified that the reasonable measures analysis applies to delays in the same way it applies to cancellations. This significantly expanded the practical importance of the reasonable measures test.
Eglītis v. Latvijas Republikas Ekonomikas ministrija (Case C-294/10, 2011) is particularly important for reasonable measures analysis. The Court held that airlines are expected to plan reasonable buffer time into their schedules to accommodate potential disruptions. A tight schedule that provides no ability to recover from disruption is not consistent with reasonable measures.
Corina v. Alitalia (Case C-315/15) and subsequent bird strike cases confirmed that even where a bird strike qualifies as extraordinary, the airline still has to prove that reasonable measures were taken to prevent the disruption from propagating to the affected flight. Simply pointing to the bird strike is not sufficient.
Across all of these rulings, the pattern is consistent. The extraordinary event is not the end of the analysis. It is the beginning. The reasonable measures question is where most defenses actually succeed or fail.
How to challenge a rejection using the reasonable measures test
For passengers who have received an extraordinary circumstances rejection, the reasonable measures test provides a specific and effective basis for challenge.
The response to a rejection that cites extraordinary circumstances without addressing reasonable measures should request specifically that the airline produce evidence of the reasonable measures analysis. This includes what measures were considered (repositioning, alternative routing, crew reallocation, etc.), what evidence supports the conclusion that each was insufficient, and what specific operational constraints made the disruption unavoidable despite these considerations.
In many cases, the airline cannot produce this evidence because the analysis was never performed. The rejection was generated based on the fact of the extraordinary event alone, without any assessment of whether reasonable measures could have avoided the disruption. Where the airline cannot produce the analysis, the defense fails on the second half of the test regardless of whether the first half was satisfied.
Where the airline does produce a reasonable measures analysis, that analysis can then be evaluated on its merits. Was the range of measures considered adequate? Was the evidence supporting the conclusion that measures were insufficient actually flight-specific? Did the analysis address the specific operational constraints that would have applied at the time?
The passenger who understands the two-part structure is significantly better positioned to challenge rejections than the passenger who only knows that extraordinary circumstances exists as a concept. The extraordinary circumstances question is where airlines fight. The reasonable measures question is where they often quietly lose.
See: How Claim Catalyst Handles Airline Resistance, Why Escalation Is Sometimes Required
Bigger picture
The reasonable measures test is what prevents the extraordinary circumstances exception from becoming a general escape clause. Without it, any airline could point to any real-world event that plausibly affected its operations and treat the matter as closed. The result would be a compensation regime that pays out only in the narrow cases where airlines cannot identify any external factor at all.
The regulation was written to prevent this outcome. By requiring the airline to prove both that extraordinary circumstances occurred and that reasonable measures could not have avoided the disruption, the regulation ensures that airlines cannot escape liability simply by identifying a difficult event. They also have to show that they responded appropriately.
Most airlines do not engage with the second half of the test in initial rejections. This is a strategic choice. It reduces the volume of claims that get pursued past the initial denial. Passengers who accept the rejection at face value abandon claims that would have succeeded if pushed. Passengers who challenge the rejection on reasonable measures grounds often find that the airline cannot sustain the defense when actually tested.
Understanding this is what separates a passenger who accepts a rejection from a passenger who forces the airline to complete the defense the regulation actually requires. It is one of the most reliably effective analytical tools in airline compensation, and it applies to essentially every extraordinary circumstances rejection.
See: What Claim Catalyst Actually Does For You
Frequently asked questions
What is the reasonable measures test under EU261?
The reasonable measures test is the second half of the extraordinary circumstances defense under Article 5(3) of EU261. Even when an airline proves that an extraordinary event occurred, it must also prove that reasonable operational measures could not have avoided or mitigated the disruption. The airline has to satisfy both requirements to escape the compensation obligation. Silence on the reasonable measures question means the defense is incomplete.
Does the airline have to prove they took reasonable measures?
Yes. The burden of proof sits entirely on the airline. The passenger does not have to identify specific measures the airline should have taken. The airline has to prove which measures were considered, why each was insufficient, and what operational constraints made the disruption unavoidable. General assertions are not sufficient. The Court of Justice of the European Union has been clear that actual evidence is required.
What counts as a reasonable measure?
Reasonable measures include repositioning aircraft, adjusting crew schedules within legal limits, arranging alternative routing, using spare aircraft, coordinating with partner carriers, buying passengers seats on other airlines, and building reasonable buffer time into operational schedules. What counts as reasonable depends on the specific scenario and the airline's operational capacity, but the airline is expected to consider the full range of possible responses.
Can I challenge a rejection that cites extraordinary circumstances?
Yes, and the reasonable measures test is often the strongest basis. If the airline's rejection identifies an extraordinary event but does not address what reasonable measures were considered and why they were insufficient, the defense is legally incomplete. Requesting specifically that the airline produce evidence of the reasonable measures analysis is often enough to expose that no analysis was actually performed.
What if the extraordinary event genuinely qualified?
Even where the underlying event genuinely qualifies as extraordinary, the reasonable measures test still applies. The airline still has to prove that no reasonable operational response could have avoided the disruption. A qualifying event does not automatically excuse the airline. The reasonable measures question is a separate analytical requirement that has to be satisfied on its own terms.
How does the reasonable measures test apply to weather delays?
For weather-based defenses, reasonable measures typically include repositioning aircraft or crew ahead of predicted disruption, delaying operations rather than cancelling, and rebooking passengers on later flights. Even where the weather itself qualifies as extraordinary, the airline has to prove that these operational responses could not have avoided the impact on the specific flight. Failure to address these measures is a common reason weather-based defenses fail.
If you have received an extraordinary circumstances rejection and want to understand whether the airline has actually satisfied both halves of the defense the regulation requires, Claim Catalyst evaluates every rejection against the full two-part test and identifies the specific gaps that can be challenged. Start a claim or learn more about how airline defenses are evaluated against the actual legal standard.