Extraordinary Circumstances Under EU261 — What Counts and What Doesn't

What are ‘extraordinary circumstances’ under EU261?

Extraordinary circumstances are events outside the airline’s reasonable control that could not have been avoided even if all reasonable measures had been taken. The category is defined in the regulation’s recitals as including things like political instability, meteorological conditions, security risks, unexpected safety shortcomings, and strikes affecting operation. It has been substantially refined by Court of Justice rulings since 2005.

The legal test, developed across many CJEU cases, has two parts:

1. The event must be outside the airline’s normal commercial activity — not an event that is part of normal operations or that the airline should reasonably anticipate.

2. The event must not have been avoidable by reasonable measures the airline could have taken. The airline must demonstrate it took all reasonable steps to prevent or mitigate the disruption.

Both parts must be satisfied. An event can be unusual but still avoidable through reasonable planning. Conversely, an event that was unavoidable in the moment may have been preventable through earlier planning. The CJEU has been generally strict in applying this test, finding many initial airline defences to be inadequate.

The defence applies only to the cash compensation obligation, not to the care obligation (food, drink, hotel, etc.) or to the refund/rerouting right. Even where an extraordinary circumstance is established, the airline must still provide care and offer the passenger a refund or rerouting.

What counts as extraordinary?

The major categories of events that generally do count as extraordinary, when they directly affect the specific flight:

Severe weather. Heavy snow, fog, thunderstorms, hurricanes, and other meteorological conditions that prevent safe operation. The weather must directly affect the flight in question — generic weather elsewhere does not qualify.

Air traffic control restrictions. ATC strikes, capacity restrictions, slot delays imposed by air traffic management. These are imposed by third parties on the airline and are outside its control.

Airport closures. Closure of the origin or destination airport for security, safety, or weather reasons. Includes runway closures for incidents.

Security incidents. Bomb threats, security investigations, terror incidents, and broader security alerts that affect operations.

Political instability. War, civil unrest, coups, government-imposed flight bans, or other geopolitical disruption affecting the route.

Strikes by third parties. Air traffic controller strikes, airport ground staff strikes (when the ground staff are not employed by the airline), security personnel strikes, fuel supplier strikes. These are imposed on the airline rather than caused by it.

Bird strikes. The CJEU specifically ruled in Pešková v Travel Service (2017) that a bird strike requiring inspection is generally an extraordinary circumstance, provided the airline reasonably managed the situation.

Hidden manufacturing defects. Aircraft defects that are inherent to the design or that emerge from a manufacturing fault outside the airline’s knowledge — typically requiring fleet-wide recall by the manufacturer. This is a narrow category and rarely invoked successfully.

Medical emergencies. A passenger or crew member emergency requiring diversion or delay generally qualifies as extraordinary.

What does NOT count as extraordinary?

The categories of events that have been consistently held NOT to be extraordinary circumstances:

Routine technical and mechanical issues. The Wallentin-Hermann ruling (2008) established that ordinary technical problems with the aircraft — even ones that emerge suddenly and could not be predicted on the day — are part of the airline’s normal commercial activity. The airline is expected to maintain its fleet to a standard that anticipates technical issues. Only hidden manufacturing defects (not normal wear-and-tear or maintenance issues) qualify.

Strikes by the airline’s own staff. Multiple CJEU rulings (Krüsemann 2018, TAP Portugal 2024, and others) have established that strikes by an airline’s pilots, cabin crew, ground staff, or other employees are NOT extraordinary circumstances. The airline employs these staff and has tools (negotiation, scheduling, contingency planning) to manage labour relations. Wildcat strikes are also covered by this principle.

Crew shortages. If the airline does not have enough crew to operate the flight — whether due to illness, scheduling, or earlier delays — this is generally an operational issue within the airline’s control. Crew shortages are not extraordinary.

Knock-on delays from earlier disruption. If the same aircraft was delayed on an earlier rotation and the later flight is consequentially delayed, the original delay’s extraordinary status (if any) does not automatically transfer. The airline must demonstrate the connection and that no reasonable measures could have been taken to recover the schedule.

Late arrival of an inbound aircraft from a non-extraordinary cause. The TUI v Skyland (2013) line of cases established that downstream delays caused by upstream operational issues remain the airline’s responsibility.

Overbooking. Discussed in our denied-boarding article — overbooking is the airline’s commercial choice and never an extraordinary circumstance.

Does the airline have to prove it?

Yes. The burden of proof is firmly on the airline. The passenger does not have to prove that the disruption was within the airline’s control. The airline must prove that it was outside its control AND that all reasonable measures were taken.

This burden of proof is a significant practical advantage for passengers. Many initial airline rejections cite extraordinary circumstances without supporting evidence, and a passenger who pushes back firmly and asks for documentation often succeeds.

Specifically, the airline must provide evidence of: the extraordinary event itself (weather data, ATC restrictions, strike documentation, security incident reports); the causal link between the event and the specific disrupted flight; and the measures the airline took to mitigate the disruption. Generic statements such as “due to operational reasons” or “due to extraordinary circumstances” without specific evidence are typically insufficient.

National enforcement bodies and courts have repeatedly held that the airline’s evidentiary burden is real and meaningful. An airline that claims extraordinary circumstances without producing the underlying documentation generally loses the case on that ground alone. The proof requirements often surface during the claim process — at the initial submission stage, then at any escalation stage, with the bar getting higher at each step.

Is weather automatically extraordinary?

No. Weather is among the most common claimed extraordinary circumstances, but the analysis is more nuanced than “there was bad weather, therefore no compensation.” Several conditions must be met.

The weather must have directly affected the specific flight. Severe weather elsewhere — at the airline’s hub, at a different airport, on a different route — is not enough. The airline must show that the weather affected this flight’s operations.

The weather must have been such that operating the flight was not safely possible. A flight delayed because of forecast precipitation that did not actually materialise, or because of caution rather than a genuine impossibility, may not qualify.

The airline must demonstrate that reasonable measures were taken to mitigate. This often means: using alternative aircraft, alternative crew, alternative slots, or rebooking passengers on competitor flights when possible. An airline that did nothing and simply waited for the weather to clear may struggle to defend an extraordinary-circumstances claim.

Specific weather categories that almost always qualify: hurricanes and named storms with airport closure; widespread fog that closes runways; volcanic ash clouds; freezing fog combined with de-icing system failures (though this can shade into airline responsibility); ice storms shutting down ground operations.

Categories that often do not qualify: thunderstorms in summer at airports that routinely handle them; minor snow at airports that should be equipped for it; light fog that the airline could have planned around; routine crosswinds.

Are strikes extraordinary circumstances?

It depends entirely on who is on strike.

Third-party strikes are generally extraordinary. Air traffic controller strikes, airport ground handler strikes (where the handler is not employed by the airline), security personnel strikes, fuel supplier strikes — all of these are imposed on the airline by others and are outside its control.

Airline employee strikes are generally NOT extraordinary. The Krüsemann ruling (2018) and the TAP Portugal ruling (2024) have firmly established that strikes by pilots, cabin crew, maintenance staff, or other airline employees are part of the airline’s “normal management of its activities.” The airline employs these staff and has tools to manage labour relations.

This holds even for wildcat strikes (unauthorised strikes by employees without union backing). The CJEU has been consistent that the employment relationship and the airline’s management responsibility are what matter, not whether the strike was authorised.

The same principle applies to crew unavailability from non-strike causes — a crew member calling in sick, a crew member exceeding duty hours, a crew member missing a connecting flight. The airline is expected to have backup plans for normal staffing variation.

One edge case: sympathy strikes by airline employees in response to industrial action elsewhere may be treated differently depending on the facts. Passengers facing this should seek specific legal advice; the law is still developing.

What about technical and mechanical issues?

The general rule is that technical problems are NOT extraordinary circumstances. The Wallentin-Hermann ruling (2008) established the foundational principle: technical problems are part of the airline’s normal commercial activity. The airline is expected to maintain aircraft to a standard that anticipates ordinary technical issues.

This holds even for technical issues that emerge unexpectedly on the day of the flight. The Sandström v SAS line of cases confirmed that the unexpected nature of the problem does not make it extraordinary — the airline’s maintenance programme should account for the statistical likelihood of unexpected issues.

The narrow exception is “hidden manufacturing defects” — defects that are inherent to the aircraft design or production that emerge across the fleet and require manufacturer-level remediation. These typically require a formal safety bulletin or fleet-wide recall. Individual aircraft issues that emerge from normal wear-and-tear, missed maintenance, or expected component failure do not qualify.

The other narrow exception is damage from external events that are themselves extraordinary — a lightning strike, a bird strike, a runway debris incident, weather damage. Where the technical issue was caused by an extraordinary event, the underlying classification follows.

For passengers whose claims have been rejected on technical-issue grounds, the question to ask is: what specifically caused the technical issue, and was the cause itself extraordinary? Airlines that simply assert “technical issue” without specifying are typically not meeting the evidentiary burden.

What about air traffic control and airport closures?

ATC and airport closures are among the clearer extraordinary-circumstances categories. Air traffic management is imposed on airlines by third parties (national ATC providers, Eurocontrol) and is not within the airline’s control. Airport closures for security, weather, or other reasons are similarly imposed.

However, the airline must still demonstrate the specific impact on the flight. Generic ATC delays elsewhere in Europe do not exempt a specific flight; the airline must show how the ATC restriction affected this flight’s departure slot, en-route routing, or arrival.

The airline must also demonstrate reasonable mitigation measures. Where ATC delays are predictable (a planned ATC strike announced in advance, a known capacity restriction), the airline is expected to adjust schedules, swap aircraft, or take other measures to minimise the impact. An airline that did nothing in response to a foreseeable ATC restriction may struggle to defend an extraordinary-circumstances claim.

Knock-on delays from ATC restrictions are particularly contested. If a flight is delayed because the inbound aircraft was held up by ATC at an earlier airport, the airline must show both that the original delay was extraordinary and that no reasonable measures (substitute aircraft, schedule adjustment) could have prevented the knock-on. The chain often breaks at this evidentiary point.

What about knock-on delays affecting multiple flights?

The TUI v Skyland (2013) and subsequent cases have established that downstream delays caused by upstream issues remain the airline’s responsibility unless the airline can demonstrate that both the original disruption AND the downstream propagation were extraordinary and unavoidable.

This is a significant practical limitation on the extraordinary-circumstances defence. Airlines frequently experience cascading delays — one aircraft delay propagates through that aircraft’s rotation, affecting multiple flights through the day. The airline often points to an early-morning weather event as the “cause” of an evening delay.

The CJEU’s position is that the airline must show: the original disruption was extraordinary; the propagation through the schedule was unavoidable by reasonable measures (substitute aircraft, crew changes, schedule adjustments); the specific flight in question was directly affected by the original event rather than by intervening operational choices.

This is a high bar in practice. Many airline defences citing “earlier weather” or “earlier ATC restrictions” for evening delays have been rejected on the grounds that the airline had hours to adjust and chose not to take available mitigation steps.

Can an extraordinary-circumstances claim be challenged?

Yes, and successfully in many cases. The process for challenging an airline’s extraordinary-circumstances defence is straightforward in principle.

Step 1: Request documentation. Write back to the airline asking for specific evidence supporting the extraordinary-circumstances claim. This includes: details of the alleged event, evidence of its impact on the specific flight, and details of the measures taken to mitigate. Many airlines fold at this stage because the documentation does not exist or does not support their position.

Step 2: Escalate to the National Enforcement Body. If the airline maintains its position, file the dispute with the relevant national enforcement body (Civil Aviation Authority in the UK, the relevant national body in EU member states). The NEB will assess the airline’s evidence and issue a non-binding opinion.

Step 3: Court action. If the airline still refuses to pay, small claims court or the European Small Claims Procedure (for cross-border cases under €5,000) is the route. Court cases have been consistently favourable to passengers where airlines cannot meet the evidentiary burden.

The combination of these steps is what makes EU261 work in practice. Initial rejection rates from airlines are high. After NEB review and escalation, the eventual payment rate is much higher. Claims-management companies like AirHelp handle this entire escalation chain on a no-win, no-fee basis, which is why their commission structure (typically 35–50%) is justifiable for passengers who would not pursue the case themselves.

The practical bottom line: an airline citing extraordinary circumstances is the start of the negotiation, not the end. Passengers who push back firmly with the regulation in hand often succeed, particularly in the borderline categories like routine technical issues, airline staff strikes, and downstream knock-on delays.