EU261 compensation: how courts define “extraordinary circumstances” for airlines

Under EU261, an airline can avoid paying up to €600 compensation only if it proves two things: the disruption came from an event outside its normal operations and beyond its control, and even taking all reasonable measures could not have prevented the delay or cancellation.

Routine technical faults and internal staff strikes do not qualify. Bird strikes and mandatory air traffic decisions can, but only when the airline shows a real mitigation effort.

One vague sentence, rebuilt by the courts

The legal anchor is Article 5(3) of Regulation (EC) No 261/2004. It says a carrier does not have to pay if it can prove the cancellation or long delay came from extraordinary circumstances that could not have been avoided even if all reasonable measures had been taken. That sounds simple. It is not.

The Court of Justice of the European Union never wrote a master list. Instead, it built a two-limb test from a series of references. The event must fall outside the airline’s normal activities. And it must remain beyond the airline’s actual control. Those are separate questions, and the court applies both. The burden sits with the airline from the first moment: it must prove the event was extraordinary and that it took every reasonable step to limit the damage.

What the courts excluded: the business-risk principle

The clearest line runs through technical defects. In Wallentin-Hermann v Alitalia, an unexpected engine problem grounded the argument that airlines face ordinary operational risk every day. The court held that technical problems and component failures arising from normal maintenance and operations are inherent in airline activity, even when a specific failure surprises the engineering team. Later decisions applied the same logic to on-condition parts and crew illness.

Staff strikes caused by internal restructuring fall on the same side. In Krusemann and others v TUIfly, a sudden walkout triggered by corporate restructuring was treated as a predictable consequence of managerial decisions, not an external event. The UK Supreme Court reached a similar conclusion in Lipton and another v BA Cityflyer Ltd. Two passengers on a Milan–London flight fought a refusal based on crew illness, and the court held that illness among staff is simply a normal business risk. As the UK Supreme Court made clear, crew availability is part of running an airline, not an event outside it.

What can qualify — and the mitigation trap

A bird strike sits on the other side of the line. In Pešková and Peška v Travel Service, the court reasoned that a bird colliding with an aircraft is external to the carrier and not inherent in normal operations. But the airline still had to show it took all reasonable measures to avoid or mitigate the resulting delay. That second step is where many defenses fail.

January 2026 brought the most recent addition. In Case T-134/25, the General Court held that mandatory air traffic management or ATFM slot decisions imposed by control authorities can be extraordinary circumstances if they were outside the carrier’s control and directly caused the delay, regardless of how long that delay lasted. According to the EUR-Lex (European Union Law) record, the ruling applies even when the resulting delay is below three hours or hits an earlier rotation of the same aircraft.

The trap for airlines is mitigation. Courts have refused to accept an external event like a bird strike or an air traffic restriction when the carrier failed to use available alternative flights or resources. Claims have succeeded against airlines on exactly this ground, because proving the event was extraordinary is only half the job.

Rotations, causation, and the three-hour arithmetic

The three-hour rule comes from Sturgeon. An arrival delay of three hours or more is treated like a cancellation for compensation purposes, even though the regulation’s text mentions cancellation explicitly. That expanded the scope of EU261 compensation in ways airlines still argue about.

What counts as the delay itself has also been stretched. In Transportes Aéreos Portugueses, the court said an airline can rely on an extraordinary circumstance affecting a previous flight operated by the same aircraft if a direct causal link exists. Austrian Airlines pushed the chain further, allowing an event several rotations earlier to feed into the defense. The causal link must be clean, though. A weak chain of causation usually collapses on close inspection.

The 2026 air traffic decision added a nuance that matters enormously. If an extraordinary portion is deducted from a complex delay and the remaining airline-attributable delay falls below three hours, compensation is not due. Passengers can still win if the deduction leaves enough delay that is not explained by a proven external cause.

Brexit, national enforcement, and the thin paper trail

The UK did not abandon EU261 after Brexit. The UK Supreme Court confirmed in Lipton that Regulation 261’s EU text continues as retained domestic law. UK courts keep applying the same restrictive extraordinary-circumstances framework developed by the CJEU. Norway, Iceland, and Switzerland have adopted similar protections and treat the EU case law as persuasive, though detailed named enforcement decisions from those countries are scarce in public databases.

What about the claim that national enforcement bodies in the EU read the same rulings unevenly? The public paper trail is thinner than the commentary suggests. No publicly-verifiable decisions from bodies such as the UK CAA, Germany’s Luftfahrt-Bundesamt, or the Dutch ILT were located showing named divergences on identical extraordinary-circumstances events. That does not mean practice is uniform. It means the evidence is not yet in the open record, and a passenger who files in one member state may still face a different outcome than one who files elsewhere.

How the defence actually works at claim time

An airline cannot simply label a day “extraordinary” and push the claim away. It must prove both limbs: the event was outside normal operations and beyond its control, and it took every reasonable measure to avoid the delay or cancellation. The passenger never has to prove why the flight went wrong.

That second limb trips up more claims. In practice, courts have refused the defence where the airline failed to use available alternative flights, rebooking options, or other resources. Lipton is the clearest example. BA Cityflyer tried to refuse compensation for a 2016 Milan–London delay caused by crew illness. The case moved through the County Court and the Court of Appeal before the UK Supreme Court held that crew illness falls within normal business risk. The passengers won.

Even when an airline successfully proves extraordinary circumstances, its duties do not vanish. It still owes meals, hotel accommodation where needed, and the choice of a refund or rerouting. The compensation cheque may disappear, but care and support obligations remain.

What this means for you

When an airline denies compensation, ask for two things in writing: proof that the event was outside its normal operations and beyond its control, and a timeline showing every reasonable measure it took. A technical fault alone is almost never enough. A bird strike denial is valid only if the airline shows a genuine mitigation effort.

If an air traffic management decision is used to reduce your delay below three hours, ask for the causal breakdown. The airline must show which portion is attributable to the external decision and which portion remains its own. If the chain is fuzzy, challenge it.

UK passengers should know the retained law tracks the EU framework, so the same reasoning applies. And where enforcement is uneven, the practical move is to escalate beyond the first denial — through a national enforcement body or court — rather than accept a generic refusal.

Questions? Answers.