Extraordinary Circumstances: What Airlines Must Prove (And How to Challenge the Evidence)

Airlines reject hundreds of thousands of valid EC261 compensation claims every year with a form letter citing "extraordinary circumstances." Most passengers accept the rejection. Most of them shouldn't.

Here's the critical fact that airlines rely on you not knowing: the burden of proof is entirely on the airline. Under EU law, it is the airline — not the passenger — that must prove that extraordinary circumstances existed, that those circumstances directly caused the disruption, and that all reasonable measures were taken to avoid it.

A vague rejection letter citing "extraordinary circumstances" without specifics is legally insufficient. This guide explains exactly what the airline must prove in each scenario, and how to challenge them.

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The Legal Test: Two Requirements Both Must Be Met

The CJEU established the definitive test for extraordinary circumstances in Wallentin-Hermann v Alitalia (C-549/07, December 2008):

Condition 1: The event must not be inherent in the normal exercise of the air carrier's activities

Condition 2: The event must be beyond the airline's actual control

Both conditions must be satisfied. An event that satisfies only one fails the test.

This two-part test is why most airline extraordinary circumstances defences fail. Technical faults satisfy neither condition (they are inherent in aviation and within the airline's maintenance responsibility). Crew shortages fail the second condition (staff management is within the airline's control). Weather sometimes satisfies both — but only when severe enough to actually prevent safe operations.

For a full overview of what counts and what doesn't, see Extraordinary Circumstances: When Airlines Don't Have to Pay. For landmark case law, see EC261 Court Victories: How Passengers Are Winning.

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Scenario 1: Technical Faults

Airlines' claim: Aircraft malfunction, hydraulic failure, engine fault, avionics problem — "a safety-critical technical fault."

The legal position: Technical faults are almost never extraordinary circumstances.

The CJEU confirmed in Wallentin-Hermann that technical problems are inherent to airline operations. Airlines know aircraft develop faults. They are responsible for maintenance schedules, technical standards, spare parts availability, and contingency aircraft. A fault that occurs in the course of normal operations — even a genuinely unexpected one — does not satisfy Condition 1.

The CJEU reinforced this in Van der Lans v KLM (C-257/14, September 2015): even a premature, unexpected component malfunction is not extraordinary because such failures are intrinsic to the operation of aircraft.

What the airline must prove (and usually can't):

• That the specific fault was caused by an external event (e.g., confirmed act of sabotage, or a hidden manufacturing defect affecting the entire fleet type)
• That the fault was not detectable by any reasonable maintenance check
• That the fault is categorically different from the wear-and-tear and malfunction events that occur in normal operations

How to challenge:

1. Ask the airline: "Please specify the exact nature of the technical fault and explain why it does not fall within your normal operational responsibility."
2. Ask: "Please provide documentary evidence that this fault was caused by an event external to normal aircraft operations."
3. Cite Wallentin-Hermann (C-549/07) and Van der Lans (C-257/14) explicitly in your challenge.
4. If they cannot distinguish the fault from normal operational failures, escalate to ADR.

Success rate for passengers challenging technical fault rejections: High. ADR adjudicators and courts consistently reject technical fault defences unless the airline can point to a genuinely external, extraordinary cause.

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Scenario 2: Weather Delays

Airlines' claim: "Adverse weather conditions," "fog," "storm," "strong crosswinds."

The legal position: Weather can be extraordinary — but only when it actually prevents safe operations.

Genuine severe weather events (volcanic ash, hurricanes, extreme snowstorms that shut entire airports, zero-visibility fog preventing safe landing) are accepted as extraordinary circumstances by courts. The key is that the weather must have actually prevented the airline from operating safely — not merely caused inconvenience or minor delays.

What the airline must prove:

1. The specific weather conditions at the relevant airport and time. Not general "adverse weather" — the actual meteorological data showing what conditions were.

2. That the conditions prevented safe flight operations. This is a high threshold. An airline cannot cite weather if other flights operated normally at the same airport during the same time window.

3. That all reasonable measures were taken. Did the airline check the forecast? Was an alternative routing considered? Was a delay to avoid the conditions feasible?

How to challenge:

1. Check the actual weather data. Use Wunderground Historical Weather or Meteoblue Archive to get historical conditions for the specific airport and time.

2. Check what other flights did. On Flightradar24 or FlightAware, search for other flights departing from or arriving at the same airport during the same window. If dozens of other flights operated normally, the weather cannot have prevented operations.

3. If other flights flew, challenge it. "Please explain why your flight was prevented by weather conditions when [list of other flights] operated normally from the same airport during the same period."

4. For volcanic ash, severe storms, complete airport shutdowns: These are genuine extraordinary circumstances. Monetary compensation is not owed but the right to care (meals, hotel, transport) survives — confirmed in McDonagh v Ryanair (C-12/11, 2013).

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Scenario 3: Air Traffic Control (ATC) Restrictions

Airlines' claim: "ATC restrictions," "air traffic control delays," "ATFM slot restrictions."

The legal position: Genuine third-party ATC decisions can be extraordinary — but ATC delays are heavily abused as a defence.

The CJEU has accepted that ATC strikes and specific ATC-imposed restrictions on individual aircraft can constitute extraordinary circumstances. But this has significant limits.

Genuine extraordinary ATC circumstances:

• Third-party ATC staff strikes (not the airline's own staff)
• ATC-imposed restrictions due to security incidents
• Exceptional airspace closures (e.g., military exercises closing routes)

What courts have questioned:

• General ATC congestion that airlines should anticipate and plan for, especially during peak travel periods
• Predictable ATFM delays at congested airports (e.g., summer delays at Athens, Nice, or Lisbon that are well-documented annually)
• ATC slot delays caused by the airline scheduling too tight a rotation, leaving no buffer for routine ATC delays

What the airline must prove:

1. A specific ATC decision applying to their specific aircraft on the specific day — not general congestion affecting the airport.

2. That the decision was imposed by a third-party ATC authority and could not have been avoided even with schedule adjustments.

3. That the resulting delay was not exacerbated by the airline's own operational decisions.

How to challenge:

1. Ask the airline: "Please identify the specific ATFM slot restriction or ATC decision that caused this delay, including the reference number and issuing authority."

2. Check the EUROCONTROL ATFM Delay Attribution data or the Network Manager Operations Centre delay statistics. EUROCONTROL publishes delay data showing whether delays at specific airports on specific days were ATC-attributable.

3. If the airline cites ATC congestion that has been documented as routine at that airport (many Mediterranean airports in summer), challenge whether this was genuinely unforeseeable and beyond the airline's control.

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Scenario 4: Crew Issues — Sickness, Shortages, Exceeding Hours

Airlines' claim: "Crew unavailability," "crew sickness," "crew exceeding maximum flying hours."

The legal position: Crew issues are almost never extraordinary circumstances.

Airline staff management is core to the operating air carrier's responsibilities. Ensuring adequate standby crew, managing roster compliance, and having contingency plans for crew sickness are inherent operational duties. Courts have consistently rejected crew-based extraordinary circumstances defences.

The CJEU in Krüsemann v TUIfly (C-195/17, April 2018) addressed the most borderline scenario — a spontaneous wildcat sick-out by crew after unexpected restructuring announcements. The court found this could be extraordinary in narrow circumstances, but only for genuinely unforeseeable spontaneous collective action. Routine crew sickness or standard shortages do not qualify.

What the airline would need to prove for crew issues to succeed:

• A completely spontaneous, unforeseeable collective action by crew that could not have been anticipated by any reasonable planning
• That the airline had taken all reasonable measures to have contingency crew available
• That the specific nature of the crew action was genuinely unprecedented

How to challenge:

1. Ask: "Please specify the exact nature of the crew unavailability and explain why it constitutes an extraordinary circumstance under C-195/17 (Krüsemann v TUIfly)."
2. Ask: "What contingency crew arrangements were in place and why were they insufficient?"
3. For standard crew sickness: cite multiple national court decisions rejecting this as extraordinary — it is well-established law.

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Scenario 5: "Previous Flight" or "Knock-On" Delays

Airlines' claim: "Your flight was delayed because the inbound aircraft was late," "caused by previous flight delay."

The legal position: Knock-on delays do not transfer the extraordinary circumstances defence unless the original cause was extraordinary.

If your flight is delayed because the aircraft came in late from a previous rotation, the relevant question is: why was the previous flight delayed? If that delay was caused by something that is itself not extraordinary (technical fault, crew issues, etc.), the knock-on delay also doesn't qualify.

What the airline must prove:

• That the underlying cause of the original delay constituted extraordinary circumstances
• That the extraordinary circumstances on the earlier flight directly caused the delay to your flight
• That all reasonable measures were taken, including whether a substitute aircraft could have been deployed

How to challenge:

1. Ask the airline: "What specific extraordinary circumstance caused the delay to the inbound aircraft? Please provide documentary evidence."
2. If the underlying cause was a technical fault: cite Wallentin-Hermann — knock-on from a technical fault cannot become extraordinary.
3. Ask: "What steps were taken to source a substitute aircraft to avoid the cascade delay?"

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Scenario 6: "Security" Issues

Airlines' claim: Bomb threat, suspicious package, security screening evacuation.

The legal position: Genuine security incidents can be extraordinary, but airlines must prove the specific nature of the threat.

Verified security incidents — bomb threats requiring aircraft inspection and evacuation, discovery of dangerous items requiring police involvement, passenger behaviour creating genuine security risks — have been accepted by courts as extraordinary circumstances.

However, an airline cannot simply claim "security reasons" without specifics. They must establish that a real security event occurred that required the delay.

How to challenge:

1. Ask for documentation: "Please provide the incident reference number and confirming report from airport security authorities."
2. Check news reports for the airport on that day. Genuine security incidents at airports typically generate public records.
3. If no verifiable security incident occurred, challenge the extraordinary circumstances claim.

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Scenario 7: Political Unrest / Airspace Closures

Airlines' claim: Political instability, airspace closure due to conflict, government-imposed restrictions.

The legal position: Genuine political instability and government-imposed airspace closures are accepted extraordinary circumstances. These events are by definition external to the airline's operations and entirely beyond their control.

Examples that have been accepted: airspace closures over conflict zones, government-imposed restrictions due to political crises, sudden closure of foreign airspace to certain carriers.

Unlike weather or technical faults, these are difficult for passengers to challenge and genuinely extraordinary. Where these apply, compensation is not owed, but the right to care remains.

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The Three-Step Evidence Challenge Framework

When any airline rejects your claim citing extraordinary circumstances:

Step 1: Force specificity

Write to the airline:

"I am writing to formally contest your rejection of my EC261 compensation claim citing extraordinary circumstances. Please provide within 14 days: (a) The specific nature of the extraordinary circumstance claimed (b) The time and place of the extraordinary event (c) Documentary evidence that the event existed (d) An explanation of why the event was not inherent in your normal operations (e) An explanation of what reasonable measures were taken to avoid the delay"

Step 2: Cross-reference the facts

Independently verify the airline's claims using:

• Flight tracker data (Flightradar24, FlightAware) for actual flight details
• Weather archives for actual conditions at the airport and time
• News archives for any reported incidents
• EUROCONTROL ATFM delay data for ATC attributions

Step 3: Apply the legal test

For each claimed extraordinary circumstance, apply the Wallentin-Hermann two-part test:

• Is this event inherent in normal airline operations? (If yes → not extraordinary)
• Is this event beyond the airline's actual control? (If no → not extraordinary)

If the claim fails either test, your compensation entitlement stands. Escalate to ADR or NEB.

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What Happens When You Escalate?

ADR bodies and courts apply the same legal tests. The airline must provide documentary evidence of extraordinary circumstances to an ADR adjudicator — they cannot rely on the same vague letters that passengers too often accept.

Published data shows:

• 69% of Dutch court judgments in EC261 cases favour passengers
• 57% of UK ADR decisions favour passengers
• 81% of BA complaints escalated to an independent body were upheld

The evidence threshold at ADR is the same as in court. Airlines that cannot prove extraordinary circumstances with actual documents — not form letters — lose.

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Summary: Extraordinary Circumstances Quick Reference

Scenario	Extraordinary?	How to Challenge
Technical fault / mechanical failure	❌ Rarely	Cite Wallentin-Hermann; demand proof it was external
Routine crew sickness / shortage	❌ No	Demand proof of specific unforeseeable event
Aircraft late from previous rotation	❌ Usually not	Ask what caused the original delay; apply same test
Severe weather (genuine)	✅ Usually	Accept if airport was actually shut; challenge if others flew
Third-party ATC strike	✅ Usually	Verify via EUROCONTROL data
Seasonal ATC congestion	❌ Often not	Challenge foreseeability at notoriously congested airports
Genuine security incident	✅ Usually	Request incident documentation
Political/airspace closure	✅ Yes	Genuine force majeure; care rights still apply
Wildcat (spontaneous) staff strike	⚠️ Possibly	Requires proof of truly unforeseeable spontaneous action
Official trade union strike	❌ Usually not	Foreseeable; airline must have contingency plans

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Start Your Claim

If your airline cited extraordinary circumstances and you're not sure whether the rejection is valid:

1. Check your flight at FlightOwed — free eligibility check in 30 seconds
2. Use the Three-Step Evidence Challenge Framework above to formally request documentation
3. If the airline can't substantiate the claim, escalate to ADR

You have the law, the case precedent, and the burden of proof on your side.

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Related guides: Extraordinary circumstances — full overview · EC261 court victories and case law · ECJ ruling: pilot illness not extraordinary · Which airlines reject the most claims · What are extraordinary circumstances? · EC261 complete guide

Frequently Asked Questions

What evidence do I need to prove a delay was NOT extraordinary circumstances?

You don't need to prove anything — the burden of proof is entirely on the airline. They must demonstrate the specific extraordinary event, provide evidence of when it occurred, and show the steps taken to minimise its impact. Your job is simply to challenge inadequate responses and demand specifics.

Where can I find independent evidence of what caused my flight delay?

Several sources: Flightradar24 and FlightAware for aircraft movement data; Eurocontrol's Network Manager for ATC-related delays; airport authority reports for ground disruption; weather archives (Weather Underground, Wunderground, national meteorological services) for weather events; aviation incident databases for technical issues that became public.

What's the difference between weather causing a delay vs. weather as extraordinary circumstances?

Not all weather causes extraordinary circumstances. Scheduled weather forecasts (e.g., known winter storms) that the airline failed to plan for may not qualify. Weather must be genuinely unexpected and sufficiently severe. A slight headwind or light rain that wouldn't normally cause a 4-hour delay is not extraordinary — it may indicate an underlying operational failure.

How do I request the airline's evidence for their extraordinary circumstances claim?

Write formally (email or letter) requesting: the specific nature of the extraordinary circumstance, date and time of occurrence, documentation from relevant authorities (ATC, meteorological services, etc.), and a list of measures taken to avoid or minimise the impact. They are legally obligated to provide this; failure to do so undermines their defence.

Can an ATC strike at one airport affect my flight at a completely different airport?

Yes — ATC disruptions can cascade. However, the airline must demonstrate the specific causal link between the ATC event and your specific flight's delay. "There was an ATC issue somewhere in Europe" is not sufficient. The event must have directly affected your flight's routing or slot allocation.

What's the deadline for gathering evidence and filing a claim?

National statute of limitations apply — typically 2–3 years from the flight date in most EU countries. However, aviation data archives (especially Flightradar24) only retain certain data for limited periods. Act as soon as possible — ideally within 6–12 months of the disruption while data is still accessible.

Does using a professional service help with evidence gathering?

Significantly. Services like FlightOwed have access to professional aviation databases, established relationships with evidence providers, and experience identifying the specific documentation needed to challenge extraordinary circumstances defences. They know which sources courts find credible and how to present evidence effectively.