Extraordinary circumstances: when an airline can refuse flight compensation — and when it cannot

What the law actually says

Article 5(3) of Regulation 261/2004 — identical in UK261 — exempts the airline from compensation when 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”. The Court of Justice extended it to long delays in Sturgeon and Nelson and, in Wallentin-Hermann (C-549/07), gave the test its two parts:

1. The event must be extraordinary — not inherent in the normal exercise of the airline’s activity, and beyond its actual control.
2. Reasonable measures must have been unable to prevent it — the airline has to show what it did with the aircraft, crew and resources it had.

Both parts are for the airline to prove. You never have to disprove them. The exemption only touches the fixed compensation of Article 7: care, refund and re-routing have no extraordinary-circumstances clause, and denied boarding has no exemption at all.

Causes that usually count

Causes that never count

• Technical faults, including those discovered at the pre-flight check or during maintenance (Wallentin-Hermann; van der Lans, C-257/14). Aircraft break; that is inherent in running an airline.
• Crew sickness, absence or duty-time limits (TAP, C-156/22) — the airline is expected to plan reserves.
• Strikes by the airline’s own staff, whether lawful (Airhelp v SAS, C-28/20) or wildcat after a restructuring announcement (Krüsemann, C-195/17).
• Aircraft rotation and scheduling — a tight turnaround that collapses is the airline’s planning.
• The airline’s own IT failure (booking, check-in or crew-rostering systems).
• Overbooking — denied boarding has no exemption whatever the reason.
• “Operational reasons” — not a legal category; ask what actually happened.

The reasonable-measures test

A genuine extraordinary event is not the end of the analysis. The airline must also show it could not have avoided the delay to you — by using a spare aircraft or standby crew, re-routing you on its own next flight or on another carrier at the earliest opportunity, or repositioning resources. What is reasonable depends on the airline’s size and the cost: a network carrier at its hub is held to more than a small airline at an outstation, but nothing requires “intolerable sacrifices” (Wallentin-Hermann; Eglītis, C-294/10). If the airline had a spare aircraft parked at the airport and did not use it, the compensation is due even if the original cause was a storm.

Six realistic scenarios

Thunderstorms at Munich in the afternoon; your 19:00 departure leaves 3 h 30 late because the inbound aircraft was held. The weather was extraordinary for the inbound flight. For yours, the airline must prove the chain and explain why no spare aircraft at its own hub could operate — Munich is a Lufthansa base. Often compensable.

Lisbon ATC capacity regulation delays your Ryanair departure by 3 h 10. Genuine ATC flow restriction affecting that flight that day: extraordinary. No compensation; meals and refreshments were owed once the wait passed 2 hours.

Lufthansa cabin-crew strike cancels your flight three days before departure. Strike by the airline’s own staff: not extraordinary. €250–€600 plus refund or re-routing.

Hydraulic leak found at the pre-flight check, 4-hour delay. Technical: compensation due, full amount.

Bird strike on the inbound rotation; inspection takes 3 hours; no spare aircraft. Extraordinary under Pešková, provided the inspection was done promptly by qualified personnel. No compensation, care owed.

Fog closes London City for the morning; your flight is cancelled and you are rebooked for the next day. Extraordinary. No compensation — but the airline owes the hotel, transport and meals, and the refund if you prefer not to travel.

What you keep when the circumstance is genuine

• Care (Article 9): meals, refreshments, communication, hotel and transport, with no time or money limit even in a volcanic-ash crisis (McDonagh v Ryanair, C-12/11).
• Refund or re-routing (Article 8) for a cancellation or a delay of 5 hours or more — including on another airline where that is the earliest option.
• Expenses you had to pay because care was not provided.

How to test an airline’s “extraordinary circumstances” claim

Ask the airline in writing for three things: the specific event, the evidence that it affected your flight on that date, and the measures it took to avoid the delay. Then check what you can yourself: the flight’s history that day on a tracking site, whether other flights on the same route or from the same airport operated, and whether the strike, storm or closure it cites was real and in the right time window. A vague answer, or one that does not survive those checks, is what enforcement bodies and dispute schemes overturn. The rejection guide walks through the reply letter.