The three things the airline must prove

Reciting the phrase is not enough. To reduce or refuse compensation, an airline has to establish all three of these:

  1. A specific event. Not "operational reasons", not "unforeseen circumstances", not "a knock-on effect". The actual thing that happened.
  2. That the event was outside their control. Something they could not have prevented with the resources a carrier normally has.
  3. That no reasonable measure could have avoided the delay. This is the part most refusals skip entirely. Even when the event is genuine, the airline must show it could not have rebooked you, swapped aircraft or crewing to limit the delay.

If a refusal letter omits any of the three, it has not made the legal case. That is a legitimate and specific thing to challenge.

What can count

  • Severe weather that makes operating the flight unsafe — not routine winter conditions the airport handles normally.
  • Air traffic control restrictions, including strikes by air traffic controllers and airport or airspace closures.
  • Security risks, such as a credible threat or a security breach that closes a terminal.
  • Political instability or civil unrest that closes airspace or an airport.
  • Bird strikes, in some circumstances, where the damage genuinely could not have been anticipated.
  • A hidden manufacturing defect identified by the manufacturer or a regulator, affecting the whole fleet.

What usually does not count

This list matters more than the previous one, because it is where refusals fall apart:

  • Routine technical faults. The Court of Justice has held that a technical problem does not by itself amount to extraordinary circumstances. Ordinary reliability issues are part of running an airline.
  • Late arrival of the aircraft from a previous rotation, where the root cause was within the airline's control.
  • Crew shortages and rostering problems — including a shortage caused by the airline's own planning.
  • Strikes by the airline's own staff. These are generally treated as within the airline's control, unlike strikes by air traffic control or airport staff.
  • Overbooking. Deliberately selling more seats than exist is a commercial decision.
  • "Operational reasons" as a catch-all. It identifies nothing, so it proves nothing.

The distinction that decides most cases

Was the cause inside the airline's own operation, or outside it? Weather, ATC and security sit outside. Aircraft reliability, crewing and scheduling sit inside. Most disputes turn on where a specific event falls, not on the wording of the regulation.

What you still get when the airline is right

This is the part passengers most often miss. Even where extraordinary circumstances are properly established and compensation falls away, other rights usually remain:

  • Care and assistance — meals and refreshments proportionate to the wait, and two communications.
  • Accommodation and transfers if you are stranded overnight.
  • Reimbursement of care costs the airline failed to provide, on production of receipts.
  • For cancellations: the choice between a refund and rerouting.

These are separate rights with separate claims. A refusal letter about compensation does not answer them, and it is common for a passenger to accept a refusal on compensation while never claiming the hotel they paid for themselves.

How to challenge a vague refusal

Do not argue the law at length. Ask for the three things:

You have relied on extraordinary circumstances. Please identify the specific event, explain why it was outside your control, and explain what reasonable measures you considered to avoid the delay.

Please also confirm whether you will reimburse the care costs I incurred, which I understand are separate from compensation.

A precise question is hard to answer with a template. Airlines typically respond either by paying or by producing a real explanation.

Evidence worth gathering

  • The airline's refusal letter, in full.
  • Your original claim and proof of when you sent it.
  • The actual arrival time — airline flight status, airport board, or your own records.
  • Any weather or NOTAM records for the airport and date, if weather is cited.
  • Receipts for meals, transfers and hotels you paid for.

Questions

Is a technical fault extraordinary?

Usually not. A routine technical problem is treated as part of normal airline operation. A hidden manufacturing defect identified by the manufacturer or a regulator can qualify.

Is a staff strike extraordinary?

The airline's own staff striking is generally not treated as extraordinary. Strikes by air traffic control or airport staff usually are.

Who decides?

The airline asserts it, but it bears the burden of proof. If it refuses, the national enforcement body can require it to justify the position.

Do I lose everything if they are right?

No. Care, assistance, accommodation and — for cancellations — refund or rerouting normally remain available.

Official sources