In short: A restriction imposed by air traffic control on your aircraft, a strike by air traffic controllers, or a failure of the air traffic system itself is usually an extraordinary circumstance, so no fixed compensation is due for the part of the delay it caused. If the aircraft missed its slot through the airline's own fault, or the ATC delay was only a small part of a longer delay, you may still be owed €250–€600 (EU261) or £220–£520 (UK261). Care, refunds and re-routing are due in every case.
What the law says
Recital 15 of Regulation (EC) No 261/2004 is unusually specific. Extraordinary circumstances "should be deemed to exist where the impact of an air traffic management decision in relation to a particular aircraft on a particular day gives rise to a long delay, an overnight delay, or the cancellation of one or more flights by that aircraft, even though all reasonable measures had been taken by the air carrier concerned to avoid the delays or cancellations".
Three conditions are built into that sentence: the decision must concern a particular aircraft on a particular day, it must cause the long delay or cancellation, and the airline must still have taken all reasonable measures. The European Commission's 2024 guidelines note that one air traffic management decision can produce several delays or cancellations.
Strikes are covered separately. Recital 14 mentions "strikes that affect the operation of an operating air carrier", and in Airhelp v SAS (C-28/20, 23 March 2021) the Court of Justice explained that the legislature meant strikes external to the airline's activity – so "strike action taken by air traffic controllers or airport staff may in particular constitute an extraordinary circumstance".
Is it extraordinary? ATC situations compared
| Situation | Extraordinary? | Authority |
|---|---|---|
| ATC capacity restriction or later slot imposed on your aircraft | Usually yes | Recital 15 |
| Strike by air traffic controllers | Usually yes | C-28/20 Airhelp v SAS (para. 42 of the judgment) |
| Failure of the national air traffic system (e.g. NATS, 28 August 2023) | Likely yes | CAA guidance, 30 August 2023 |
| Airspace closure (military activity, conflict, volcanic ash) | Usually yes | Recitals 14 and 15; C-12/11 McDonagh |
| Aircraft missed its slot because of the airline's own late boarding, crew or technical delay | No | The cause is internal (C-549/07 test) |
| Short ATC delay plus a longer delay for other reasons | Partly | Only the ATC part is deducted (C-315/15) |
| ATC disruption earlier in the day affecting the same aircraft | Depends | Direct causal link required (C-74/19) |
ATC restrictions and slots
When airspace or an airport is busier than air traffic control can safely handle – because of weather, staffing, equipment or simply demand – flights are given later departure times, often called slots. Your aircraft cannot take off before its slot, and if it misses the slot it may have to wait for a new one.
A restriction of this kind is the textbook recital 15 case. But two practical points often decide claims:
- The slot delay is often only part of the total. Under Pešková (C-315/15, ruling 4) only the delay caused by the extraordinary event is deducted. If your flight arrived 4 hours late and the ATC restriction accounted for 50 minutes, the remaining delay is still over 3 hours.
- Missing the slot is not ATC's fault. If the aircraft was ready late because of the airline's own operation, the extra wait for a new slot results from an internal event.
Air traffic controller strikes
Strikes by air traffic controllers are not part of an airline's normal activity and are outside its control, so they are usually extraordinary (C-28/20). They are common in some countries, particularly France, and often affect overflights as well as flights to and from that country. Our strike calendar and the France strike guide list announced dates.
An announced strike also raises the reasonable-measures question. Where a strike is known days ahead, the airline can be expected to plan for it – rebooking passengers, adjusting schedules – rather than leaving everyone at the gate. If you were given short notice of a cancellation that could have been planned earlier, mention it in your claim; whether the airline did enough is decided case by case. For strikes by the airline's own staff, which are treated very differently, see our strikes guide.
The NATS failure of 28 August 2023
On the August bank holiday Monday in 2023, a technical failure in the flight planning system of NATS, the UK's main air navigation service provider, led to delays and the cancellation of hundreds of UK arriving and departing flights, with disruption continuing for several days. According to the CAA, more than 700,000 passengers were affected: around 300,000 by cancellations, 95,000 by delays of more than three hours and 300,000 by shorter delays. An independent review panel published its final report on 14 November 2024 with 34 recommendations for NATS, airlines and airports, the CAA and the Government.
On compensation, the CAA's guidance to industry of 30 August 2023 said that delays and cancellations on 28 August caused by the NATS issue were likely to be extraordinary circumstances, and that delays and cancellations directly caused by the knock-on effects were also likely to be extraordinary – so passengers were unlikely to be entitled to compensation. The guidance made three further points worth knowing:
- airlines still had to offer a refund, re-routing at the earliest opportunity or re-routing at a later date, and to provide meals, refreshments and hotels;
- where airlines could not provide care or suitable replacement flights, the CAA expected them to reimburse passengers' own costs promptly;
- the CAA's view was "illustrative and for guidance only", and passengers could still claim, including through the courts, if they disagreed.
The CAA's phrase "directly caused" mirrors the Court of Justice's test for knock-on delays. A flight days later, delayed for an unrelated reason, does not inherit the NATS defence.
What the airline must prove
- The decision or event: which restriction or strike applied, issued by whom, for which time window.
- That it concerned your aircraft on that day, and how many minutes of delay it caused.
- That the rest of the delay was also unavoidable, or that what remains is under 3 hours at arrival.
- Reasonable measures: that it asked for an earlier slot where possible, used reserve time, and – for long disruption or cancellations – looked for re-routing on its own and other airlines' flights (C-74/19).
Airlines receive slot messages from the air traffic flow management system and can produce them. The Commission's guidelines say evidence the airline relies on should be included in its reply to you.
What you can do
- Ask for the reason in writing: the restriction or strike, its duration and the minutes of delay it caused to your flight.
- Check the flight history. Flight-tracking sites show when your aircraft arrived from its previous flight and when it actually left. A late incoming aircraft points to a different cause.
- Check other departures. If flights on the same route kept leaving normally, ask why yours could not.
- Add up the causes. If the ATC part is shorter than the total, claim for the rest.
- Escalate if the airline will not explain – to the national enforcement body or ADR body of the country where the incident happened for EU, EEA and Swiss flights (see where to complain and our country guides, for example Germany, Spain, France or Italy), or ADR or the CAA for UK flights – see how to claim and the case law library.
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Frequently asked questions
My flight was cancelled because of a French air traffic control strike. Can I claim compensation?
Usually not. In Airhelp v SAS (C-28/20) the Court of Justice said strikes "external to the activity of the air carrier", such as strike action by air traffic controllers, may be extraordinary circumstances. You are still entitled to a refund or re-routing and to care while you wait. Check our strike calendar for announced dates.
The airline said "ATC restrictions" but my flight was 4 hours late. Is that the whole story?
Not necessarily. Air traffic control slot delays are often shorter than the total delay. Only the part of the delay caused by the restriction is deducted (C-315/15 Pešková). If the rest – a late incoming aircraft, a crew problem – still adds up to 3 hours at arrival, you can claim. Ask the airline how long the restriction actually lasted.
Can I claim for the NATS failure on 28 August 2023?
The UK Civil Aviation Authority said on 30 August 2023 that delays and cancellations caused by the NATS issue, and those directly caused by its knock-on effects, were likely to be extraordinary circumstances, so compensation was unlikely. It added that this was guidance only and that passengers could still claim, including in court, if they disagreed. Care, refunds and re-routing were owed regardless.
What if we missed our slot because boarding was late?
Then the slot is not the real cause. If the aircraft missed its departure slot because of the airline's own delays – late crew, cleaning, catering, a technical check – the resulting extra delay is the airline's responsibility.
Is air traffic control staff shortage the same as a strike?
Both come from outside the airline. A capacity cut imposed by air traffic control on your aircraft is an air traffic management decision of the kind recital 15 describes, whatever the reason behind it. The airline must still show the restriction applied to your aircraft and that it did what it reasonably could to reduce the delay.
Do I get meals and a hotel during an ATC delay?
Yes. Care is due from 2, 3 or 4 hours of delay depending on the distance, and a hotel if you are delayed overnight – whatever the cause.
General information, not legal advice. We are an independent guide, not lawyers and not AirHelp.
Sources
- Regulation (EC) No 261/2004 – recitals 14 and 15 (as adopted) – legislation.gov.uk
- Regulation (EC) No 261/2004 – Article 5 (as adopted) – legislation.gov.uk
- Interpretative Guidelines on Regulation (EC) No 261/2004 (C/2024/5687), section 5 – European Commission, Official Journal
- C-315/15 Pešková and Peška, judgment of 4 May 2017 – Court of Justice of the EU
- C-74/19 Transportes Aéreos Portugueses, judgment of 11 June 2020 – Court of Justice of the EU
- C-28/20 Airhelp v SAS, judgment of 23 March 2021 – Court of Justice of the EU
- Guidance to industry on the NATS flight planning failure, 30 August 2023 – UK Civil Aviation Authority
- Aviation regulator publishes independent review into August 2023 NATS flight planning system failure – UK Civil Aviation Authority
- Am I entitled to compensation? – UK Civil Aviation Authority
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