Check compensationCheck

Why was my flight delayed? How to find out – and why it matters

The cause decides whether you get £220–£520 / €250–€600. How to find out why your flight was late, what evidence to collect, and what the airline must prove.

By the EU261 Flight Delay editorial team Last reviewed: Reading time: 7 min How we write our guides

Check compensation or start a claim with AirHelp straight away

In short: whether you get compensation for a delay of 3 hours or more depends on its cause. If it was within the airline’s control – a technical fault, a crew shortage, the airline’s own staff striking – you are usually owed £220–£520 (UK261) or €250–€600 (EU261). If the airline proves extraordinary circumstances such as severe weather or an air traffic control strike, it is not. The burden of proof is on the airline, but you will get further if you collect your own evidence on the day: announcements, messages, times, and what happened to other flights.

“Why is my flight delayed?” is one of the most searched flight-delay questions in the UK. Here is how to find out, and how to use the answer.

Why the cause matters

Typically within the airline’s control (compensation usually due) Often extraordinary (compensation usually not due)
Technical problems, including those found during maintenance Weather incompatible with safe operation
Crew shortages, a sick pilot not replaced, crew arriving late Air traffic management decisions and ATC strikes
Strikes by the airline’s own staff Strikes by airport, ground-handling or border staff
Overbooking Security risks, political or civil unrest
Mobile boarding stairs colliding with the aircraft Hidden manufacturing defects (e.g. a recall grounding a fleet)

This summarises examples given by the UK Civil Aviation Authority, Your Europe, Citizens Advice and MoneySavingExpert; each cause has nuances, explained in our extraordinary circumstances guide and its sub-pages on bad weather, air traffic control, strikes, technical faults, crew shortages and knock-on delays.

Note that the cause matters only for compensation. Meals, hotel and re-routing are owed whatever the cause.

What the airline has to prove

Under Article 5(3) of Regulation 261/2004 – and, for delays under UK261, Article 6(4) – an airline that wants to avoid paying compensation must prove two things:

  1. the delay or cancellation was caused by extraordinary circumstances; and
  2. it could not have been avoided even if all reasonable measures had been taken.

So it is not enough for the airline to say “weather”. It has to show that weather affected your flight and that it could not reasonably have avoided or shortened the delay. For EU261 flights from 23 October 2027, Regulation (EU) 2026/2202 requires an airline rejecting a claim on these grounds to name the extraordinary circumstance it relies on (from the list in the new Annex, or explain why an unlisted event qualifies) and give a clear, substantiated explanation of the causal link and the reasonable measures taken (amended Articles 6c and 7(9)). The reform does not apply to UK261.

What the airline must tell you on the day

Article 14 requires airlines to display a notice at check-in about passenger rights and, when a flight is delayed by at least two hours, to give each affected passenger a written notice setting out the rules for compensation and assistance, plus the contact details of the national enforcement body. The regulation does not oblige the airline to give a detailed technical reason in that notice – which is why your own notes matter.

Evidence you can collect at the airport

  • Announcements. Note what the gate staff and the captain say, and when. “We’re waiting for a replacement crew” and “we have a technical issue with the aircraft” are very different from “air traffic control has given us a slot”.
  • Messages. Screenshot every text, e-mail and app notification, including the time it arrived.
  • The departure board. Photograph it, especially if only your flight is delayed while others to the same destination depart.
  • The aircraft. Was your plane at the gate? If it arrived late from an earlier flight, note the inbound flight number if staff mention it.
  • Other passengers’ information. Write down what others were told – airlines sometimes give different explanations to different people.
  • Arrival time. Note when the doors opened at your destination. The Court of Justice ruled in Germanwings v Henning (C-452/13) that this, not touchdown, is the arrival time.

Evidence you can check afterwards

  • Flight-tracking websites and apps show the scheduled and actual departure and arrival times and often the aircraft’s previous flights – useful to see whether the delay began earlier in the day.
  • Other flights from the same airport at the same time: if many airlines operated normally, a weather or ATC explanation is weaker.
  • Strike notices: our strike calendar lists announced strikes by country, including France and Spain.
  • News reports of airport closures or air traffic restrictions on that day.

Ask the airline in writing

If the airline’s reason is vague, ask it in writing – in your claim or after a rejection – to state:

  1. the specific event that caused the delay, with time and place;
  2. how that event affected your flight (for example, which earlier flight of the same aircraft was delayed, and why);
  3. what it did to avoid or reduce the delay, such as using a spare aircraft or crew, or re-routing you.

Our complaint letter generator includes these questions. If the airline sticks to a reason you think is wrong, the escalation route is in claim rejected – what next.

Common explanations, decoded

“Operational reasons.” Not a legal category. Usually means something within the airline’s control – ask for detail.

“Knock-on delay from an earlier flight.” The airline may rely on an extraordinary event that affected an earlier flight of the same aircraft only where it is directly linked to your delay and it took reasonable measures; an ordinary earlier technical problem or crew issue does not become extraordinary because it happened earlier in the day. See knock-on delays.

“ATC restrictions.” Air traffic control decisions can be extraordinary, but the airline must show they actually caused your delay. See air traffic control delays.

“Technical problem.” Usually not extraordinary. The CAA cites Jet2 v Huzar (English Court of Appeal, 2014) and van der Lans v KLM (CJEU, 2015). See technical fault delays.

“Crew sickness / staff shortage.” Generally within the airline’s control. See staff shortage delays.

“Bad weather.” Can be extraordinary, but not automatically – see bad weather delays.

Next step

Once you know – or suspect – the cause, run your flight through our checker. If it looks like an airline-controlled cause and you arrived 3 hours or more late, claim from the operating airline using our step-by-step guide. Leading court rulings are collected in our case law library.

Sources

More articles