EU261, explained plainly

What it covers

EU Regulation 261/2004 sets compensation for passengers facing denied boarding, flight cancellation, or long delays — on flights departing an EU/EEA airport (any airline), or arriving in the EU/EEA on an EU-based airline.

The 3-hour rule

Delay compensation only kicks in at 3+ hours late at your final destination — not departure delay. A flight that leaves 4 hours late but makes up time and lands only 2 hours late doesn't qualify. This is based on the Sturgeon ruling by the Court of Justice of the EU (2009), which extended delay compensation to match cancellation compensation.

"Extraordinary circumstances" — the part airlines dispute most

Airlines don't owe compensation if the disruption was caused by something outside their control: severe weather, air traffic control strikes (when not the airline's own staff), security threats, or political instability. They generally do owe compensation for technical/mechanical faults, crew shortages, and most strikes by their own staff — even though airlines sometimes dispute this.

What it doesn't cover

EU261 doesn't apply to delays under 3 hours, cancellations with 14+ days' notice, or flights entirely outside EU jurisdiction (e.g. a US domestic flight). It also doesn't cover indirect costs like a missed hotel booking — only the fixed compensation amount and, separately, "duty of care" provisions (meals, hotel, communication) during the disruption itself.