What happens if a flight is delayed?

An airliner rarely flies just one leg a day: it strings together rotations. When one is delayed, the airline's operations control center assesses whether the slip is absorbed by the scheduled buffer between flights or spreads to the next ones. That triggers chain decisions: shortening turnaround time, swapping the assigned tail number, reassigning crews who are about to run out of maximum duty time, or, in the worst case, cancelling a rotation to save the rest of the day.

On top of that comes airspace management. If the cause is congestion or weather, air traffic flow control assigns the flight a departure window, or slot, and the aircraft can't leave before it even if it's ready. Losing that slot because one passenger doesn't show up at the gate can cost another hour of waiting.

On flights covered by EU Regulation (EC) 261/2004 — departures from the European Union or arrivals into it on a European airline — assistance is mandatory and doesn't depend on the cause: food and drink while waiting, communication, and, if the delay forces an overnight stay, accommodation and transport. The threshold is two hours for short flights, three for medium-haul and four for routes over 3,500 km.

Financial compensation is a different matter. It kicks in when the passenger reaches their final destination three hours or more late and the airline can't prove an extraordinary circumstance, such as a severe storm or an airport closure. A routine technical fault doesn't count as one.

The boarding pass, expense receipts and any communication from the airline form the basis for a later claim. It's also worth noting the actual door-opening time at the destination, which is the figure that legally determines the delay.