Ryanair passengers whose flights have been cancelled may be entitled to compensation.
Here are some of the key questions around the claims process:
What rules apply?
EU law protects passengers whose flights are delayed or cancelled under the Denied Boarding Regulation.
This applies to flights either departing from an EU airport or those that are both arriving at an EU airport and operated by an EU airline, such as Ryanair.
Are passengers entitled to a refund?
Yes, customers can claim a refund from the airline. If they have booked a return flight and the outbound leg is cancelled, they can also claim the full cost of the return ticket.
What if a passenger still wants to travel?
Airlines must offer an alternative flight as soon as possible after the cancelled service.
The Civil Aviation Authority says passengers may have the right to be booked onto a flight by an alternative airline if it is flying there "significantly sooner" than the original airline's own alternatives.
Do passengers get any assistance while they wait?
Delayed passengers are entitled to claim reasonable expenditure for food, soft drinks, phone calls and accommodation.
What about compensation?
If less than 14 days' notice is given for a cancellation, airline travellers can claim up to 250 euros (£221) under EU Regulation 261, depending on the timing of the alternative flight.
Customers given more warning are not entitled to a payout.
Is compensation automatic?
No, disrupted passengers must write a letter of complaint to the airline. They should keep as much evidence as they can, such as boarding cards and receipts to claim expenses.
A template letter can be found on the website of consumer watchdog Which?
What if they are not satisfied with Ryanair's response?
Unhappy passengers can refer their claim to the airline's appointed dispute resolution service AviationADR, which will make independent decisions on passengers' claims that Ryanair is contractually obliged to abide by.