Ryanair passengers could be in line to receive compensation, after more than 100,000 flights were cancelled due to strikes.
Those who were affected are being urged by the Civil Aviation Authority (CAA) to claim back their money, under European flight rules.
How much could I be entitled to?
According to a law known as EU261, compensation is set at €250 (approximately £223) for flights of up to 1,500km, and €400 (around £357) for longer flights in Europe and North Africa.
But if a flight is cancelled due to extraordinary circumstances, passengers will not necessarily be entitled to compensation under the EU regulation.
Along with other airlines, Ryanair maintain that strikes do qualify as 'extraordinary circumstances' and claim that they are therefore exempt from the EU compensation rules.
Do Ryanair have to pay up?
"Under EU261 legislation, no compensation is payable when the union is acting unreasonably and totally beyond the airline's control," Ryanair said in a statement, confirming that they would reject any claims.
But, according to the CAA, passengers are entitled to compensation in the event of strike action if they have not be warned of flight cancellations two weeks in advice.
"When a flight cancellation is caused by strike action by the airline's employees, the airline is required to pay compensation to passengers in respect of the cancellation of the flight, if it has not warned passengers of the cancellation at least two weeks prior to the scheduled time of departure," said a CAA spokesperson.
More travel chaos expected
Thirty Ryanair flights between Ireland and the UK were cancelled earlier this month, due to a 24 hour strike. Passengers are set for further disruption this week, as pilots in Dublin are due to go on strike on Tuesday (24 July).
Elsewhere, cabin crew in Europe will go on Wednesday and Thursday, bringing more travel misery for holidaymakers.
The industrial action this week is due to affect more than 50,000 customers.