Up to 9,000 passengers remained stranded across 12 cities in Europe yesterday after Aer Lingus cancelled scores of flights following a major IT issue.
Thousands of people were seen queuing outside Terminal 2 at Dublin Airport on Saturday morning, when it was first reported that digital systems had failed.
Aer Lingus has apologised to customers after it cancelled 51 flights to and from the capital's airport over the weekend but say its systems have now been restored.
The airline added that customers affected by the disruption will be able to change their travel plans free of charge.
Speaking yesterday, travel industry expert Eoghan Corry said: "There's around 9,000 people swept up in it all. We've got people stranded in 12 different cities throughout Europe, and most of them are having to make their own way home. It could take several days to get all of those people home."
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Mr Corry added that the destinations in which people are stranded include Rome, Lanzarote, Bulgaria, Berlin, Geneva, Turkey and Venice.
"They are refunding people but the big problem is that they're being very, very poor at communicating this. People have got no information or they've got conflicting information.
"People even came home from the airport yesterday to find that their flights had taken off despite the fact they were told their flight was cancelled. If you are in a distant airport, there aren't any Aer Lingus staff to communicate with you," he said.
One couple from Dublin said they were left stuck at the airport for almost ten hours on Saturday, when their flight to Toulouse, France, was seriously delayed. Ciara, 29, said: "It was just terrible. The whole weekend has basically been ruined.
"We arrived at Dublin Airport at 9.15 on Saturday morning, and our flight wasn't due to take off until 11.35.
"At that stage, the queues had started to form outside, and we were told there was an IT issue. I thought it would be resolved within 15 minutes, but we were left standing outside the terminal at the airport for five and a half hours. The experience was miserable - it was really cold, and there were two old ladies travelling to America behind us.
"When we finally got water at about 1pm, one bottle each, the old lady couldn't even open the bottle. It was just so bad for her - I'd say she was around 80."
Meanwhile, Lisa Webb, from consumer magazine Which? said: "Aer Lingus's sudden cancellations of flights to and from the UK and Europe will cause thousands of passengers distress and anxiety when it comes to their travel plans.
"Aer Lingus must give clear information to affected customers about their entitlement to compensation."
A spokesman for the airline said: "Aer Lingus sincerely apologises to customers for the severe disruption caused today by the unavailability of key systems."
