Around 50 third-level students were among the passengers stranded in Poland after a Ryanair flight from Krakow to Dublin was delayed and then re-routed on Friday.
The group were final year UCD Science students, on their last group trip before finishing university.
Eyewitnesses said some of the original flight's passengers remained in the Polish airport this morning.
Flight FR1902 was due to take off at 3.35pm on Friday but was delayed because of fog.
After an initial delay, passengers were informed that their flight would take off from Katowice Airport, around 100km away, and that a bus would take them to the airport.
However, many passengers took to social media to complain that the bus never came and they were left stranded at the airport.
Cat Sawkins was one of the passengers caught up in the episode. Ms Sawkins lives in Bray and was returning from a snowboarding holiday.
Ms Sawkins told RTÉ News that passengers were waiting outside in the cold for two hours looking for the bus. "We were going up and knocking on bus doors and asking 'are you for the Dublin flight?', and they all said no."
Ms Sawkins said passengers were then instructed to return inside. Two more announcements instructing them to go outside for a bus followed, she said, but each time there was no bus for them.
At around 9pm the passengers realised they would not make their flight, Ms Sawkins explained.
When a member of staff did speak to them about what had happened, Ms Sawkins said the passengers were told: "You missed your flight because you missed your bus".
Despite passenger claims to the contrary, Ryanair issued a statement to say that "coaches were organised".
It said that the flight had been delayed due to heavy fog and that passengers had been notified of the delay and had been advised of refund or re-route options.
"Ryanair sincerely apologised to all customers affected by this weather delay, which was entirely beyond our control," it said.
Ms Sawkins said that she understood that 10 people travelled on the Katowice flight that left on Friday night, and she believed they had all made their own way to the airport.
A Ryanair spokesperson said the airline could not provide figures on how many made that flight.
Twenty-two-year-old Laura Murphy was among the students due to travel on flight FR1902 on Friday.
She said they were treated "abysmally".
Ms Murphy said many of the students were very concerned about how they would afford the cost of getting home, with some spending up to €400 on new flights.
She said that she knew of at least one person who had to borrow money from a friend.
Ms Murphy and a group of friends made their own arrangements to get home and arrived back in Dublin last night.
She said she understands that others were still making their way home today.
@Ryanair Due to fly from Krakow-Dublin on flight FR1902 15:35 17/1/19. The flight was delayed, moved to Katowice airport and Passengers were advised to board buses outside the airport to Katowice..THESE BUSES NEVER CAME. There are over 100 people stranded! @SkyNews @LeoVaradkar pic.twitter.com/OpVd9mXP6A— Neil_Brown (@NeilBro50674768) January 18, 2020
Twenty-nine-year-old Neil Brown from Belfast and his girlfriend Niamhemma Quinn were also due to fly on flight FR1902.
Speaking to RTÉ News, Mr Brown described their treatment in the airport as "inhumane nearly".
The airline said it had provided passengers with refreshment vouchers, however passengers say these were offered after 2am when few options to use them were available.
Both Ms Sawkins and Mr Brown say they were among around 100 passengers who were left in Krakow airport on Friday night, and that the group included a large number of students.
Mr Brown said he spoke to a student who said that all he had brought with him was enough spending money for the trip and he was "completely and utterly stranded".
A Ryanair spokesperson told RTÉ News that " all customers that didn't take the flight from Katowice have been re-booked on alternative flights or refunded".
Ms Sawkins said that there were still fellow flight passengers in Krakow airport when she arrived there to get a flight from there this morning.
She said that one student she met had to ask a friend to pay for her flights home.
Ms Sawkins travelled via Brussels to Dublin today on flights re-booked by the airline.