Around 19 Ryanair customers, due to fly to Belfast from Spain, watched in disbelief from the airport gate as the plane flew off without them.
The passengers were left standing for hours at Gate 31 of Alicante airport as other passengers boarded the plane and left.
At Alicante-Elche airport the scheduled flight on Wednedays night at 9.10pm, flight FR1308 to Belfast International, flew off leaving 19 stranded.
Passengers said doors to the tarmac, where the Ryanair plane was waiting, appeared to have been locked after other passengers had been let through and boarded the plane.
One Lurgan woman said the remaining passengers tried to alert the Ryanair staff at the gate.
“They herded us back down to the Gate and totally ignored our pleas,” she said.
“One guy whose friends were already on the plane called his mate and explained the situation but nothing happened.
“We all watched in disbelief as the plane taxied down the runway and flew off without us.
“We told the staff we could see the plane going and she told us to stand back and stay where we were.”
The 50-year-old woman, who was with her husband, said they were OK as they just had hand luggage and have a home in Spain.
But she explained there was an elderly man who was diabetic and his medication was in his luggage which was on the plane.
“He looked very ill after waiting at the gate for hours with no seating,” she said.
The Lurgan woman added: “We were herded like cattle into a holding area with no seating and we pleaded with them to let us up the ramp to the seating area but were refused.”
After the plane left, she said two men and a girl arrived to apologise.
“They said nothing like this had ever happened before and that we would be compensated,” she said.
She said they were then taken through security and told to stand at a desk.
“It was horrendous,” she said. “People were concerned about getting home and that their luggage was on that flight which had just left.”
The woman claimed a member of staff said there no flights the next day - only fights on Friday with just one seat. A fact she disputed.
“My husband showed the girl 14 seats available on the Friday flightbut we were still told that the earliest we could get home was the 21st June,” she said.
“It affected people from all over Northern Ireland, Derry, Belfast everywhere.”
“It was a nightmare. We were not treated like human beings.”
A spokesperson for Ryanair said: “All customers on this flight have been provided with hotel accommodation and alternative flights have been organised.”