A Borough Park couple is accusing Spirit Airlines of turning a trip to Florida into an anti-Semitic “nightmare” from start to finish — calling them “retarded” as the plane took off, harassing them throughout the flight, and having cops escort them off the plane after landing.

Chana and Yisroel Beck arrived at Newark Airport on Tuesday along with their 6-week-old, 2-year-old and 3-year-old daughters, eager to embark on their weeklong trip to Fort Lauderdale.

“It was our first family trip, a nice, beautiful vacation that turned into a traumatic experience — a nightmare from the way we were treated and how we were escorted off without being told what we did wrong,” Chana, 25, told The Post on Thursday.

She said a gate agent allowed them to take their FAA-approved Doona baby carriage onto the aircraft, but that things took a wrong turn when two flight attendants at the plane entrance saw it.

“One of them said, ‘There is no way this is coming on. I don’t care who approved it at the gate. I’m the boss here and I’m going to decide if it comes on or not,’” Chana said about a flight attendant.

She said she and Yisroel, 28, complied and folded the carriage, which they initially were allowed to take to their seats because it can convert into a car seat.

A crew member then said, “’I’m not going to discuss this — this seat is going off the plane now,’” Chana said.

A fellow flier who witnessed the tumult said he overheard a steward utter “those retarded Jews” in conversation with a female flight attendant before the plane took off.

“It was clearly anti-Semitism, a personal thing,” said the 24-year-old passenger, who identified himself only as Binyamin, of Rockland County. He said he was so shocked by the repugnant comment that he came forward to tell the couple he was prepared to vouch for them.

Once the plane was airborne and the seat belt sign was turned off, Yisroel moved to his wife’s three-seat row and took their 2-year-old on his lap.

A male flight attendant ordered him back to his seat, saying regulations did not allow five people to be seated in a single row — adding that there weren’t enough oxygen masks in the event of an emergency.

“My husband didn’t argue and returned to his seat,” Chana said. “The steward, who is called Jose, told my husband ‘shut up’ when he asked him for his last name. He said, ‘You’re going to have law enforcement meeting you when the plane lands.’”

Once the plane landed, an announcement was made for all the passengers to remain seated as two police officers and two Spirit supervisors came aboard to escort the family off without explanation, she said.

“We had no idea what was happening and why they were escorting us off. We had no idea why they were making a big deal,” Chana said. “The supervisors said the (attendants) had notes on us, that we weren’t listening and that ‘just like you want us to believe your story, we have to believe what they wrote about you.’”

Adding insult to injury, Chana said, the airline supervisors said their return tickets for Jan. 15 would not be honored and that the family is no longer welcome on any Spirit flights.

Former Assemblyman Dov Hikind, whom the family contacted about the incident, called the alleged anti-Semitic remark “inexcusable.”

“This family was traumatized, and their family vacation ruined by the unprofessional behavior of the airline staff,” he said in a statement. “The comment about ‘retarded Jews’ qualifies the steward for dismissal. Spirit has much explaining to do.”

Chana also called for the crew member to be fired, and wants Spirit to reimburse their ticket costs and compensate them for their traumatic experience.

“It was pure anti-Semitism for literally nothing,” she said.

Spirit spokesman Derek Dombrowski said the Becks have not yet contacted the airline, but that “records indicate that this guest ignored flight and ground crew instructions multiple times, beginning with the boarding process and continuing through landing.”

He said the airline will “launch an investigation and take these matters very seriously.”

“The safety of our Guests and crew is our top priority,” he added in a statement. “Spirit Airlines does not tolerate any form of discrimination. We are extremely proud of the diversity of our team and strive to provide exceptional service to all of our Guests.”