A flight attendant was injured and some passengers were frightened when, officials said, a mid-air Allegiant flight had to “initiate a climb” to avoid colliding with another plane.

The incident happened Sunday afternoon on Flight 485, which departed from Fort Lauderdale-Hollywood International Airport at 12:44 p.m. bound for Blue Grass Airport in Lexington.

At one point during the flight, the Allegiant plane, an Airbus A320, was at the same altitude as another aircraft and had to take “evasive action,” according to the Federal Aviation Administration. An air traffic controller in the Miami Air Route Traffic Control Center told Flight 485 “to turn eastbound at an altitude of 23,000 feet when it crossed in front of a northbound Gulfstream business jet,” according to the spokesman.

The pilot of the Gulfstream also had to take “evasive action after receiving a similar alert,” according to the FAA spokesperson.

Allegiant spokeswoman Sonya Padgett added, “the pilots had to initiate a climb” after receiving the automated alert about a nearby aircraft. There were 175 passengers and six crew members on board the Allegiant plane.

Jerrica Thacker, 21, was traveling back home to Kentucky with family after finishing up a six-day cruise to the Bahamas, Mexico and Grand Cayman which docked at Port Everglades.

She said passengers were taken aback when the plane abruptly and sharply “went up in the air. It was probably one of the most terrifying things I experienced.”

Passengers onboard were crying, Thacker said, after the “pilot came on the intercom and told us we had turned around (after an) abrupt maneuver to miss another aircraft.”

Allegiant’s spokeswoman said during the movement, a flight attendant lost her balance, fell, and was injured. That was the reason for returning to Fort Lauderdale so she could be treated by paramedics. Padgett said there were no other injuries.

The spokesperson for the FAA did not comment on how the planes got so close, or if anyone was to blame, saying that the incident is under investigation.

The spokesperson did not provide details about the private jet, including how many people were on board or where it had been departing and arriving.

How this incident happened is still unknown.

“Human error is always going to be there,” said Mike Boyd, of BoydGroup International Inc., a Colorado-based aviation consulting company.

Air traffic control is tasked with helping keep flights safe, he said. Though it’s yet to be determined what role, if any, air traffic control had in Sunday’s incident, “airplanes follow the directions of air traffic control,” Boyd said.

Allegiant’s spokeswoman said the flight was delayed because the injured flight attendant needed to be replaced. The flight left at 7:04 p.m., arriving in Lexington at 9:19 p.m.

“We’re very sorry for the inconvenience this caused our passengers,” Padgett said. She said passengers received meal vouchers to use while they waited, as well as $100 vouchers that can be used for future travel.

Thacker said the airlines refunded their cost of the flight because her family was “too terrified to step back on the plane.”

She was traveling with her aunt, sister and her sister’s boyfriend. So they spent $800 for a last-minute car rental, drove 14½ hours to the Lexington airport to return the car, and then spent another two hours driving to their house in Pikeville after her sister’s boyfriend’s stepdad picked them up.

She guesses they were only in the air about a half-hour when the incident happened.

“I’ve been having nightmares about it,” she said Wednesday.

Lisa J. Huriash can be reached at . Follow on Twitter @LisaHuriash