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The mother and son were due to fly with Allegiant in July from Chattanooga, Tennessee, to Florida's Tampa Bay Area, the complaint said. It added that after telling a gate agent about her son's nut allergy, Shelton was told cashews would be served on the flight.

Shelton said that upon boarding, she informed a flight attendant about her son's allergies, and they agreed not to serve cashews.

However, the complaint added that another flight attendant overheard this and "became visibly enraged."

Shelton's complaint said the flight attendant told the gate agent, "I'm going to get them off this flight."

It added that the crew member said Allegiant pays commission for snack sales, so they wanted the family deplaned to earn a commission on nuts.

The gate agent boarded the plane once before Shelton confirmed she and her son weren't being unruly, but then he returned and informed them they were being removed from the flight, per the complaint.

Shelton said she asked how they were being unruly, and the gate agent responded that a food allergy could cause an emergency landing.

However, the complaint added that in a recorded conversation, the gate agent then said the crew "invented" the claim of them being unruly.

With no alternative Allegiant flight from Chattanooga for another two days, Shelton said she hired a car and drove through the night to take a flight from Atlanta the next day. Allegiant only issued a refund in flight credits, the complaint said.

It asks the DoT to mandate training for Allegiant crew about allergies and for the airline to pay a fine and damages.

Allegiant declined to comment when contacted by Business Insider, citing company policy not to comment on pending litigation.