(CNN) -- Two California parents say their 16-year-old son was stopped from getting on an American Airlines flight because he has Down syndrome.
Joan and Robert Vanderhorst say the boy, Bede, was set to fly with them from Newark, New Jersey, to Los Angeles on Sunday when the pilot told them the boy could not fly.
"We were not allowed on the plane because this man saw my son and made a decision," Joan Vanderhorst told CNN affiliate KTLA. "This little boy had a seat in first class and for some reason that wasn't acceptable."
"The young man was agitated and running around the gate area prior to boarding," American Airlines spokesman Matt Miller said in a written statement. "Our pilot noticed and asked a customer service manager to talk to the family to see if we could help him calm down and get better acclimated to the situation. That effort was ultimately unsuccessful."
The Vanderhorst family says Bede was well-behaved, and they showed video of him sitting in the gate area playing with his hat.
"He's behaving. He's demonstrating he's not a problem," his father is heard saying on the video.
Bede has flown with his parents dozens of times, they said, and the only difference on this trip was they had paid to upgrade to first class.
The airline said that out of concern for Bede's safety and the safety of other passengers, it decided the family would have to take a later flight.
Under the federal Air Carrier Access Act, which requires airlines make accommodations for people with disabilities, airlines can refuse to fly a passenger who might pose a safety threat to the plane or other passengers, but they cannot make generalizations about disabilities or prevent someone from flying simply because of a disability.
"I kept saying, 'Is this only because he has Down syndrome?'" Joan Vanderhorst told KTLA.
The family ended up flying home on a different airline and American says it refunded the money the family paid to sit in first class.
The Vanderhorsts told KTLA they had not received the refund and planned to file a discrimination lawsuit against the airline.