As they boarded China Eastern Airlines Flight 572 to Shanghai at Daniel K. Inouye International Airport at 10 a.m. Dec. 5 with their two children, Howard and Denise Greenberg were happy and excited to be getting underway with their carefully planned vacation that would take them as far as Bali, Indonesia.

This, like every trip they took, was carefully planned to leave nothing to chance, because their 16-year-old son, Joshua, has autism and doesn’t speak. The Kihei couple said they had notified the airline of this when they booked the flight and were told “no problem.”

“He’s been flying all his life without ever an incident,” Howard Greenberg said, noting that in the past couple of years, his family had flown from Hawaii to Europe, Israel and Argentina, and for this even longer flight they had, for the first time, bought business-class tickets so that they could stretch out and sleep.

As he often did while boarding, Joshua flapped his hands in front of his face and made a light buzzing sound as he got settled in his seat, typical behavior for people with autism while making transitions from one environment to another. Joshua then fell quiet and still, listening to his music on his headphones, Greenberg said.

But as Denise and Joshua Greenberg sat next to each other in the front row of business class, a flight attendant came over and said another passenger had complained of feeling threatened by the boy. To their astonishment, the flight attendant informed them the pilot had ordered the family to deplane immediately.

“He was sitting there quietly with his earphones on,” Denise Greenberg said. “I said, ‘My son has autism, he’s not a threat to anyone.’”

Howard Greenberg called the incident “clearly discriminatory of his autism” and is considering filing a lawsuit against the airline.

“They didn’t know my role,” he said. “People on Maui call me Mr. Autism.”

Greenberg is president of the Maui Autism Center, which works with children with autism, and Autism Management Services, which provides behavioral services for government agencies. His wife is executive director of the nonprofit Maui Autism Center Foundation, whose mission is to bring autism awareness to the community at large.

“It was so ironic that this was happening to us,” he said.

Greenberg, who was sitting three rows back, said he stood up and announced the family would not leave. “I said, ‘You’re discriminating against my son for having autism.’ I told them he’s nonviolent, he doesn’t speak. Joshua has never harmed anything; he’s like a little Zen monk.’”

Greenberg said he wanted to explain to the pilot that the hand flapping was not aimed at anyone and that Joshua avoided making eye contact with strangers. His request was denied, however, and instead state airport sheriffs were summoned by the airline and asked the family to leave.

“An officer went to talk to the pilot, came back and said the pilot could kick us off for any reason, that’s the law, and that the pilot was threatening to deboard the whole plane just to get us off,” Greenberg said.

After a 2-1/2-hour delay as the sheriffs mediated between the cockpit and the Greenbergs, the flight took off with the Maui family on board and landed without incident in Shanghai.

“Joshua slept the whole flight,” Greenberg said.

But their ordeal wasn’t over. As they went to board their China Eastern Airlines connecting flight to Singapore, Greenberg said, an airline employee told them they could not get on the plane because their son was “sick.”

“He’s not sick, he has autism,” Greenberg replied, but the standoff continued until another passenger, a German businessman who worked in China and spoke the language, intervened on their behalf, and they were allowed to fly to Singapore.

The Greenbergs were so fearful of being detained in Shanghai on their return trip that they flew back from Singapore on a different airline after first seeking a refund from China Eastern, which refused their request.

In an email to Greenberg, John Su Qiu, the airlines’ Honolulu station manager, said he himself was on the same flight and witnessed no discrimination.

“I believe that the captain and all the crew were concerned about the safety of the flight, that they were concerned about whether your son, in the enclosed space, would again damage and knock on the equipment, because he had been seen to do so when he first boarded the plane.”

Greenberg replied that his son did not touch any equipment “and did not bang on his seat or bang on anything.” He said he had video to prove it.

Su Qiu said other passengers and flight attendants had seen it “and they can all testify.”

Su Qiu and other China Eastern Airlines officials did not return phone calls and emails from the Star- Advertiser seeking further information.

As an autism advocate, “I feel I’m supposed to educate the airlines and let the world know this is happening right here in America,” Greenberg said.

He also plans to file a lawsuit seeking punitive damages against China Eastern Airlines.

The worst thing, he said, is that his children were traumatized.

“Josh doesn’t talk, but he’s highly intelligent and understands everything that’s said,” Greenberg said. “He knew what happened, what everybody was saying about him.”

Normally a “truly joyous kid with a smile that lights up a room,” Joshua since the incident has had outbreaks of uncontrolled crying at night as he relives the episode, and is now getting counseling, Greenberg said.

But the experience also bonded his family closer, he added.

Describing himself as “little, a vegan, weighing 120 pounds,” Greenberg said he felt proud when he stood up on the plane to speak for his son, and his 15-year-old daughter Jazmine cried out, “You’re a superhero, Daddy!”

Most of all, he added, he wants his children to know he’s proud of them.