The father said government officials questioned him, but he was as perplexed as they were.
"My son's profession in the military required he live a squeaky clean life," Richard Stansberry said.
The father said his son served four years in the Air Force before leaving last year for a job in the private sector. He wouldn't identify his son's employer, but said the firm does work for the Air Force.
There were 235 passengers and 13 crew aboard Delta Air Lines Flight 273. The flight landed safely just after 3:30 p.m. at Bangor International Airport.
According to U.S. officials who spoke to the AP on condition of anonymity to discuss personnel matters and because the investigation was ongoing, the detained man was a former member of the active duty Air Force until last year. The officials would not say what rank he held or the type of discharge he received. The man claimed he had a fake passport, but the passport was authentic, they said.
Federal officials met the aircraft at the airport. The Transportation Security Administration said the passenger was being interviewed by law enforcement.
After the man was apprehended, flight attendants collected passengers' pillows and blankets, piling the cushions in the back of the plane, according to Charde Houston, an all-star forward for the WNBA's Minnesota Lynx who was on the flight.
"It was definitely surreal, something you only hear about," Houston, who was on her way to San Diego to surprise her mother before reporting to training camp, told the AP in a telephone interview.
It was not immediately clear what the significance was of the pillows being taken from passengers.
After the failed attack aboard a Detroit-bound flight on Christmas Day, for a period of time there were extra pat-downs before boarding flights, no getting up for the last hour of the flight and some passengers reported being told they couldn't have items in their laps, including laptops and pillows.
Houston, 24, said that when Tuesday's flight landed, FBI agents boarded and helped remove the suspect, who was wearing handcuffs.
"He looked extremely calm, like a blank face. No emotion," Houston said of the man who was removed.
Richard Stansberry, of Apollo Beach, Fla., said he has not yet been able to speak to his son.
"Unfortunately, I don't think they'd let him call me," the elder Stansberry said. "In a situation like this, the government is doing what it is supposed to do."
NORAD, the North American Aerospace Defense Command, did not launch any military fighters in response to the flight, spokesman John Cornelio said. "By the time we were brought into the equation," the passenger was already under the control of air marshals, Cornelio said from Colorado.
All passengers were taken off the plane because it was an international flight and they needed to clear customs, said Rebecca Hupp, airport director.
Delta originally said the Airbus A330 would continue to Atlanta, but an announcement over the airport loudspeakers at 6:30 p.m.
alerted passengers that they'd be spending the night in Bangor. The airline was arranging for transportation and lodging at a local hotel.
The Bangor airport is accustomed to dealing with diverted flights.
It's the first large U.S. airport for incoming European flights, and it's the last U.S. airport for outgoing flights, with uncluttered skies and one of the longest runways on the East Coast.
Aircraft use the airport when there are mechanical problems, medical emergencies or unruly passengers.
Delta, based in Atlanta, is the world's largest airline and has a joint venture with Air France-KLM on flights across the Atlantic.