By Bob Sullivan

You know about airline change fees, baggage fees, premium seat fees and food fees. But how about a "you-get-to-sit-with-your-child" fee?

John Parish is giving his 5-year-old daughter the birthday present every child dreams of: a trip to Disney World. But he's afraid American Airlines has booked a travel nightmare for his family and other fliers. There's only one way out of the nightmare, he was told: Pay an additional fee, months after booking the trip.

Parish bought his tickets months ago, in March, and scored three seats together on a flight from Dallas to Orlando, Fla., for his wife, Amanda, and daughter, Megan. Then, in July, bad news arrived. American Airlines had changed the flight schedule for the return trip, and it had changed the plane, too. It was a bigger plane, but no longer could the family sit together. In fact, Megan had been moved onto the other side of the plane, rows away.

Parish, himself a frequent business traveler and American customer, thought that it was a simple mistake and that a quick phone call could correct the problem. After all, who wants a 5-year-old separated from her parents on a three-hour flight? Parish was only half-right.

There were three seats together, an American customer service agent told him. But the only way he could get them was to pay $60 in extra fees for what was now considered premium seating. Parish was outraged. But a discussion with a supervisor got him nowhere.

"What bothers me about this situation is that they are trying to charge me for something I already had paid for because they changed flight schedules," he said. "I know it's only $60, but this is a little extreme. ... It's not fair when it is literally their fault because they are changing their schedule, but they put the onus of the cost and change on the consumer."

Amanda Parish said the family had booked the trip a full seven months in advance specifically to ensure that they'd all be able to sit together.

"As a mother, I couldn't imagine letting my child fly next to a stranger," she said. "It really does feel like a bait-and-switch. At the very minimum, you should get what you paid for. ... We already paid for seats together. The point of going on vacation is to actually be together."

John Parish sent a letter to customer service asking for a response and an explanation; he got neither. Then he contacted NBC News.

American Airlines spokeswoman Mary Frances Fagan told NBC that she was "sorry that the Parish family encountered difficulties" but that a change in aircraft type can alter seat assignments.

"When aircraft changes occur, the computer tries to re-accommodate our passengers in the same seats — or close by — to those they held before the swap," she said. "In this case, one of the seats needed to keep all three members of the family together was not automatically available."

She said families that are separated in situations like this should talk to gate agents and flight attendants, who "work closely with passengers who want — or need — to fit together."

Consumer advocate and travel expert Chris Elliot says complaints about children being separated from parents are increasingly common as airlines have gotten better about flying near-full aircraft and as they increasingly turn to premium tiers and other fees for seating arrangements. Usually, however, flight attendants work with passengers to make sure kids aren't flying alone.

"The last thing anyone wants is a child separated from their parent for a nine-hour flight," said Elliot, the parent of three small children. "No one wants to be seated next to someone else's 2-year-old."

Generally, a combination of airline employee cajoling and passenger volunteers straightens out the mess, he said.

But the crush of new airline fees — including fees to guarantee seat assignments — has created an added layer of frustration to the parent-child separation drama.

"There's a perception that airlines are holding parents hostage. They're saying: 'If you don't pay the fee, we can't guarantee you'll be seated with your kids. So shell out the extra $60," Elliot said.

Elliot recommends that parents not pay the fee and demand seats together when they arrive at the gate. Passengers have to put up a fight on such issues, he said.

"In essence, the airlines are playing a game of chicken with passengers, and I would not blink first," he said. "I wouldn't pay the $60. I would show up at the airport early and say, 'Look, we've got a family of three, and we want to sit together,' and see what happens." Nearly always, parents get their way, he said.

In July, Citizens for Responsibility and Ethics in Washington became the latest group to ask federal regulators to step in and forbid airlines from separating children and parents on planes. Rep. Jerrold Nadler (D-N.Y.), also in July, introduced the “Families Flying Together Act of 2012.” Elliot thinks the sentiment is good, but he warns that the issue isn't as simple as it sounds.

"I'm concerned when the government starts to regulate things like this and thus have to define what a family is," he said. "What about couples who aren't married, for example? Would they have right to demand to sit together as families?"

The solution to the problem of ever-more-creative fees, Elliot said, is a more comprehensive determination of what consumers get for their ticket purchase.

"The Department of Transportation is going to have to step in and define what an airline ticket is and what it is not," he said. "Soon, they may charge for the ability to use a restroom. Is the emergency oxygen not included in the price? It's time to say enough is enough."

Parish said that, if he had to, he planned to trade seats with his daughter so she could fly next to Mom during the flight home. It's an obvious, if not optimal, solution.

"That will be all right, but it's the principle that bothers us," he said. "I enjoy sitting next to my wife when I fly. We're on vacation. There is value to sitting next to your spouse or significant other."

Despite the seat shenanigans, his daughter is still excited about the upcoming trip.

"She's been going nuts about it. Her grandparents just threw her a Disney-themed birthday party," Parish said.

Hopefully, they'll enjoy the trip home, too. After NBC's call to American Airlines, Fagan said that she had called a ticketing expert and had placed the three together again, free of charge.

Asked what advice she’d give to other passengers in the Parishes' situation, Fagan said this:

“I'd tell people who want — or need — to sit together to talk with the agents at the counter when they get to the airport and when they get to the gate.  As you know, some seats — including bulkhead and exit row seats — aren't given out until prior to departure and agents have some flexibility to make seating changes to accommodate passenger desires. Flight attendants also are helpful in seating people together if they are aware that families need to sit together."

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