Six-year-old Daniel Immerman stood in the cockpit of the TWA jetliner, smiling broadly as the captain explained the controls and told him he would make a fine pilot one day. His mother Ray waited in the aisle, wearing her worry on an ashen face and postponing the moment when she would leave Daniel in the flight crew's care.

It was the day before Christmas, and Daniel was on his way from National Airport to New York to spend the holiday with his grandparents. Mom, Dad and little brother Michael were staying in Silver Spring.

"This is the first time he's ever gone alone," said Daniel's father Bill. "It's not too bad for me, but it was a hard decision for {his mother} to make. We'll meet him back here. By then he should be a seasoned traveler."

Daniel Immerman kept his feelings to himself as a flight attendant buckled him into the window seat in the first row of first class. The plane pulled away from the gate, and in the lull before the final holiday travel rush, Daniel took his place among a growing population of young travelers flying unaccompanied on the nation's airlines.

An estimated 500,000 children between the ages of 5 and 11 boarded planes without their parents or adult companions this year, including a surge during the holiday season, according to airline officials.

Where unchaperoned minors were once a rarity, post-deregulation fare wars and the high divorce rate have contributed to a class of young passengers who sometimes feel more at home in the sky than their parents, industry observers said.

And where children once took in the experience with a mixture of awe and wonder, many today treat air travel as little more than a means of getting from Point A to Point B or from parent to parent.

"There's not really that much to it. You just sit there," said 12-year-old John Twiss of McLean, who first flew solo when he was in third grade and prefers it to the alternative: "It's fun because you're not with your parents who are always bossing you."

Some airline officials acknowledge that a mixture of motives prompts them to pay extra special attention to fledgling fliers. It's never too early to begin building brand allegiance, they note.

Continental Airlines sends birthday cards to each member of its "Young Travelers Club" and encloses a voucher they can redeem for a T-shirt bearing the club logo, a company plane circling the globe against a cosmic backdrop.

Legions of children crossing the country during the summer vacation, visiting relatives or shuttling between parents who live in different cities account for the vast majority of young passengers, airline officials said.

Many are frequent fliers.

"There are some seasoned travelers that are 6 years old that will come on and say, 'I'd like the 7-Up please and the peanuts,' " said Sue Moss of United Airlines.

One veteran is Tara Stapleton, who flew from St. Louis, where she lives with her mother, to spend Christmas with her father, Jake Stapleton, in Fairfax County. Tara, 9, makes the round trip three times a year.

She requests an aisle seat and hopes for interesting company, her father said.

The little girl, who clutched a doll, was escorted from the gate at National Airport to the security checkpoint in a motorized cart and leaped into her father's embrace.

"The first time she cried," Stapleton recalled, but "she's been doing it for three years and she loves it. It's no big thing for her anymore." The only rule, Stapleton noted, is that Tara does not travel alone in a snowstorm.

While many parents are comfortable putting their children on planes, others harbor reservations.

A mother from Johannesburg, who was passing through National Airport last week, said she has gotten accustomed to her two boys flying by themselves in their country but could not conceive of letting them travel alone here.

"The first time it was terrible. It is an anxious moment. If something happens to the plane, you want to be there," said Jillian Graham. "I would be dead scared here. There are too many people. I'd think they'd get lost or left behind."

The airlines have developed an elaborate system to prevent such fears from being realized. Generally, children younger than 5 years old are prohibited from traveling alone, and children between 5 and 7 are not allowed to make connections. Those between 8 and 11 are escorted by airline employes from gate to gate when they transfer planes at a charge of about $20, airline officials said. Colorful badges and buttons issued by the airlines make them easy to identify in a crowd.

Unaccompanied minors are typically seated near the front of the plane, where flight attendants can give them closer attention.

When booking children's flights, parents are required to name the people who will meet them at the other end, and airline officials demand positive identification before releasing a child.

"Sometimes this can be a little strange when the child runs up the ramp and says, 'Mommy, Mommy, Mommy!' and the flight attendant says, 'May I see some identification, please?' " Continental passenger services chief Dan Morgan noted.

Occasionally, however, even the tightest safety nets fail. Continental employes still shudder at the thought of the 13-year-old girl who slipped away en route to Miami from Montreal. Panic set in as the FBI began a search.

The girl turned up safe several days later. She had run away to visit relatives in California.

Airline employes tell stories of seemingly callous or cavalier parents who drop off their children at the terminal entrance or keep them waiting hours after they arrive. But when travel goes awry, circumstances beyond any individual's control are usually to blame. A spokesman for Continental said an average of eight to 10 chidren flying with his company are stranded weekly during the summer in each of four hub cities as a result of canceled flights or missed connections.

In those instances, the airlines have one of their employes spend the night in a hotel with the child or take the young passenger home with them.

Gary Yeary, a Continental manager, remembers brightening an otherwise melancholy Christmas Eve for one wayward traveler three years ago. The 12-year-old boy from Central America was on a journey to visit his mother in Colorado when a snowstorm closed the Denver airport, stranding him in Houston.

The Yeary family took the boy home overnight, gave him a gift from under their tree, and shared their Christmas dinner before taking him to meet a rescheduled flight. The airline would have put the boy in a hotel, Yeary said, "but on Christmas Eve, that just didn't seem right."