Mystery Tours Go There and Back Again : Travel: KLM provides discount tickets to those who just want to fly for the fun of it. They don’t know where they’re going ahead of time, and aren’t permitted to leave the airport once they get there.

Some people on this plane don’t care where it’s going.

It is heading for Stockholm, but they would be just as happy going to Lisbon, Larnaca or Liverpool.

Take Remco Rijkhals and Steven Peeters. They planned this journey weeks ago, but when they booked their tickets they had no idea where they would end up.

“I’m just addicted to flying,” said Rijkhals, 19. “I think it’s great. The food is one of the high points. And I love airports. I’m just crazy about all of it.”

Rijkhals is one of thousands of Dutch adventurers of all ages who embark every year on daylong European flying mystery tours offered by KLM-Royal Dutch Airlines.

Exciting as the tours may sound, there is a catch.

When the touring passengers arrive at their destination, they are not allowed to leave the airport; they must return on the same plane that brought them. Rijkhals and Peeters will have all of 20 minutes in Stockholm.

KLM thought of the scheme as a way of filling empty seats and cutting losses on scheduled flights. For European airlines grappling with excess capacity, every empty seat is a loss, and carriers are going all out to win passengers.

“Naturally, our starting point was that we had seats which weren’t being used,” said KLM spokesman Peter Wellhuener. “But we also wanted to give the consumer a chance to get to know our product at a bargain price.”

At $80 per adult or $45 for travelers under 18, the tickets cost about one-10th of the cheapest published adult return on KLM’s scheduled Stockholm service. Each tour costs the same wherever it goes.

The restrictions have not discouraged the Dutch. KLM says 5,000 to 6,000 passengers take off on mystery tours each year. By May, numbers had risen by 25% from 1992.

It may be anathema to globe-trotting executives, but for enthusiasts, spending the day flying in a jet aircraft is the object of the exercise.

“I saw houses and clouds,” said 7-year-old Jacqueline van Kruisteren after the first leg of a birthday-treat flight. “I wasn’t scared. I liked it. But my ears hurt.”

As the mystery tour passengers piled into tax-free shops at Stockholm’s Arlanda airport to buy souvenirs, Jacqueline’s grandfather, Cornelis Donken, said he has promised her 4-year-old brother the same treat when he is old enough.

“It’s about flying for flying’s sake, or traveling for traveling’s sake,” Wellhuener said. “You could say it’s like plane-spotting, with the added extra of getting on the plane.”

Rijkhals has been to Paris and Manchester on the scheme. He and Peeters hope to visit every European airport eventually.

Wellhuener said one “mystery tourist” clocked up so many trips in a year that he earned a free scheduled flight under KLM’s frequent-flyer program.

KLM and the British-based International Airline Passengers’ Assn. (IAPA) believe no other airline has developed a program similar to the one that KLM has been offering for five years.

“I’ve never heard of any such thing in my life,” said Roland Baird, IAPA chief executive. “It’s an excellent idea, because it’s giving people the opportunity of flying but at the same time giving benefits to the company.”

Wellhuener said the ticket price usually covers most of the variable costs of the program, though the point at which any airline breaks even varies from flight to flight and depends on how many high-paying business-class travelers are on board.