An airport official said, "Every time a celebrity comes and goes at the airport, some extreme fans buy a plane ticket and follow them to the boarding gate." The airport believes that about 70 people bought plane tickets and followed Wanna One to the boarding gate.

The scenes continued even in the departure lounge after they passed security clearance because some groupies had already gone through security well before the band did and were waiting at the boarding gate.

When the members came out of the van, the fans started screaming and a blizzard of camera flashes went off. Some even had portable ladders and expensive telephoto lenses.

Over 200 fans gathered in the departure drop-off area of Terminal 1 at Incheon International Airport on Monday morning to see boy band Wanna One leave for a fan event in Bangkok, Thailand.

In Singapore it is an arrestable offense to enter the departure area with no intention to travel even if in possession of a valid ticket, but Korea has no such laws yet.

The airport says 12,843 people have passed the security area but ended up not boarding their plane from January to September. Some 13 percent or 1,599 canceled their departure voluntarily.

"It is rare for people to go all the way to the boarding gate and cancel their schedule, and most of the people who do are fans of certain celebrities who bought plane tickets just to get to the boarding gate," said an aviation industry insider.

They tend to buy expensive business class or first class tickets because they offer the greatest flexibility in the event of cancellation. Some airlines charge no penalty at all when business or first class tickets are canceled on the day of purchase.

Besides being a nuisance to the stars, the practice creates inconvenience for many others who really do need to travel, either because the flight is sold out or because they have a longer wait and have to endure the hysteria.

"There is risk of accidents and we get many complaints about the havoc created by some obsessive fans," said an airport staffer.

