Revelers in northern Thailand have been asked not to launch lanterns into the sky near airports to avoid airborne accidents during a popular festival this week, airport officials said Tuesday.

The air traffic control center in Chiang Mai province has declared a 5-kilometer (3-mile) zone around the airport where people are advised not to launch lanterns from Wednesday to Friday, when Loy Krathong festival celebrations will take place, said Kiattisak Rienvatana, the center's director.

During the festival, Thais float small rafts on rivers to ask for forgiveness from the goddess of water. They also believe that launching lanterns will rid them of bad fortune.

Authorities and airlines, however, have expressed safety concerns over the lanterns.

"We are asking the people to cooperate because only one lantern can bring down a plane," Kiattisak said by phone. "Our officials are also keeping an eye on any lanterns that might be blown into the airport parameters during that period."

Revelers have been advised that they may float lanterns near the airport after 9 p.m., when the air traffic is cleared up.

Authorities in nearby Chiang Rai province have issued a similar request.

Several airlines, including Thai Airways, have adjusted their flight schedules to give way to the lantern floating, which takes place mainly after dark.