Airports of Thailand Plc is continuing with plans to impose an additional 35-baht security fee on passengers using its facilities starting Dec 1 The AoT board agreed Tuesday to keep the plan unchanged for passengers on international routes, as well as transit and transfer flyers at Suvarnabhumi, Don Mueang, Phuket, Chiang Mai, Hat Yai and Mae Fah Luang in Chiang Rai.