Nok Air. Another Thai airline, Nok Air is the budget airline of Thai Airways International, operating domestic services from Bangkok Don Mueang Airport. Nok Air may be a small airline (although it is now the airline that serves the highest number of domestic routes within Thailand, according to the Bangkok Post), but their fleet is memorable. The airplanes are painted in colorful feathers and a bright yellow beak nose. Fitting, since nok is the Thai word for "small bird."