Terms used in this section and sections 15-74b and 15-74c, shall be construed as follows, unless another meaning is expressed or is clearly apparent from the language or the context: “public service company” means “public service company” as defined by section 16-1; “public airport” means any state or municipality owned airport, heliport, restricted landing area or other air navigational facility or any facility licensed by the executive director of the Connecticut Airport Authority under section 13b-46, except any privately owned airport, heliport, restricted landing area or air navigational facility unless the same has been on file with the Federal Aviation Administration for a period of at least two years and designated by it as a facility open to the public; “clear zone” means an area extending for up to one-half mile from the end of a runway on a public airport and designated by the executive director as a clear zone in accordance with regulations adopted by the executive director.