(1)References in this Part to a public airport company are references to a company (whether formed under section 13 or not) which carries on the business of operating an airport as a commercial undertaking and is for the time being either—
(a)a subsidiary of a single principal council, or
(b)a subsidiary of two or more such councils.
(2)In this Part of this Act—
(a)references to the controlling authority of a public airport company are references to the principal council or principal councils of whom it is for the time being a subsidiary as mentioned in subsection (1); and
(b)references to a composite authority are references to a controlling authority consisting of two or more principal councils, the councils concerned being referred to as the constituent councils of that authority.
(3)For the purposes of this Part a public airport company is an associated company of a principal council if that council are its controlling authority or one of the constituent councils of a composite authority who are its controlling authority.