The acquisition of any land or interest therein pursuant to this part, the planning, acquisition, establishment, construction, improvement, maintenance, equipment, and operation of airports and air navigation facilities, whether by the state separately or jointly with any political subdivision, and the exercise of any other powers granted to the department by this part are public and governmental functions, exercised for a public purpose, and are matters of public necessity. All land and other property and privileges acquired and used by or on behalf of the state pursuant to this part are acquired and used for public and governmental purposes as a matter of public necessity.