The acquisition of land or interests in land under this chapter, 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 person or municipality, and the exercise of any other powers granted under this chapter to the department are public and governmental functions, exercised for a public purpose, and matters of public necessity. All land and other property and privileges acquired and used by or on behalf of the state in the manner and for the purposes enumerated in this chapter are acquired and used for public and governmental purposes and as a matter of public necessity.