The establishment and continued maintenance and operation of safe, adequate and necessary public airports and public airport facilities within the State of Illinois and the creation of airport authorities having powers necessary or desirable for the establishment and continued maintenance and operation of such airports and facilities are declared and determined to be in the public interest, and such powers and the corporate purposes and functions of such authorities, as herein stated, are declared to be public and governmental in nature and essential to the public interest.
70 ILCS 5/7