(a) Except as provided in paragraph (b) of this section, no person may
operate a moored balloon or kite --
(1) Less than 500 feet from the base of any cloud;
(2) More than 500 feet above the surface of the earth;
(3) From an area where the ground visibility is less than three miles;
(4) Within five miles of the boundary of any airport.
(b) Paragraph (a) of this section does not apply to the operation of a
balloon or kite below the top of any structure and within 250 feet of it,
if that shielded operation does not obscure any lighting on the structure.