Permits Required. No material change shall be made in the use of land, and no structure or tree shall be erected, altered, planted, or otherwise established in any zone created by this article unless a permit therefor shall have been applied for and granted by the executive director. However, no permit shall be required for any tree or structure of less than 75 feet of vertical height above the ground in the horizontal and conical zones or in any approach and transitional zones beyond a horizontal distance of 4,200 feet from each end of the runway except when such tree or structure, because of terrain, land contour, or topographic features, would extend above the height limit prescribed for the respective surfaces or be determined to interfere with any airport navigational equipment. Source: PL 4-10, § 7.