(b) Heliport approach surface. The approach surface begins at each end of the heliport primary surface with the same width as the primary surface, and extends outward and upward for a horizontal distance of 4,000 feet where its width is 500 feet. The slope of the approach surface is 8 to 1 for civil heliports and 10 to 1 for military heliports.
(c) Heliport transitional surfaces These surfaces extend outward and upward from the lateral boundaries of the heliport primary surface and from the approach surfaces at a slope of 2 to 1 for a distance of 250 feet measured horizontally from the centerline of the primary and approach surfaces.
[Doc. No. 1882, 30 FR 1839, Feb. 10, 1965, as amended by Amdt. 77–9, 36 FR 5971, Apr. 1, 1971; 36 FR 6741, Apr. 8, 1971]