Inner approach, inner transitional, and balked landing obstacle limitation surface.
The outer-horizontal, conical, inner-horizontal, approach, inner-approach, transitional, inner-transitional, balked-landing, and takeoff climb surfaces make up the obstacle-limitation surfaces. The outer-horizontal surface is a plane located 500 ft (150 m) above the established airfield elevation, extending outward from the outer periphery of the conical surface for a distance of 30,000 ft (9000 m). The conical surface extends from the periphery of the inner-horizontal surface outward and upward at a slope of 20 to 1 for a horizontal distance of 7000 ft (2100 m) to a height of 500 ft (150 m) above the established airfield elevation. The inner-horizontal surface is a plane that is oval in shape at a height of 150 ft (50 m) above the established airfield elevation. The plane is constructed by scribing an arc with a radius of 7500 ft (2250 m) about the centerline at the end of each runway and interconnecting these with arcs at the tangents. The approach surface is an inclined plane or combination of planes preceding the threshold. The inner-approach surface is a rectangular portion of the approach surface immediately preceding the threshold. The transitional surfaces connect the primary surfaces, the first 200 ft (60 m) of the clear zone surfaces, and the approach clearance surfaces to the inner-horizontal surface, conical surface, outer-horizontal surface, or other transitional surfaces. The slope of the transitional surface is 7 (horizontal) to 1 (vertical) outward and upward at right angles to the runway centerline. The inner-transitional surface is similar to the transitional surface but closer to the runway. The balked-landing surface is an inclined plane located at a specified distance after the threshold, extending between the inner- and outer-transitional surfaces. The takeoff climb surface is an inclined plane or another specified surface beyond the end of the runway or clearway.