IMAGINARY SURFACES FOR OBSTRUCTION EVALUATION   PART 77 OBJECT IDENTIFICATION SURFACES Primary Surface: A surface longitudinally centered on a runway. When the runway has a specially prepared hard surface, the primary surface extends 200 feet beyond either end of the that runway; but when the runway has no specially prepared surface, or planned hard surface, the primary surface ends at the physical ends of the runway. The elevation of any point on the Primary Surface is the same as the elevation of the nearest point on the runway centerline. Primary surface widths vary with the classification of the runway; however, the width is uniform throughout and is based on the most precise approach existing or planned for either end of that runway. Horizontal Surface: A horizontal plane 150 feet above the established Airport Elevation, the perimeter of which is constructed by swinging arcs of specified radii from the center of each end of the Primary Surface of each runway. Tangents then connect the adjacent arcs. Size of arcs as follows: For all runways designed visual or utility, the radius of each arc is 5,000 feet. For PIR and Non-Precision Instrument Runways, the radius of each arc is 10,000 feet. The radius of the arcs specified for each end of a runway will have the same numerical value, that value being the highest determined for either end of the runway. When a 5,000 foot arc is encompassing by tangents connecting two adjacent 10,000 foot arcs, it shall be disregarded. Conical Surface: A surface, which extends upward and outward from the outer limits of the Horizontal Surface for a horizontal distance of 4,000 feet. The slope of the conical surface is 20-1 (5 percent) measured in a vertical plane.   Transitional Surface: A surface extending outward and upward, at right angles to the runway centerline and runway centerline extended, from the sides of the Primary Surface and the Approach Surfaces. The slope is 7-1 (14.3 percent) and the surface extends until it intersects the Horizontal or Conical Surface. A PIR Approach Surface that project beyond the limits of the Conical Surface extends a distance of 5,000 feet measured horizontally from the edge of the Approach Surface. The slope is 7-1 (14.3 percent). Approach Surfaces: PIR-PRECISION INSTRUMENT APPROACH A surface longitudinally centered, on the extended centerline of the PIR runway, beginning at the end of the Primary Surface and extending outward and upward at a slope of 50:1 (2.0 percent) for a horizontal distance of 10,000 feet and at a slope of 40:1 (2.5 percent) for an additional 40,000 feet. The surface width is that of the Primary Surface at the beginning and increases uniformly to a width of 16,000 feet at a distance of 50,000 feet from the end of the Primary Surface. D-NONPRECISION INSTRUMENT APPROACH VISIBILITY MINIMUMS AS LOW AS ¾ MILE A surface longitudinally centered on the extended centerline of the runway, beginning at the end of the Primary Surface. Primary Surface width at end adjacent to runway end and flaring to 4,000 feet at a distance of 10,000 ft from the end of the Primary Surface. The surface slope is 34-1 (3 percent).   C -NONPRECISION APPROACH VISIBILITY MINIMUMS GREATER THAN ¾ MILE Dimensions of the specified runway are predicated on the approach visibility minimums. A surface longitudinally centered on the extended centerline of the runway, beginning at the end of the Primary Surface. The width of this surface is 500 feet at the end of the Primary Surface and flares to a width of 3500 feet at a distance of 10,000 feet from the end of the Primary Surface. The surface slope is 34-1 (3 percent). B (V)-VISUAL APPROACH A surface longitudinally on the extended centerline of the runway, beginning at the end of the Primary Surface. The width at this point is 500 feet and it flares to 1,500 feet at a distance of 5,000 feet from the end of the Primary Surface. The surface slope is 20-1 (5 percent). A (NP)-NONPRECISION APPROACH (UTILITY RUNWAY) Utility runways with Non-Precision Approach Surfaces are not affected by visibility minimums. The width of this surface if 500 feet at the end of the Primary Surface and flares to a width of 2,000 feet at a distance of 5,000 feet from the end of the Primary Surface. The surface slope is 20-1 (5 percent). A surface longitudinally centered on the extended centerline of the runway, beginning at the end of the Primary Surface, and with dimensions predicated upon the permissible approach visibility minimums established for the specific runway end, as follows: A (V)-VISUAL APPROACH (UTILITY RUNWAY) The surface begins with a 250-feet width at the end of the Primary Surface and flares to a width of 1,250 feet at a distance of 5,000 feet from the end of the Primary Surface. The surface slope is 20-1 (5 percent)   AREA NAVIGATION APPROACH OBJECT IDENTIFICATION SURFACES Primary Surface: The surface is a 1,000 foot wide rectangular in shape and centered on the runway centerline, beginning 200 feet on the approach side of a runway threshold and extending to 200 feet beyond the opposite runway threshold. The elevation of any point on the Primary Surface is the same as the elevation of the nearest point on the runway centerline. Transitional Surface: A surface extending outward and upward, starting from the runway threshold from the edge of the Approach Surface. The surface width is 600 feet at the beginning and increases uniformly to a width of 6,376 feet at a distance of 52,000 feet from the threshold. The slope is 7-1 (14.3 percent). .   Approach Surface: ANAPC -PRECISION, CONVENTIONAL LANDING A surface longitudinally centered, on the extended centerline of the runway, beginning at the end of the Primary Surface and extending outward and upward at a slope of 50:1 (2.0 percent) for a horizontal distance of 2566 feet and at a slope of 34:1 (3.0 percent) for an additional 47,434 feet. The surface width is that of the Primary Surface (800 feet) at the beginning and increases uniformly to a width of 4,400 feet at a distance of 50,200 feet from the Threshold. Missed Approach: A surface longitudinally centered, on the extended centerline of the runway, beginning at 1300 feet outboard from the approach runway threshold, width of surface is 2,333.3 feet and 22 feet above the threshold elevation. The surface extending outward and upward at a slope of 40:1 (2.5 percent) for a horizontal distance of 7800 feet. The surface width is 2,333.3 feet at the beginning of the missed approach and increases uniformly to a width of 6,200 feet at a distance of 7,800 feet from the end of the Primary Surface. Plan view of AREA NAVIGATION APPROACH OIS Precision Approach, Primary, and Transition Missed Approach Obstruction Representation in AREA NAVIGATION APPROACH OIS Approach (first 2,566 feet) Approach (from 2,566 feet to 50,000 feet) Transition Missed Approach Obstruction accuracy requirements in AREA NAVIGATION APPROACH OIS