• The Primary Surface is an area in the immediate vicinity of the landing or takeoff area , forming a large rectangle around the entire active runway area . It extends 200 feet in length past the end of the runway , which is the displaced threshold at Keesler AFB . The primary surface associated with the Keesler AFB runways is 2,000 feet wide , which means that the surface measures 1,000 feet wide on either side of the runway centerline .
• The Inner Horizontal Surface is an oval‐shaped area that surrounds the runway at a height of 150 feet above the established airfield elevation . It measures a total of 15,000 feet wide , including the area above the runway . It extends 7,500 feet out from the centerline of the runway and forms a half‐circle at the runway ends .
• The Conical Surface is an oval‐shaped area 7,000 feet wide , connecting the outside edge of the Inner Horizontal Surface to the inside edge of the Outer Horizontal Surface . It slopes from the Inner Horizontal Surface to the Outer Horizontal Surface at a ratio of 20:1 , meaning that it extends 20 horizontal feet for every one vertical foot .
• The Outer Horizontal Surface is an oval‐shaped area that measures 30,000 feet in width out from the farthest edge of the conical surface . The height of the Outer Horizontal Surface is 500 feet above the established airfield elevation .
• Transitional Surfaces connect the primary surfaces , the first 200 feet of the clear zone surfaces , and the approach clearance surfaces to the inner horizontal surface , conical surface , outer horizontal surface or other transition surfaces . This connection is sloped at a ratio of 7:1 , meaning that it extends seven horizontal feet for every one vertical foot .
Additionally , Keesler AFB adheres to the following imaginary surface area :
• Displaced Thresholds are the functional run allowed before the displaced threshold . A of the runway , the displaced threshold is lo end of the runway pavement . At Runway 2 runway , the displaced threshold is located the runway pavement .
FAA Part 77 Obstruction Evaluation Area In addition to the imaginary surfaces established Aviation Administration ( FAA ) has also establishe potential for accidents surrounding an airfield . A surfaces of an active airfield and in relation to flig airport ( military or civilian ), vertical obstructions compliance with the Code of Federal Regulation ( establishes standards and notification requireme navigable airspace . A key reference used for com following :
• A height that is 200 feet AGL or above the elevation , whichever is higher , within 3 nau reference point of an airport , excluding he runway more than 3,200 feet in actual leng the proportion of 100 feet for each additio from the airport up to a maximum of 499 f
Figure 3‐9 illustrates the Part 77 footprint based runway .
Commonly referred to as Part 77 compliance , thi to evaluate the potential for a vertical obstructio the airfield , the height and resulting elevation of and the location of the structure or facility in rela question . The guidance and process for obstruct detailed in Chapter 4 , Existing Tools under federa
Background Report