On a periodic basis, FAA Flight Procedures collects data on airport obstructions and shares this information with individual airports. Airport managers typically receive an email that includes one or more spreadsheet summaries of surface penetrations, and a Google Earth (.kml) file that presents the penetrations graphically. While this information is useful for long-term maintenance of obstructions, Gale Associates, Inc. has received inquiries from airport clients regarding how to best understand and use this information. Gale offers the following guidance for our airport clients:
Know Your Surfaces. FAA will often send obstruction data for more than one runway approach surface. This may give the impression that there are obstructions that need to be removed, when in fact, that approach surface may not apply. Each airport manager should be familiar with the approach surfaces that are to remain clear. Only the appropriate files sent by FAA should be used to identify and clear obstructions as part of the airport’s maintenance program.
Smart Spreadsheets. The spreadsheets sent by FAA include a lot of useful information to help identify and locate obstructions. Information regarding ground elevation, obstruction heights, and the severity of surface penetration is included. Airports can use the Latitude and Longitude coordinates provided to locate obstructions in the field. The knowledgeable and careful use of an affordable hand-held GPS unit may be useful in assisting the airport in validating the location of obstructions in the field.
Get Google Earth. This useful tool must be installed on your computer in order to open the .kml files sent by FAA. You can download the latest version of Google Earth here. Only the .kml files that correspond to the applicable surfaces should be used. These files show the location of each identified obstruction overlaid on an aerial photo. Airports can use this tool to best identify and plan their obstruction maintenance activities. It should be noted that the .kml files sent by FAA are preset to show an oblique perspective of the obstructions, which may appear to distort the obstructions’ actual locations. To show the obstructions in an overhead view, use the navigation tools in the top right of the Google Earth screen. The oblique angle can be adjusted using the arrows circled in the image to the right.