Correlation of Population Density to Designated Urban Areas

T HIS work relates the correlation of United States (U.S.) census population data with the designated urban areas shown on the Federal Aviation Administration (FAA) sectional charts used by visual flight rules (VFR) pilots. This will be useful for mission planning purposes for UnmannedAerial Systems (UAS). Geographic Information Systems (GIS) softwarewas used to import the raw census data andmarked urban areas from the sectional maps. This data was examined to determine the average population inside the marked urban areas and to determine how the population density reduces outside the urban areas. North Carolina State Flight Research has been developing the SystemLevelAirworthiness Tool (SLAT) [1,2], a comprehensive framework for evaluating the airworthiness of small UASwith maximum takeoff weights less than 350 lb. SLAT scales its requirements based on the size of the unmanned aircraft, aswell as the population density of themission area. The population density research presented in this technical notewas done as a part of the development of SLAT. It is expected that the results will be applicable to others in the aerospace community. To simplify analysis, SLAT divides population density into four categories: unpopulated (UP), sparsely populated (SP), densely populated (DP), andOpenAirAssembly (OAA).OAA is defined by the FAAas “an organized open-air assembly ofmore than 1,000 persons” [3], such as an occupied football stadium or outdoor concert. SP is defined by the U.S. Census Bureau as 500 people per square mile [4]. Determining the boundary between SP and DP was the goal of this work. One resource that attempts to designate a border between the two regions is the FAA sectional charts. These charts are used by pilots to aid navigation under VFRs. The sectional charts show airports, controlled airspace, antenna towers, and notable landmarks, as well as the locations and relevant information of navigation beacons. The sectional charts also include yellow regions denoting observable urban development; an example is shown in Fig. 1. Inquiries into how the FAA defines these boundaries revealed that they are defined primarily by visual inspection of satellite photos. Areas that appear to be urban, i.e. shopping centers, housing developments, and so on are included in the urban areas on the sectional charts. Although these boundaries are based on satellite photos, rather than some population density metric, it is logical that the population density would be highest in regions of observable urban development. This research focused on quantifying the correlation between actual population density and these regions of observable urban development as marked on the FAA sectional charts. One of the primary goals for SLAT is to aid in the integration of UAS into the National Airspace System (NAS) and, as such, the scope of this research is constrained to the U.S. To simplify the correlation it was decided to limit the scope to the continental U.S.