National Association of Broadcasters Engineering Handbook, 11th Edition

Chapter1.3

Distance and Bearing Calculations

Dane E. Ericksen, P.E.

Hammett & Edison, Inc., Consulting Engineers

San Francisco, CA

Introduction

The current FCC Rules for distance calculations use two methods: “flat-earth” and “spherical-earth.” The flat-earth method assumes the distance between two points to be the hypotenuse of a right triangle whose sides are determined by the difference in latitude and longitude of the starting and ending points multiplied by the length per degree of latitude and longitude at the mid-latitude of the two points, as shown in Figure 1.3-1.

The “flat-earth” term is not meant to be disparaging, and merely refers to the use of a right triangle to calculate the distance. Because the lengths of a degree of longitude ...