Using those basic line of sight calculations is rather useless for coloroado as the terrain comes into play. I actually was looking at a site that though it was the highest spot for miles, it was in a valley an hour or so south of the OP and would cover the county entirely, but only 10 miles west, 10 miles east, and 15 north due to mountains and the gorge the Arkansas River cut its way through. The basic calculations work well in this kind of terrain. http://uploads.tapatalk-cdn.com/20160320/448d567f980191559ddc4e964f70b5ed.jpg That grain elevator is 8 miles away and roughly 200 feet tall. Sent from my iPhone using Tapatalk