extending higher than 2,000 feet AGL. Most skeletal structures are supported by guy wires which are  very difficult to see in good weather and can be invisible at dusk or during periods of reduced visibility.  These wires can extend about 1,500 feet horizontally from a structure; therefore, all skeletal structures  should be avoided horizontally by at least 2,000 feet. Additionally, new towers may not be on your current chart because the information was not received  prior to the printing of the chart.  Remote Pilot – Small Unmanned Aircraft Systems Study Guide  70 Chapter 11: Airport Operations 