How should UA pilots operate when surveying tall structures that extend into Class E airspace?

When surveying tall structures that extend into Class E airspace, unmanned aircraft (UA) pilots can operate without requiring authorization from air traffic control (ATC) as long as they remain below 400 feet. This regulation aligns with the guidelines for operating UAs under the current FAA rules, which allow operations below 400 feet in uncontrolled airspace without the need for ATC permission.

Class E airspace generally allows for operations unless restrictions are imposed by ATC, and the 400-foot threshold is significant because it defines the altitude limit for many recreational and commercial UAV operations. Pilots maintaining their flight below this altitude can ensure they are not interfering with manned aircraft operations, which are typically at higher altitudes. This regulation also promotes safety and efficiency in airspace utilization, especially in areas where tall structures may create hazards.

While the other options present valid considerations, such as safety during specific times (daytime ops) and permissions in certain airspace scenarios, the fundamental operational limit of 400 feet underlines the autonomy that UA pilots have in Class E airspace, reinforcing why remaining below this threshold negates the need for prior ATC permission.