Many structures exist that could significantly affect the safety of your flight when operating below 500' AGL and particularly below 200' AGL, despite FAR 91.119 allowing flight below 500' when over sparsely populated areas or open water
At and below 200' AGL, you are operating close to power lines, antenna towers, etc., which may or may not be lit
Notice to Air Missions (NOTAMs) will typically be published for unlit structures, but pilot vigilance is imperative in case the FAA has not yet been notified of outages
Obstacles to Flight:
Obstacles that extend more than 200 feet AGL are typically shown on sectional charts unless they are within the yellow tint of a city
Antenna Towers:
Communication Antennas
Numerous skeletal structures, such as radio and television antenna towers, exceed 1,000' or 2,000' 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
Overhead Wires:
Transmission and utility lines often span approaches to runways and natural flyways, such as lakes, rivers, gorges, and canyons, and cross other landmarks pilots frequently follow, such as highways, railroad tracks, etc.
Supporting structures such as guy wires exist here as well
Some locations identify these obstructions with unique sequencing flashing white strobe light systems
However, many power lines do not require notice to the FAA and, therefore, are not marked and/or lighted
Many of those that do require notice do not exceed 200 feet AGL or meet the Obstruction Standard of 14 CFR Part 77 and, therefore, are not marked and/or lighted
Pilots are cautioned to remain extremely vigilant, especially in the case of seaplane and/or float-equipped aircraft
Wind Turbines:
Sectional Depiction of Wind Farms
Wind turbines are becoming increasingly preveland as one method in the shift to renewable energy
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Wind turbines are typically below 500 feet, but some may be significantly higher, even encroaching into Class E airspace
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Turbines or groups of turbines (1 out of 3 must be lit) have red flashing lights placed on top of the turbine nacelle (note the blade is higher)
Wind farms are depicted on sectional charts with a boxed number indicating the maximum elevation figure
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Sectional Depiction of Wind Farms>
Unmanned Balloons:
Key West Balloon Hazard
The majority of unmanned free balloons currently being operated have, extending below them, either a suspension device to which the payload or instrument package is attached, or a trailing wire antenna, or both
You can expect restricted airspace established in the vicinity of these balloons
Good judgment on the part of the pilot dictates that aircraft should remain well clear of all unmanned free balloons, and flight below them should be avoided at all times
Pilots are urged to report any unmanned free balloons sighted to the nearest FAA ground facility with which communication is established to assist FAA ATC facilities in identifying and flight-follow unmanned free balloons operating in the airspace
Key West Balloon Hazard
Conclusion:
There are other objects or structures that could adversely affect your flight, such as construction cranes near an airport, newly constructed buildings, new towers, etc.
Many of these structures do not meet charting requirements or may not yet be charted because of the charting cycle
Some structures do not require obstruction marking and/or lighting, and some may not be marked and lighted even though the FAA recommended it
