What are the orange balls on power lines in Charlotte? Think of air travel
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Some driving near Charlotte Douglas International Airport may have noticed orange balls hanging from power lines.
Though some believe the balls are used to weigh down power lines to avoid wind movement or for speed surveillance, neither of those theories is true.
Those balls are called visibility markers, or marker balls, and they are important tools used for aircraft safety and protecting electrical infrastructure.
What are visibility markers used for?
Spherical visibility markers are placed on power lines to make them visible to pilots, Shulie Tornel wrote for Edison International, a California-based utility company.
The markers, which weigh about 17 pounds each and are 36 inches in diameter, are usually found near major freeway crossings and around airports, according to Tornel.
“The conductors and skyline wires become almost invisible against the terrain when flying,” Tornel wrote. “Moreover, helicopters and small planes often fly low in mountain passes or over freeways when approaching airports.”
The Federal Aviation Administration lists power lines as a potential flight hazard since some “are not marked and lighted as obstructions and may not be seen in time to avoid a collision.”
Unmarked power lines can also pose a threat to helicopter pilots, data show. A report from the Department of Homeland Security found that power lines claim an average of two helicopters per week and account for approximately 5% of all helicopter accidents.
What are the policies for visibility marker installation?
The Federal Aviation Administration requires the markers to be orange, white or yellow, and spaced along power lines in 200-foot intervals.
To make the markers more visible, the FAA says markers should be installed in alternating patterns of orange, white and yellow. However, when less than four markers are used, all of them should be orange, according to the FAA.
