NIGHT SKY AND DARK ENVIRONMENTS: BEST MANAGEMENT PRACTICES FOR ARTIFICIAL LIGHT AT NIGHT ON BLM-MANAGED LANDS TECHNICAL NOTE 457 65 5.6.6 For Tall Structures, Use Flashing Warning Lights at Night, and Replace Nonflashing with Flashing Lights Research shows that steady-burning lights on tall structures are more disorienting to wildlife than flashing lights (Gehring et al. 2009), and it is important to avoid their use wherever possible. Using flashing lights (low flash rate lights are best) reduces ecological effects and prolongs the light source’s operating time while reducing energy consumption. Where feasible, and consistent with FAA requirements and safety considerations, replace nonflashing lights with flashing lights (e.g., on communications towers and other tall structures). The FAA has revised its advisory circular (FAA 2015) that prescribes tower lighting to reduce bird collisions. See FCC 2017 for additional information. Notes: In addition to reduced effects on wildlife, flashing lights are more noticeable to pilots. LED street lighting system shown at initial startup at dusk (left) and 50 percent dimmed after midnight (right). WSP/Parsons Brinkerhoff Communications tower at night with red lights.
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