The Federal Aviation Administration (FAA) serves a historically important role in the mitigation of hazards to air navigation in the U.S. Thus, it was no surprise when the FAA addressed safety issues that arose from the construction of wind turbines, singularly or as part of a wind farm. The FAA’s Advisory Circular No: 70/7460-1L (2015) (Chapter 13: Marking and Lighting Wind Farms) specifically identified the height at which a turbine becomes an obstruction and, ultimately, a hazard to safe air navigation during all phases of construction, from start to finish. Given the vast ranges of topography throughout the continent, safety concerns are real, with the potential for a deadly consequence, as witnessed in past turbine/aircraft accidents. The FAA guidance gives wind turbine contractors and owners the predictability and clear guidance to plan airspace hazard mitigation early on in their projects.
In the AC 70/7460-1L, the FAA recommended that turbine owners become familiar with the different types of lighting systems and specify the necessary type of lighting system required. Lighting system manufacturers responded to the FAA’s recommendation by designing lighting to fit specific purposes and requirements.
Engineering and construction firms, however, are ultimately the parties responsible for the installation of required lighting and are open to FAA inspection and enforcement of marking and lighting requirements on turbines once a height of 200 feet (approximately 61 meters) is reached (typically achieved during the construction phase). The FAA lighting recommendations apply to both single wind turbines and entire farms. Achieving safe, navigable airspace for all pilots is the FAA’s ultimate objective in setting turbine visibility or conspicuity lighting standards. Again, the consequences can result in an aircraft collision and significant liability to the wind farm owner, general contractor or erector.
Nighttime conspicuity of a turbine under construction becomes clearer with the update to the FAA guidelines. To ensure turbines are marked as a hazard once they reach 200 feet, and well before the obstruction is marked on FAA aeronautical charts, pilots must be visually warned that an under-construction wind turbine is within their flight path. The purpose of the FAA’s installed and operational temporary lighting requirement is simple: hazard elimination and safety. It is also why only those marking and lighting systems that meet established technical standards are recommended in AC 70/7460-1L. Hazard conspicuity and aircraft safety are critical enough that the FAA specifically prohibits a Notice to Airmen as a substitution for temporary turbine lighting. Simply put, there is no substitute for a steady-burning red light.
While a turbine is under construction, temporary lighting is a basic and mandatory minimum requirement once a height of 200 feet is reached. The temporary lighting requirement is for an FAA-compliant L-810 steady-burning red light. For a turbine under construction, the FAA-compliant L-810 is the only temporary lighting solution to ensure a turbine’s nighttime conspicuity until the installation and operation of permanent lighting can be achieved, but the permanent lighting configuration will vary slightly according to the height of the rotor tip at top dead center. FAA-certified and -listed L-864 synchronized flashing red lights are the mandatory permanent lighting solution when power allows, but that is not always possible during the construction phase, as power may be intermittently available. During this construction phase, when permanent power is not available for the permanent obstruction light, the FAA has included an important amendment.
Chapter 13.8 of the AC 70/7460-1L guidelines (Lighting of Wind Turbines During Construction Phase) allows the use of a “self-contained, solar-powered, LED, steady-burning red light that meets the photometric requirements of an FAA L-810 lighting system.” FAA certification of the temporary lantern is not required by the FAA, but the solar-powered light must be compliant with the photometric requirements of the FAA’s AC 150/5345-43H for certified lighting. These minimum specifications are designed to provide a universal functionality among manufacturers and to ensure vital performance indicators are met, including those for vertical beam spread (of 360°); candela intensity (32.5 candelas); autonomy (seven days); and lux levels, a measure of light intensity.
Because a turbine’s lighting requirements change as its height does during the construction period (as it evolves from temporary, during construction, to permanent, upon completion), lighting selection is a vitally important consideration when evaluating compliance issues.
Besides selecting temporary and permanent lighting, making the right mounting selection can also have an effect on safety. Mounting brackets and hardware that are universal from the temporary-to-permanent marking offer safety benefits. In 2015, an independent federal agency noted the results when using aftermarket products from various manufacturers as an inoperative hazard light.
Another unintended benefit of universal mounts is increased safety for erectors, climbers and maintenance personnel. Crews can ascend with no duplication of mounting hardware and with fewer tools. That translates into less time aloft for crews when changing, adding or maintaining FAA lighting. No matter how competent a climber, eliminating excess equipment weight and unnecessary time aloft helps reduce the potential for injury. With an estimated 100,000 turbines needed to help satisfy demand for electricity by 2033 (according to the American Wind Energy Association), safety advances become critical.
FAA-compliant and -certified obstruction lighting and universal mounts offer the benefits of reduced installation and maintenance time and the potential to add to the safety of rigging personnel. The ability to offer different lights, across multiple platforms (varying use and heights), through all phases (from construction to- completion) is how lighting manufacturers can offer turbine engineers and constructors the best financial return on their lighting investments, with the added benefit of a safer platform aloft and full FAA compliance and/or certification across all lighting products.
Purchasing economies; safety; and high-quality, FAA-compliant lighting can be successfully packaged together to mark wind farms, no matter how large or small the wind farm, when all aspects of turbine lighting requirements are carefully considered.
Jason Larrere is sales executive at Avlite Systems. He can be reached at firstname.lastname@example.org.