Solar and Airports

Due to the close proximity of the solar project to the airfield, which is also in the flight path of arriving aircrafts, the applicant prepared a reflectivity analysis of the potential impacts of glare on aircrafts on final approach to the airfield. The analysis showed that while there is a potential for an after-image, that effect occurs when aircrafts are perpendicular to the glare source and would be a brief occurrence in the pilots’ peripheral view. The FAA issued a “determination of no hazard to air navigation” for the project in March.

With over 30 solar projects operating at airports in 15 different states, the success of the airport-solar partnerships has been well established. Evolving FAA requirements over the past year have introduced uncertainty to the approval process, which has caused project proponents to question if the FAA would stop approving projects altogether due to its concern about the potential impacts of glare.

Projects have continued to be approved, and the recent introduction of the SGHAT model as an FAA-recommended method for assessing glare impacts has provided the solar industry with specific direction on how the issue must be assessed. With clear guidance for glare modeling in place, it should be smooth flying for future airport solar projects. 

 The FAA has established informal guidelines for how SGHAT should be used so that the agency can determine how glare affects controllers who are working in air traffic control towers (ATCTs) and pilots who are arriving at the airport on final approach.

Once the area of the solar project is located and its design characteristics recorded, information on each of the glare-sensitive receptors must be input. The ATCT is identified on the same map as the solar project as an observation point, and the height on the tower is inserted. At remote airports that do not have a tower, this observation point can be skipped, and an analysis of impacts on the ATCT is not necessary.

The SGHAT analysis for aircrafts arriving on final approach is a bit more complicated. The FAA is interested in the potential effects of glare on pilots from two miles away from the runway to touchdown. Because SGHAT only analyzes specific points and not lines, observation points along the final approach path must be selected. Aircrafts on arrival fly along a three-degree glide slope. Current FAA guidance indicates that points should be established at quarter-mile increments out to two miles, resulting in eight observation points for each runway end. The observation points are located based on distance from touchdown and height above ground when traveling on the glide slope.

The SGHAT analysis for aircrafts arriving on final approach is a bit more complicated. The FAA is interested in the potential effects of glare on pilots from two miles away from the runway to touchdown. Because SGHAT only analyzes specific points and not lines, observation points along the final approach path must be selected. Aircrafts on arrival fly along a three-degree glide slope. Current FAA guidance indicates that points should be established at quarter-mile increments out to two miles, resulting in eight observation points for each runway end. The observation points are located based on distance from touchdown and height above ground when traveling on the glide slope.

The FAA has established performance standards to guide its determination of the significance of a glare hazard. For the ATCT, the project must produce no potential for an ocular hazard or glare. For aircrafts on final approach, the project must produce a low potential for a temporary after-image (i.e., brief loss of vision when exposed to glare), although exceptions may be made based on the location of the glare source relative to the pilot’s straight-on view to the runway.

Any project not meeting these standards will be objected to by the FAA and will receive a “determination of presumed hazard.”

Case in point

One of the first solar projects to be approved using SGHAT was a 1 MW solar facility at the corporate offices of Bidart, an agricultural company, in Shafter, Calif. The corporate facilities are located on private land directly across the road from Shafter-Minter Field, a relatively small general aviation facility.

Due to the close proximity of the solar project to the airfield, which is also in the flight path of arriving aircrafts, the applicant prepared a reflectivity analysis of the potential impacts of glare on aircrafts on final approach to the airfield. The analysis showed that while there is a potential for an after-image, that effect occurs when aircrafts are perpendicular to the glare source and would be a brief occurrence in the pilots’ peripheral view. The FAA issued a “determination of no hazard to air navigation” for the project in March.