Newly-released federal reports indicate that glare from California’s Ivanpah Solar Electric Generating System in San Bernardino County poses an aviation risk for those flying between Los Angeles and Las Vegas.

The federally-funded Sandia National Laboratories report, which was released on July 17, shows that mirrored heliostats, which use energy from the sun to reflect heat onto the 397-megawatt solar power tower plant, produce dangerous glare when they are placed in “standby” mode, according to KCET. 

The report, entitled “Evaluation of Glare at the Ivanpah Solar Electric Generating System,” says that when the heliostats are in standby position (which means they are not aimed directly at the plant’s boilers but rather towards the sky), they “can cause visual afterimages for observers as distant as six miles from the power plant.” This could pose potential problems for pilots flying in the airspace over the Ivanpah Valley. 

In March of this year, KCET wrote a story about pilots who were complaining that glares from the mirrors were interfering with crews’ ability to scan the sky for nearby aircraft, potentially resulting in mid-air collisions. Approximately 120 commercial aircraft reportedly fly between McCarran and Los Angeles-area airports during the week. The figure does not include a large number of private aircraft, which KCET notes fly through the region’s Mojave skies.

In May, “California Department of Transportation aeronautics chief Gary Cathey said in an email to the California Energy Commission (CEC)… that a May 8 overflight of the Ivanpah plant ‘generated the brightest, most extensive amount of glare that I’ve seen in my aviation career — and I have been flying since 1986.'”

In March, the Ivanpah plan’s owner, Energy Services, issued a response to state regulators that the mirrored heliostats had not yet been “calibrated,” which is why the glare was occurring, notes KCET. The issue has yet to be fixed.

Another facility, called the Palen Solar Electric Generating System, is being considered for approval by the CEC. The Palen facility would be significantly larger than the one in Ivanpah and yield similar and presumably even greater glare problems. An in-depth analysis of the situation at hand can be found here on the KCET website. Those hearings are reportedly scheduled to take place in Blythe, CA  between July 29-31.