Cody Howard
School of Engineering

Study finds small aircraft face risks at airports near wind farms

Wed, 01/15/2014

LAWRENCE — A study from the University of Kansas School of Engineering sheds light on a potential safety hazard that could affect hundreds of airports across the country and calls for updated guidelines to improve aviation safety. At issue is the proximity of wind farms to general aviation airports, and how the small aircraft that use them could be affected by the turbulence generated by wind turbines.

“We’re really looking at two potential threats,” said Tom Mulinazzi, professor of civil, environmental and architectural engineering. “These turbines can set up a circular vortex that can roll a plane if it gets in there. And they can increase crosswind speeds above what’s expected, which can be a real danger to small aircraft, which don’t typically take off and land with crosswinds stronger than about 12 miles per hour.”

Mulinazzi, Professor of Aerospace Engineering Z. Charlie Zheng and his graduate student Anpeng He co-authored the report for the Aviation Division of the Kansas Department of Transportation.

By using advance computational aerodynamics modeling, the KU research team studied the effect of winds from 10-40 miles per hour. They found the higher the wind speed, the farther the turbulence reached – stretching as far as nearly three miles from a single turbine – before dissipating.

The KU team studied proposed wind farms that would be constructed near airports, one in Rooks County and the other in Pratt. At both airports, within nearly three miles of the runway, pilots could potentially encounter a crosswind or a “roll upset” generated from a wind turbine.

Mulinazzi and Zheng presented their findings at the inaugural Kansas Aviation Expo in Wichita. Mulinazzi said it appears this study is the first of its kind in the United States. Current Federal Aviation Administration guidelines only evaluate vertical structures from a static perspective within an airport zone. However, wind farms are dynamic with spinning blades that can create rotational vortices.

“The FAA reviews the potential hazard of the physical height and location of any structure, but not any of the emissions from that structure,” said Tiffany Brown, state aviation engineer with KDOT’s Aviation Division. “This research points out a shortcoming in the current evaluation process and that is why this is so important.”

KU is at the leading edge of studying this potential hazard.

“We found no research that looked at the impact of wind generated by wind farms on general aviation,” Mulinazzi said. “But KDOT tells us they’ve been getting complaints from pilots about unexpected turbulence as they approach airports near wind farms, so we felt like the study was worthwhile, especially with the boom in wind farms and wind farm proposals in Kansas.”

Kansas has about 140 public-use airports and many more private-use airports. There are 16 wind farms operating in Kansas today, but there are proposals for an additional 58, with some planned in close proximity to existing airports.

“So as state and local leaders consider these proposals for new wind farms, we’re hoping to provide them with specific information they can use to create guidelines to ensure aircraft safety. Right now, there’s really nothing on the books,” Mulinazzi said.

Previous research into turbulence generated by wind farms had shown that airplanes could briefly disappear on radar when flying near a turbine, because radar interprets the movement of the blades as precipitation, which can mask the radar return of an aircraft. No previous research had analyzed the actual impact of this turbulence on aircraft handling and performance, Mulinazzi said.

The report has been submitted to KDOT and is designed to serve as a resource for Kansas cities and counties as they consider potential regulations that govern airport airspace and safety. 

“Additional research is required to draw the true correlation between wind turbine vortices and aircraft performance,” said Jesse Romo, acting director of KDOT Aviation. “This study proves that the concern is real but we need to take it to the next level to enact change in the FAA’s evaluation process and to properly plan the location of wind farms that don’t create an environment that compromises the safe and efficient operation of aircraft at an airport.”

KU in the news
The Daily MailSat, 04/25/2015
CNNMon, 04/13/2015
Wanna Skype? Chancellor gets creative to surprise Truman winner. See it here:
Rock Chalk! Junior Ashlie Koehn named KU's 18th Truman Scholar
Ashlie Koehn, a University of Kansas junior from Burns studying in Kyrgyzstan, interrupted helping her host family prepare dinner to make a Skype call on Monday evening.

.@NYTimes columnist @WCRhoden will speak at a symposium about race and sports April 23.
Wanna Skype? Chancellor gets creative to surprise Truman winner From KU News Service: Ashlie Koehn, a University of Kansas junior from Burns studying in Kyrgyzstan, interrupted helping her host family prepare dinner to make a Skype call on Monday evening. To her surprise, Chancellor Bernadette Gray-Little was on the other end of the call letting Koehn know she had been named a 2015 Harry S. Truman Scholar. Koehn is the 18th KU student to be named a Truman Scholar and the only 2015 recipient from the state of Kansas. Earlier this month, she was also named a 2015 Udall Scholar. And in spite of a distance of more than 10,800 kilometers and 11 time zones, Koehn’s thrill from hearing the news from the chancellor came through loud and clear. “Ashlie’s experience at KU epitomizes a quality undergraduate experience. She challenged herself in her coursework, exposed herself to different research opportunities, studied abroad in Germany, Switzerland and Kyrgyzstan, and participated in both student government and community service projects,” Gray-Little said. “This is quite a year for Ashlie. Her hard work is a wonderful reflection on her and also a great reflection on the university, and we all congratulate her.” Each new Truman Scholar receives up to $30,000 for graduate study. Scholars also receive priority admission and supplemental financial aid at some premier graduate institutions, leadership training, career and graduate school counseling, and special internship opportunities within the federal government. Koehn, a member of KU’s nationally recognized University Honors Program, is majoring in environmental studies, economics and international studies. Her goal after earning her KU degree is to pursue a master’s degree in economics at either the London School of Economics or the University of Reading, with a focus on the economics of climate change. In 2014, she received KU’s Newman Civic Engagement Award for her work establishing the Coalition against Slavery and Trafficking. Her involvement with the issue was sparked by Hannah Britton, associate professor of political science and women, gender, and sexuality studies, who hosted national conference on contemporary slavery at KU three years ago. “Ashlie and I met several times to think about what KU students could contribute to the issue of slavery and human trafficking, and the result was her founding of KU CAST,” Britton said. “After a year as president, Ashlie successfully handed the organization over to the next student leader. She demonstrated her strong leadership qualities by setting a unique goal and then pursuing it with her sense of passion, engagement and dedication. No matter the country or context, her leadership strength is evident in her coursework, her public service and her work experiences.” The University Honors Program works with a campus committee to select KU’s nominees for the Truman Scholarship and supports them during the application process. Anne Wallen, assistant director of national fellowships and scholarships, noted it was an amazing ruse to pull off the surprise. Originally, the call was set up to be between Wallen and Koehn. “I was totally not prepared to be greeted by Chancellor Gray-Little, but it was an amazing surprise for sure,” Koehn said. “As a first-generation student, it took time to learn the collegiate system, but my parents taught me to be resourceful and independent from a young age and KU and the Kansas Air National Guard have provided me with the opportunities to drive me into the future, both at graduate school and in my career. I plan to use the Truman Scholarship to pursue a career as an environmental economist helping to shape future trade agreements and leverage action on important international environmental issues, particularly concerning climate change.” Koehn also had a surprise of her own for the chancellor — the meal she was helping to prepare was not exactly typical Kansas dinner fare. On the menu with her host family in Kyrgyzstan on Monday was a traditional Kyrgyz meal called Beshbarmak, or “five fingers,” because you eat it with your hands. The dish is made of horse and sheep and was being prepared as a birthday celebration for Koehn’s host mom. Chancellor Gray-Little, as she signed off from Skype, made sure to encourage Koehn to enjoy her Beshbarmak. Koehn is the daughter of Rodney and Carolyn Koehn of Burns. She graduated from Fredric Remington High School in Moundridge. She is an active member of the Kansas Air National Guard and currently on leave while studying abroad in Bishkek, Kyrgyzstan. She is a member of the KU Global Scholars Program and a past member of the Student Senate. In addition to being named a 2015 Truman and Udall scholar, she was named a 2014 Boren Scholar and Gilman Scholar and in 2013 was named the Kansas Air National Guard Airman of the Year.

One of 34 U.S. public institutions in the prestigious Association of American Universities
26 prestigious Rhodes Scholars — more than all other Kansas colleges combined
Nearly $290 million in financial aid annually
46 nationally ranked graduate programs.
—U.S. News & World Report
Top 50 nationwide for size of library collection.
23rd nationwide for service to veterans —"Best for Vets," Military Times