Earlier this year, a single engine plane collided with a wind turbine in Germany killing the pilot and shattering the aircraft. The appalling tragedy was reported as a rare occurrence, but few realize that in the U.S. alone at least ten people have lost their lives in fatal aviation accidents involving collisions with U.S. sited wind turbines and meteorological (MET) towers.
The table below lists these accidents, six in all.
|Dec 15, 2003||Vansycle, OR||Yes, 2||Transport (MET)||NTSB Accident ID SEA04LA027|
|May 19, 2005||Ralls, TX||Yes, 1||Ag Spray (MET)||NTSB Accident ID DFW05LA126|
|Jan 10, 2011||Oakley, CA||Yes, 1||Ag Spray (MET)||NTSB Accident ID WPR11LA094|
|Aug 5, 2013||Balko, OK||Yes, 1||Ag Spray (MET)||NTSB Accident ID CEN13FA465|
|Apr 27, 2014||Highmore, SD||Yes, 4||Transport (Turbine)||NTSB Accident ID CEN14FA224|
|Aug 19, 2016||Ruthton, MN||Yes, 1||Ag Spray (MET)||NTSB Accident ID CEN16LA326 |
Wind and Collisions
The most widely reported incident occurred the night of April 27, 2014, just ten miles south of the airport in Highmore, South Dakota. All four passengers, including the pilot, were killed when their plane struck an operating wind turbine owned by NextEra. According to the National Transportation Safety Board (NTSB) report, the facility was not marked on the sectional charts covering the accident location.
NTSB also reported that the light on the turbine tower was not operational at the time of the accident, and the outage was not documented in a notice to airmen (NOTAM). NTSB investigators opined that “[i]f the pilot observed the lights from the surrounding wind turbines, it is possible that he perceived a break in the light string between the wind turbines as an obstacle-free zone.”
The other five incidents involved collisions with wind project meteorological (MET) towers. MET towers are erected at proposed wind energy sites for assessing wind speed and direction. The towers, made from galvanized tubing 6-8 inches in diameter and secured with guy wires, can be erected in a matter of hours and, in many cases, without notice to the local aviation community. Their rapid deployment means the navigable airspace of an area could quickly become hazardous for low-flying aircraft. Generally, the towers stand under 200-feet, thus below the threshold for requiring FAA notification, are unlit and usually devoid of any markings, so they are difficult to see.
In the three fatalities from 2003, 2005, and 2011, final NTSB reports cited the unmarked towers and the inability of the pilot to see the towers as the probable causes for the accidents. In the 2013 fatality, the MET tower was marked but sun glare impaired the pilot’s ability to avoid the tower.
NTSB Recommendations and FAA Delays
The NTSB is well aware of the hazards these towers pose. On May 15, 2013, the agency filed the following safety recommendations with the FAA related to MET tower aviation risks: 
- Amend 14 [CFR] Part 77 to require that all [METs] be registered, marked, and—where feasible—lighted.
- Create and maintain a publicly accessible national database for the required registration of all [METs].
The FAA delayed acting on its MET-tower safety recommendations claiming limited resources and competing priorities so it wasn’t until December 2015,  before updated rules for marking MET towers were released. Still, the FAA stopped short of mandating them. Eight months later (August 2016), a 6th fatality occurred when a pilot collided with an unmarked MET tower in Minnesota.
Following FAA’s delays, Congress acted by passing the “FAA Extension, Safety, and Security Act of 2016,” which mandates that towers between 50 and 200-feet having an above-ground base of 10-feet or less in diameter be marked. Specific provisions in the bill explain the types and location of towers for which the law applies. The FAA is again tasked with creating rules to implement the regulation  but with a deadline of July 2017.
Encroachment and Fatal Risks
Other aviation fatalities have happened involving wind turbines but without direct collisions and where blame was attributed to the pilot. One such incident occurred on February 8, 2008 when Philip Ray Edgington, an experienced American Airlines pilot, was flying his vintage Cessna 140 airplane near Grand Meadow, Minnesota, at an elevation between 300 and 600 feet above ground level (agl).
On that fatal day, Mr. Edgington came upon an array of 400-foot tall turbines, whereupon “the airplane made a 90-degree course change, which was followed by a figure-8 turn at varying altitudes between 800 and 1,500 feet agl.” The NTSB reported that the craft “impacted terrain in a nose-low, left-wing-down attitude. The 300-foot-long debris path and fragmentation of the airplane were consistent with a high-speed impact.”
The probable cause of the accident according to the NNTSB was “The pilot’s continued visual flight into an area of known instrument meteorological conditions in an airplane not equipped for instrument flight, and his failure to maintain control of the airplane while maneuvering at low altitude.”
Pilot error may be the strict legal explanation for the accident, but there should be no question the wind turbines played a role.
Wind turbines and associated MET towers are encroaching on aviation air space, and safety concerns are growing worldwide. In September 2015, Royal Air Force pilots produced a catalogue of near misses with wind farms in the United Kingdom. Recreational and light-craft pilots are also sounding the alarm. According to microlight aircraft instructor Colin MacKinnon in the UK, millions have been spent “to investigate the impact and guarantee the safety of commercial aviation” but “very little has been done for the general aviation sector which is us.” The general aviation sector is the primary user of low-elevation flight space.
As the Trump Administration undertakes its review of existing agency rules, we recommend the following actions be considered in order to secure the safety of our airspace for all aviators.
- FAA quickly adopt new rules governing the safe siting of wind MET towers; Mandate that rules apply immediately to all new and existing MET towers unless specifically exempted by law;
- Mandate full review and update of SkyVector sectional charts to ensure wind turbine installations and MET towers are correctly represented;
- Follow the NTSB recommendation to create and maintain a national database of wind-related towers with full public access;
- Institute periodic review and enforcement to ensure all FAA required turbine safety equipment including lighting is operating properly. Apply punitive fines for developers who fail to maintain all safety equipment.
 We note that the NTSB preliminary report makes no mention of the met tower, only the guy wire.
 NOTAM: a written notification issued to pilots before a flight, advising them of circumstances relating to the state of flying.
 Special Investigation Report on the Safety of Agricultural Aircraft Operations NTSB/ SIR-14/01 PB2014-105983 Notation 8582 Adopted May 7, 2014 (Recommendations were also filed with the American Wind Energy Association (AWEA), Department of the Interior (DOI), U.S. Department of Agriculture (USDA), Department of Defense (DOD), 46 states, 5 territories, and the District of Columbia.)
 Advisory Circular U.S. Department of Transportation Federal Aviation Administration, Obstruction Marking and Lighting December 4, 2015, AC No: 70/7460-1L
 NAAA Newsletter: Everything You Need to Know About New Tower Marking Requirements.