Wind Turbines and Safety

by Maj Ernest Herrera, Lt Col Ray King, Mr. Kevin Tibbs, and MSgt Erik Kuhlmann
Air Force Safety Center

11/19/2013 - Winter 2013/2014 -- While on a recent site visit to investigate the issue of radar returns of wind turbines on radar approach control scopes, we discovered concerns that we had never thought of during our years of operational flying (two of us are pilots). Why had we never been aware of these issues before, and how will air traffic controllers (ATCs) and pilots deal with wind turbines that seem to be popping up around their bases, low-level routes, air refueling tracks, and training areas? The weeks following the site visit concluded with a report and out-brief to our customer, but we were left with many questions that are unanswered on how our country is going to balance green energy efforts, military readiness, and aviation safety.

The research in the weeks following the site visit revealed that there has already been tremendous effort at state and national levels to address the issue of wind turbine placement and the impact on military readiness and aviation safety. These issues are not new, but we believe that our team's site visit uncovered a new angle on an already well-documented problem. In our subsequent research, we discovered that some of our concerns had been raised before, other concerns were documented that none of the team members had considered, and some of our concerns had never been addressed at all.

Previous reports addressed the impact on military readiness due to loss of training airspace. Wind turbine placement and the impact on military readiness became very evident during our site visit and in previously published studies. The very important issue of considering military training requirements can be easily dropped off the placement process because non-aviators are not intimately familiar with specific airframe training requirements and the parameters in which to optimize aircrew training. In our research, we have yet to find a process in which experts in aircrew training and readiness are involved at the beginning stages of wind turbine placement to voice major concerns about the impact on flying operations and training.

Aviation safety was a factor to consider during our site visit, and very valid concerns that range from obstacle hazards to impacts on search and rescue operations were previously voiced by others. One report discussed the potential for aircrew to miss a planned climb point and impact a wind turbine. The team agreed that this type of mishap is a possibility, as there are numerous previous Class A mishaps involving collisions with terrain obstacles.

Wind turbines' effect on radar captured the team's attention. Issues here include radar blind spots, weather radar effects, aircrew training due to loss of radar capability, antiquated radar capability, and radar upgrades. While these were interesting topics to understand, the team felt the most serious issue was not the effect on radar, but rather the human factor of false returns on ATCs and aircrew.

Wind turbines had a cause and effect scenario for both ATCs and aircrew. The wind turbines, even with radar software filtering, produce radar returns identical to aircraft without a transponder. These returns then must be acted upon by ATCs per regulations as actual aircraft traffic. The procedure is to advise aircrew of "unidentified traffic" at "unknown altitude" or to vector aircrew away from a potential mid-air collision or to delay runway departures. The aircrew, in turn, are required to visually search for this called out traffic, as well as search for traffic identified on the Traffic Collision Avoidance System on board the aircraft. In some cases, aircrew have been required to deviate course for traffic or delay their departure for traffic. ATCs and aircrew are advised to consider the tables below.

The team's concerns were on human factors surrounding the environment of flying operations and wind turbines.

Human factors affecting air traffic controllers include automation and local training issues/programs, error due to misperception, and/or ops tempo/workload.

Human factors affecting aircrew include distraction, caution/warning ignored, cognitive task oversaturation, checklist interference, and/or misinterpreted/misread instrument.
The safety team believes that the human factor errors present potential contributors, which could lead to a mid-air collision or a landing mishap due to an incomplete landing configuration. Considering all this, it is easy to understand how any combination of human factor errors and very reasonable event scenarios between pilots and ATCs could lead to a chain of events resulting in a mishap.

The team's observations are just the beginning of what could potentially be a model--not just for wind turbine placement but also an integrated approach to proactive safety when other aviation safety concerns are presented to the HQ AF Safety Center. A collaborative effort using multiple divisions from the AF Safety Center and multiple career fields is proving useful. Even more revolutionary is the role in which Military Flight Operations Quality Assurance (MFOQA) and Aviation Safety Action Program (ASAP) are being used to address safety concerns.