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
Human factors affecting aircrew include distraction, caution/warning
ignored, cognitive task oversaturation, checklist interference, and/or
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.