Wind energy and aviation: a growing conflict of interest
The expansion of renewable energies is one of the central infrastructure projects for many countries. Wind energy in particular plays a key role in this. Modern wind turbines today reach overall heights of more than 250 metres, thus exceeding the dimensions of many structures that were considered exceptional only a few years ago.
In parallel, aviation is also continuously developing. Modern instrument landing procedures, satellite-based navigation, more powerful aircraft, and increasing demands on flight safety mean that the interactions between aviation and wind energy are becoming increasingly complex.
While previously the question often focused solely on whether a wind turbine protruded into an obstacle surface, current regulations take a much more comprehensive view of the situation.
ICAO is modernising its obstacle lighting guidelines
With the new edition of the handbook, the ICAO is responding to the changed circumstances. The previous version originated from a time when wind turbines were significantly smaller and many of the navigation and surveillance systems used today did not yet exist.
The new edition takes a holistic approach. Instead of solely considering the physical presence of an obstacle, its impact on airfield operations and technical infrastructure is now also assessed.
This recognises that modern wind farms can have a far greater impact on air traffic than a single structure of the same height.
More than just an obstacle on approach
The ICAO expressly notes that wind turbines must not be considered merely as static obstacles. Their effects extend significantly further.
The air currents generated by large rotors are particularly relevant. Complex turbulence fields arise behind wind turbines, which can reach considerable dimensions depending on wind direction and weather conditions. These so-called wakes can influence the flight stability of particularly lighter aircraft.
For general aviation, this aspect is of particular importance. Aircraft in circuit patterns, training flights or approaches to smaller airfields often move at comparatively low altitudes and can therefore be more affected by local air currents than airliners in cruise flight.
Greater focus on turbulence and wind shear
For the first time, the ICAO is dedicating extensive chapters to turbulence and wind shear in connection with wind turbines. Studies have shown that large wind farms can influence local wind conditions, partly over several kilometres.
Situations with crosswinds or changing wind directions are particularly critical. Here, turbulence can develop in areas relevant to take-offs and landings. Go-around manoeuvres, which are already among the most demanding phases of flight, can also be additionally affected by this.
For airport operators, this means that more detailed investigations may be required in future before wind energy projects in the immediate vicinity are approved.
Effects on navigation and radar systems
Another focus of the new guidelines concerns technical systems. Modern flight procedures are increasingly based on precise navigation aids and monitoring equipment.
Wind turbines can cause various technical effects due to their size and rotating rotor blades. These include reflections and interference of radar signals, as well as potential influences on radio and navigation systems.
This can have significant consequences, especially at airports with instrument flight procedures. Even minor disruptions can necessitate the adaptation of procedures or an increase in safety distances.
Blend effects are being considered comprehensively for the first time.
A comparatively new topic in aviation is the so-called "blinding effect". Modern wind turbines have large, bright surfaces that can reflect sunlight.
Under certain conditions, these reflections can affect pilots, air traffic controllers, or operators of technical facilities. While glare has hitherto often only been discussed in connection with photovoltaic installations, ICAO now also expressly includes wind turbines in its assessments.
New Category: Non-physical Hazards
Particularly noteworthy is the inclusion of so-called „non-physical hazards“ in the ICAO guidelines. With this, the organisation significantly expands the classic definition of obstacles.
It is no longer solely the actual height of an object that determines its relevance to aviation safety. Indirect effects on procedures, technical systems, or the future development of an airfield must also be taken into account in the future.
This approach is likely to fundamentally change the assessment of construction projects near airports.
Aeronautical studies are gaining importance
At the heart of the new guidelines are so-called aeronautical studies. These are comprehensive safety engineering assessments used to analyse the impact of a project on flight operations.
Such studies consider not only current flight procedures but also future development possibilities for an airfield. This is intended to prevent current construction projects from permanently restricting later expansions or new approach procedures.
For wind farm operators, this means a higher planning effort, but at the same time also greater transparency regarding aviation-related requirements.
Impacts on smaller airfields
Particularly interesting is the explicit inclusion of smaller civil airfields and aerodromes without instrument approach procedures. Previously, large international airports have often been the focus of discussion.
The ICAO now emphasises that even visual flight rules airfields also possess safety-relevant protection interests. Circuit patterns, training operations, safety margins for go-around manoeuvres and local weather effects must also be taken into account.
This could lead to wind power projects in the vicinity of smaller airfields being subjected to more intensive scrutiny in the future.
Significance for general aviation
For general aviation, the new regulations are of considerable significance. Many airfields, flight schools and aero clubs are located in regions that are also attractive for the expansion of wind energy.
The new ICAO guidelines strengthen aviation's position in the assessment of such projects. They create an internationally recognised basis on which safety aspects can be soundly analysed and taken into account in approval procedures.
At the same time, they offer authorities and project developers a clearer framework for balancing energy policy and flight safety.
Conclusion
With the new edition of its Obstacle Manual, ICAO is taking into account the profound changes in both the aviation and energy sectors. Wind turbines will no longer be considered exclusively as high structures in the future, but as complex influencing factors on flight operations.
A greater consideration of turbulence, technical faults, glare effects, and the long-term development potential of airfields is likely to lead to more careful evaluation of construction projects worldwide.
For general aviation, this means a significant step towards greater safety and a stronger consideration of its interests in the planning of major infrastructure projects around airfields.
Source references:
DAEC
