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European Coordination Action for Aircraft Wake Turbulence

Tags: Air

State of the Art - Background

A flying aircraft generates a turbulent wake as a direct consequence of its aerodynamic lift generation. This wake consists of a high amplitude of swirling air flow velocities concentrated in a region of relatively small spatial extent trailing behind the generator aircraft. Another aircraft entering into this wake may be significantly impacted by the vortex flow.

In order to prevent hazardous wake encounters, minimum separations behind medium and heavy aircraft are maintained by air traffic control and pilots. This allows wakes to decay to non-hazardous levels as they age and are moving out of the flight path of following aircraft.

The International Civil Aviation Organization (ICAO) has defined 'Minimum Wake Turbulence Separations' for worldwide application. These separations are based on three dedicated aircraft classes (Light, Medium and Heavy) depending on aircraft maximum take-off weight. Some regulating national authorities have introduced modified regulations to reflect their specific experience obtained over the years.

Today's wake turbulence separations have basically been established in the 1970s. They are generally regarded as safe since the number of wake encounter incidents by commercial aircraft is very small as long as they are applied. But they are also regarded as overly conservative under many circumstances, for example in conditions of high atmospheric turbulence or strong crosswinds.

Aircraft wake turbulence in general and the associated separations have received increased interest again during the last decade for a number of reasons:

WN3-E Coordination Areas
WN3-E Coordination Areas

- More and more airports are operating at their capacity limit during peak hours, leading to delays and increased fuel burn. Wake turbulence separations are often the limiting factor for runway throughput.

- New aircraft types are entering into service. This includes new and larger aircraft like the Boeing 747-8 and the Airbus A380, but also new aircraft classes like very light jets (VLJ). Furthermore, the fleet mixes themselves are changing with some airports experiencing increased variety in aircraft sizes.

- Traffic density is increasing in general, leading to more and more aircraft operating in close vicinity to each other and thus potentially increasing the risk from wake encounters.

- New technologies are emerging and entering into operation. Increased information sharing, new and more capable sensors, new decision making tools and higher automation allow for new solutions to address wake encounter risk.

Many different research and development activities have been launched in response to these needs and opportunities and in order to safely reduce wake turbulence separations. They address a wide and complex range of related topics, including the following:

- New operational concepts;

- Regulatory framework and means of compliance;

- Improved understanding and characterisation of aircraft wake vortices;

- Probabilistic prediction of wake vortex behaviour;

- Safety assessments of wake encounters by flight tests and simulation;

- Probabilistic modelling of wake encounters;

- Weather prediction, monitoring and statistics;

- Wake encounter incident reporting;

- Automated analysis of flight data recordings for wake encounters;

- Real-time detection, monitoring and characterisation of aircraft wakes by ground-based and airborne sensors;

- Wake vortex advisory systems;

- Wake vortex alleviation at the source;

- Airborne wake encounter avoidance & alleviation systems;

In line with the large number of related topics, many stakeholders are concerned.


The main objectives of WakeNet3-Europe are:

- To be a forum promoting multidisciplinary exchange between specialists active in the field of aircraft wake turbulence and to disseminate relevant information;

- to develop a shared view on how to address safety and capacity related issues caused by wake turbulence;

- to give recommendations, which are agreed between all relevant stakeholders from R&T and operations, on how to support new operational concepts, procedures and new regulations relative to wake vortex;

- to help making new technologies usable for operational purposes;

- and to give recommendations for future research, in order to support operational users' needs.

Description of Work

WakeNet3-Europe is composed of 12 beneficiaries plus third party, Eurocontrol. They represent all major related disciplines.

The project is structured according to three coordination areas (Technologies, Safety and Concepts) with second level task groups addressing specific topics plus dedicated links to existing local stakeholder groups, professional groups and other projects as well as to US and other non-EU activities (e.g. WakeNet USA and WakeNet Russia).

WakeNet3-Europe provides annual workshops open to the whole wake vortex community, promoting global information exchange and networking.

In addition, specific workshops addressing key topics with experts and stakeholders are organised.

Based on these activities the members of WakeNet3-Europe establish recommendations for future wake vortex research in Europe and for the implementation of the solutions developed for operational schemes, as well as of adapted regulations.

Results are communicated to the public via the project's internet site accessible at

Expected Results

WakeNet3-Europe will contribute to achieving the ACARE goals and FP7 objectives by fostering multi-disciplinary information exchange and harmonized approaches on topics related to aircraft wake turbulence through dedicated means like public and specialists workshops, research needs reports, and position papers.

It is directly contributing to establishing new solutions allowing to safely reduce separation distances between aircraft, which in turn enables a reduction of delays as well as an increase in capacity together with the associated societal benefits.