Optimising Runway Throughput through Wake Vortex Detection, Prediction and decision support tools Frédéric Barbaresco, Philippe Juge, Mathieu Klein , Yves Ricci & Jean-Yves Schneider, Surface Radar, Advanced Developments Department Thales Air Systems, Limours, France frederic.barbaresco@thalesgroup.com Jean-François Moneuse FASNET Team Manager Air Traffic Management Systems Thales Air Systems, Rungis, France Jean-françois.moneuse@thalesgroup.com Abstract— Currently at many airports, runway is the limiting factor for the overall throughput. Among the most important parameters are the fixed wake turbulence separation minima expressed in time for take-off clearance and by distance for arrivals on final approach. This wake turbulence separation limits the arrival and departure flow on many airports in Europe already today. Existing departure and arrival wake turbulence separations are sometimes considered over conservative as they do not take into account meteorological conditions likely to shift, reduce or alleviate their circulations. This paper will present the main aspects of a SESAR project that defines, analyses and develops a verified wake turbulence system according to related operational concept improvements in order to, punctually or permanently, reduce landing and departure wake turbulence separations and, therefore, to increase the runway throughput in such a way that it safely absorbs arrival demand peaks and/or reduces departure delays. This global objective will be achieved by means of developing a wake vortex decision support system able to deliver in real time position and strength of the wake vortices and to predict their behavior and potential impact on safety and capacity, taking in account actual weather information as well as the airport specific climatological conditions, aircraft characteristics (generated wake vortex and wake vortex sensitivity) and airport runways layout. These functionalities will be progressively included in the wake vortex decision support system to be validated and deployed on airports in order to optimize the runway throughput and reduce delays. Keywords- airport, wake-vortex, safety, radar, lidar I. INTRODUCTION Aircraft creates wake vortices in different flying phases. To avoid jeopardizing flight safety by wake vortices encounters, time/distance separations have been conservatively increased, thus restricting runway capacity. The concern is higher during taking off and landing phases, as aircraft are less easy to maneuver. These vortices usually dissipate quickly (decay due to air turbulence or transport by cross-wind), but most airports operate for the safest scenario, which means the interval between aircraft taking off or landing often amounts to several minutes. However, with the aid of accurate wind data and precise measurements of Wake Vortex, more efficient intervals can be set, particularly when weather conditions are stable. Depending on traffic volume, these adjustments can generate capacity gains, which have major commercial benefits. Wake vortices are a natural by-product of lift generated by aircraft and can be considered as two horizontal tornados trailing behind the aircraft. A trailing aircraft exposed to the wake vortex turbulence of a lead aircraft can experience an induced roll moment (bank angle) that is not easily corrected by the pilot or the autopilot. However these distances can be safely reduced with the aid of smart planning techniques of future Wake Vortex Decision Support Systems based on Wake Vortex detection/monitoring and Wake Vortex Prediction (mainly transport estimation by cross-wind), significantly increasing airport capacity. This limiting factor will be significantly accentuated soon with the arrival of new heavy aircrafts: Airbus A380, stretched version of Boeing B747-8. Radar and Lidar Sensors are low cost technologies with highly performing complementary wake-vortex detection capability in all weather conditions compared to others sensors that suffer of limited one. Radar and Lidar are promising sensors for turbulences remote sensing on airport, for all kinds of aviation weather hazards (wake vortex, wind-shear, micro- bursts, atmospheric turbulences) with ability to work operationally in a collaborative way, in different severe weather conditions like fog, rain, wind, and dry air. II. WAKE VORTEX HAZARDS The Wake Vortices shed by an aircraft are a natural consequence of its lift. The wake flow behind an aircraft can be described by near field and far field characteristics. In the near field small vortices emerge from that vortex sheet at the wing tips and at the edges of the landing flaps. After roll-up the wake generally consists of two coherent counter-rotating swirling flows, like horizontal tornadoes, of about equal strength: the aircraft wake vortices. Empirical laws model tangential speed in roll-up. Classically, velocity profile (tangential speed at radius r) is defined by :                   B r f e r r v 1 2 ) ( 0   (1)