The performance and ATC integration of DLR's wake vortex advisory system "WSVBS" (Wirbelschleppen-Vorhersage-und-Beobachtungssystem) for the dependent parallel runway system 25L and 25R at Frankfurt Airport are described. WSVBS has components to forecast and monitor the local weather and to predict and monitor wake transport and decay along the glide paths. It is integrated in the arrival manager AMAN of DLR. Each 10 minutes it delivers minimum safe aircraft separation times for the next hour to air traffic control. These times are translated into operational modes for runways 25L/R aiming at improving the capacity. From 66 days of a performance test at Frankfurt it was found that the system ran stable and the predicted minimum separation times were safe. The capacity improving concepts of operation could have been used in 75% of the time and continuously applied for at least several tens of minutes. From fast-time simulations the eventual capacity gain for Frankfurt was estimated to be 3% taking into account the real traffic mix and operational constraints in the period of one month.

Design and performance of the Wake Vortex Prediction and Monitoring System WSVBS are described. The WSVBS has been developed to tactically increase airport capacity for approach and landing on single runways as well as closely-spaced parallel runways. It is thought to dynamically adjust aircraft separations dependent on weather conditions and the resulting wake vortex behavior without compro-mis>ing safety. Dedicated meteorological instrumentation and short-term numerical terminal weather prediction provide the input to the prediction of wake-vortex behavior and respective safety areas. LIDAR monitors the correctness of WSVBS predictions in the most critical gates at low altitude. The WSVBS is integrated in the arrival manager AMAN of DLR. Performance tests of the WSVBS have been accomplished at Frankfurt airport in winter 2006/07 and at Munich Airport in summer 2010. Aircraft separations for landings on single runways have been compared employing the concepts of either heavy-medium weight class combinations or dynamic pairwise separations where individual aircraft type pairings are considered. For the very conservative baseline setup of the WSVBS the potential capacity gains of dynamic pairwise operations for single runways appear to be very small. On the other hand, the consideration of individual aircraft types and their respective wake characteristics may almost double the fraction of time when radar separation could be applied.

S u MMARYA three-layer shallow-water numerical model is used to study the motion of tropical-cyclone-like vortices in a westerly baroclinic current. The structure of the vortex and its environment are chosen to be representative of real tropical cyclones. Numerical experiments with and without convection are discussed. Several different environmental flows are considered.In calculations on a northem-hemisphere f-plane without convection, anomalies of upper-layer potential vorticity (PV) have a major influence on the vortex motion in the middle layer. This is true even in numerical experiments that include a PV-gradient in the middle layer associated with an upper-level westerly jet. For example, when a broad anticyclone is included in the upper layer, the middle-layer vortex moves initially to the east-northeast. If the middle-layer PV-gradient were the dominant factor, the middle-layer vortex would, instead, move to the south-east. When there is no middle-layer PV-gradient, the middle-layer vortex is deflected to the right of the environmental shear vector if the upper-layer vortex is cyclonic and to the left of the environmental shear vector if the upper-layer vortex is anticyclonic. The size of the vortex affects the drift velocity, but has a negligible effect on the drift direction.Calculations incorporating a convective parametrization based on that developed by Ooyama (1969) show that an initially weak vortex can intensify to hurricane strength in a conditionally neutral environment. This calculation underscores the importance of surface fluxes in Ooyama's scheme and subsequent schemes based on it, as it shows that the scheme does not rely necessarily on a large amount of convective instability in the initial state.In calculations on a northern-hemisphere f-plane with an upper-level westerly jet and convection, the middlelayer vortex moves to the south-east because of the middle-layer PV-gradient. When the middle-layer PV-gradient is removed but the convection retained, the middle-layer vortex moves first to the south-east and then to the northeast. In this case the motion of the middle-layer vortex is controlled by the upper-layer PV-anomaly. At early times, the vertical shear tilts the vortex towards the east so that the western side of the upper-layer cyclonic core lies above the middle-layer vortex centre. Consequently, the upper-layer cyclonic core induces a southward component to the flow across the middle-layer vortex centre. As time proceeds, the upper-layer westerlies advect the broad anticyclonic outer part of the upper vortex over the middle-layer vortex centre, inducing a northward component across its centre.Relatively minor changes to the convective parametrization have a relatively large effect on the motion of the vortex. Changing the way the parametrized clouds transport momentum, changes the structure of the upper-layer vortex. Changes to the pattern of PV in the upper layer in turn affect the middle-layer flow attributable to it. The effect of the upper-layer PV on the motion of the middl...

During two field measurement campaigns aircraft wake vortex trajectory and wind measurement data have been collected at Frankfurt airport. Three different approaches have been used to analyse the data in order to estimate crosswind threshold values supporting vortex-free corridors for departing aircraft. Although several competing effects such as wake vortex transport in and out of ground effect, temporal and spatial wind variability, and the spreading of aircraft trajectories after take-off, complicate the analyses, all three approaches lead to similar crosswind thresholds. Employing standard instrumentation at 10 m, a minimum crosswind threshold of 3.5-4.6 m s −1 has been identified to clear a safety corridor of 150 m width from wake vortices with a 95% probability within 60 s. Alternative estimations of crosswind thresholds employing different instrumentation and different height ranges are reported. Crosswind thresholds can be reduced if the wind is measured close to the air mass in which the vortices evolve. A definite crosswind threshold for operational use cannot be deduced solely from this study since critical factors such as risk and safety assessment have not yet been taken into account.

No abstract