Das Institut für Physik der Atmosphäre

1. Das Institut für Physik der Atmosphäre Climate-Chemistry Models Noise Trace gases N-oxides Aerosoles Radiation Transfer Satellite-algorithms Radar-systems Clous physics Wake vortices Traces and Wind-Lidar tunable Laser

2. Research towards a Wake-Vortex Advisory System for Optimal Aircraft Spacing Thomas Gerz, M. Frech, F. Holzäpfel, F. Köpp, A. Tafferner Institut für Physik der Atmosphäre Deutsches Zentrum für Luft- und Raumfahrt / German Aerospace Center (DLR) Oberpfaffenhofen Thomas.Gerz@dlr.de

3. What are aircraft wake vortices (WV) ? Why and to whom are they a problem ? Impact of the atmosphere on transport and decay of WV Solutions at the aircraft: Measures to minimise the life-time of WV Solutions for the airport: Concept of prediction and observation Results are presented from projects co-funded by EU: C-Wake, S-Wake, AWIATOR, ATC-Wake DLR project Wirbelschleppe (1999-2002, 2003-2006) ONERA-DLR collaborative research programme Minimised Wake S-WAKE Assessment of Wake Vortex Safety Outline C-Wake AWIATOR

4. Approach of a B 747 to the old Hongkong Int‘l Airport Who should care about wake vortices ?

5. Who should care about wake vortices ? Incidents and accidents in civil aviation: all reasons loss of control from: Aviation Week, August 26, 2002, p.50

6. Who should care about wake vortices ? ICAO wake vortex separation standards from C-Wake Technical Annex extra separations due to wake vortex uncertainties

7. Who should care about wake vortices ? • Wake vortices today are a capacityproblem for • airports • safety providers • airlines • Wake vortices increasingly become a safety problem for • pilots • passengers • residents

8. San Francisco Int‘l Airport Who should care about wake vortices ? Flughafen Frankfurt am Main 25L 25R 1700 ft

9. Atmospheric impact: What do we know ? • Trajectories and life time of aircraft wake vortices are determined by • cross wind • turbulence • wind shear • thermal stratification • contact with ground • The list is approximately ranked according to the ability to transport the vortices • out of the safety corridor or to destroy the vortices. • It is necessary to predict and monitor these meteorological • parameters and the resulting wake vortex behaviour around • an aerodrome at the scales of the wake vortices

10. Lateral Transport  crosswind > 2 m/s, Memphis, S-Wake 100% 100% 0% 1% 0% 0% 0% 0% +/-30 m +/-50 m 2.5 nm H->H 4 nm M->H 5 nm Safety corridor (+/- 30 m) 251 vortices (only OGE) Journal of Aircraft

11. Atmospheric impact: consequences for vortex circulation Holzäpfel et al., AST, 2001

12. standard weather forecast and observation Weather Monitoring (air / ground) 4d synoptic-scale predicted data statistics evaluations Check nowcast / data assimilation Weather Nowcasting Wake Monitoring (air / ground) (z,t) - profiles of wind, turbulence, and temperature along glide path Vortex strength / posi- tion along glide path Wake Prediction concept/procedure requirements Assessments Probability, Safety, Reliability ATC aircraft data aircraft spacing ATC Konzept eines Systems zur Vorhersage undBeobachtung von Wirbelschleppen

13. Weather Nowcasting: model chain with nesting LM forecasting domain MM5 forecasting domain 2 MM5 forecasting domain 1 Wake Vortex Prediction Cross section along glideslope Airport area

14. Weather Monitoring: Sensors used in the field trials U,,Tv,σw LIDAR SODAR/RASS uLOS sonic anemometer (20 Hz) u,v,w,Tv

15. onset of rapid decay diffusion rapid decay respective decay rate Wake Prediction: WV transport and decay model - P2P, Probabilistic 2-Phase model (F. Holzäpfel) diffusion phase = f (*, N*) rapid decay

16. P2P - wake transport and decay predictions and comparison with LIDAR data Flugzeugparameter und Meteorol. Profile als Eingabe Lateral displacement Circulation Vertical displacement

17. Display of a wake prediction along the glide path - MOPS (D. Joos)

18. ILS approach path • area of height • and lateral deviations • approach • corridor • over all • hazard zone • (penetration prohibited) • P2P prediction • t = t • outer boundary of wake vortex area • hazard zone of a single wake vortex for • * < 0.3 Bestimmung des WS-freien Korridors (K.-U. Hahn, Flugsystemtechnik DLR Braunschweig) • t = 0 * = mögliches Rollkontrollmoment

19. Wake Monitoring

20. LIDAR - (cross-) wind und wake vortex measurements: Sequence of LOS velocity signatures of LTA vortices 13. 06. 2002, 18:35 - 20:06 UTC, cross wind: 3 - 6 m/s (F.Köpp, I.Smalikho) 0 Height 500 m 0 Lateral Distance 1300 m

21. Wake-vortex characterisation by 2 µm pulsed lidarOver-flight 4-22  Trajectories of the vortex pair Time dependence of core separation, tilt angle and vortex circulation  open circles: port vortex, full circles: starboard vortex

22. Oberpfaffenhofen2001 C-Wake: WakeOP 2001WakeTOUL 2002AWIATOR: FT1 2003Three campaigns to predict and measure wake vorticesand the respective weather Tarbes 20022003 Pyrenees

23. SODAR - NOWVIV comparison for 14 June 2002: wind speed (m/s) Simulation Observation phase error 18:30 17:00

24. NOWVIV: 1-hour cycle of assimilation/nowcasting system (currently 12 hour cycle) A. Tafferner, L. Birke, M. Frech, H. Volkert LM (t) LM (t+1h) LM (t+2h) LM (t+3h) Data Data Data Time real time old forecast new forecast O U T P U T Boundary plus assimilated data Boundary data from LM Nudging of local data over prescribed time window

25. Conclusions • Transport and decay of aircraft wake vortices in the atmosphere is understood. • Consensus has been achieved that predicting the wake evolution requires probabilistic • approaches in order to account for the stochastic nature of the atmospheric processes • at the temporal and spatial scales of the aircraft wakes, in particular in turbulent • environments and for the complex interaction of vortices with wind-shear layers. • The components for prediction, observation, and safety assessment, NOWVIV, P2P, • VFS, SHAPe, WAVIR, pulsed LIDAR, and RADAR/SODAR/RASS combinations, • constitute the corner stones of the European Wake Vortex Prediction and Monitoring • System (WVPMS) which is suited to fulfil the operational requirements of modern • air-traffic control and management to safely optimise aircraft separations.

26. Conclusions, cont' d • The experience gathered during several field trials has shown that a pulsed Doppler • LIDAR is the most promising tool for monitoring the approach and departure corridors • at airfields with respect to wake vortices and cross-wind profiles. • RADAR/SODAR/RASS may be seen as a robust instrument combination which can • be used in an operational environment on an airport site. Ideally, both types of • instruments should be available for operational purposes. • Meteorological information along the glide path is only available from NOWVIV forecasts. • These forecasts as well as wind data collected by the aircraft along its flight track in • WakeOP attest the substantial variability of wind along the glide path, e.g., due to land • surface heterogeneity. Therefore, in the future also the meteorological data collected • by commercial aircraft (like AMDAR) will be integrated into the WVPMS. • Finally, a dual-Doppler or bistatic weather RADAR surveying the larger-scale wind • field in the terminal area will contribute to increase the system performance.

27. Conclusions, cont' d • The forecast cycle of the weather forecasting model of the Deutscher Wetterdienst, • DWD, will be shortened to three hours by the end of 2005, that is, boundary values • for NOWVIV would then be updated every three instead of twelve hours. This should • noticeably improve the forecast quality as weather events approaching the NOWVIV • domain are easier to recognise and the flow field in the NOWVIV area is in better • balance with the external forcing. The forecast quality should further improve when • a new version of NOWVIV, currently under development, will assimilate observation • data from RADAR and AMDAR into the model runs. • DLR prepares a three months forecast and observation campaign 2006 at Frankfurt Airport • where the entire WVPMS including an off-line ATC environment will be tested. It is • currently planned to broaden this campaign with German and European partners in • order to address also aircraft separations for departures and aviation meteorology • issues in general. The goal is to initiate an European Integrated Terminal Weather System.