Wake Vortex X-band radar monitoring : Paris-CDG airport ... - WakeNet

Wake Vortex X-band radar monitoring : 

Paris-CDG airport 2008 Campaign 

Results & Perspectives 

Thales Air systems, Strategy Technology & Innovation Dept. 

F. Barbaresco

Short Summary of Wake Vortex 

Radar Campaigns

• USA : 

WAKE VORTEX RADAR CAMPAIGNS 

• During 90’s different Radar trials have been 

made in US for wake vortex monitoring in 

clear Air with positive results for different 

bands. 

Wake Vortex Reflectivity was flat 

as a function of frequency 

DX04 S-band radar 

AN/MPS-39 

C-band radar 

3 

• EUROPE : 

• UK, GEC-MARCONI (1992) : detection at Range 

R = 2.8 Km with an S-band Radar (3 GHz) (DX 

04 Radar Campaign) 

• France, CNRS/CRPE (1992): detection at 

Range R = 0.5 Km with an UHF-band Radar 

(961 MHz) (PROUST Radar campaign) 

Thales Air Systems Division 

Proust UHF Band Radar

CLEAR AIR RADAR REFLECTIVITY OF WAKE VORTEX 

• Tests have revealed radar echoes in clear air. 

• Two mechanisms causing refractive index gradients are : 

• Radial Pressure (and therefore density) gradient in a columnar vortex arising 

from the rotational flow : 

6 ⎛ Pa 

⎞ ⎛ Pv 

⎞ 

5⎛ 

Pv 

⎞ 

(n −1). 

10 = 77. 

6⎜ 

⎟ + 64. 

8⎜ 

⎟ + 3. 

77610 . ⎜ 

2 

⎟ 

⎝ T ⎠ ⎝ T ⎠ ⎝ T ⎠ 

⎧n : refractive index of humid air for frequencies below 20 GHz 

⎪ 

with ⎨Pa 

: the partial pressure (mb) of dry air ; Pv 

: the partial pressure (mb) of water vapour 

⎪ 

⎩T : the temperature (K) , T ∞ 

= 288K 

• Adiabatic transport of atmospheric fluid within a descending oval 

surrounding a vortex pair : 

[ n(z) ~ − n(z) ]. 

with 

• Particulates were not involved (not f 4 Rayleigh scattering) . 

• The frequency dependence was not the Kolmogorov f 1/3 

• The role of Engine Exhaust : 

2 

6 

⎡ 

⎤ 

6 ρ(z)N RH(z)P ⎛ 

⎞ 

sat(Tz 

) 3. 

4910 . 

10 = − Δz⎢223 

+ 

⎜76. 

7 + 

⎟⎥ 

g ⎣ P(z) ⎝ T(z) ⎠⎦ 

⎧N : Brünt-Väisälä Frequency (stratification parameter) 

⎪ 

-1 

−1 

-1 

⎨at Sea Level : N = 0. 

014s 

(in Summer) N = 0. 

02s 

-0. 

03s 

(in W int er) 

⎪ 

⎩Δz : Descend Altitude, and P = Pa 

+ Pv 

• RCS doesn’t change when the engine run at idle or full power 

• Exhaust diameter yields a partial pressure of vapour and a contribution 

which is much smaller than that due to temperature. 

4 

Thales Air Systems Division

Operational Needs for Wake 

Vortex Monitoring

WAKE VORTEX MONITORING IN CRITICAL AREAS 

• Wake Vortex should be monitored In critical Areas (where 

% of occurences is high) : 

• Very Close to the Ground (0 to 400 ft) 

• Glide Path Intercept (3000 to 4000 ft) 

Figures 

From 

NATS 

Voluntary 

Reporting 

6 

Critical Area 2 : 

Glide Path Intercept 

• These Critical Areas should be monitored in All Weather 

conditions (Wet & Dry conditions, Fog, Rain,…) 


Critical Area 1 : 

Very close to the Ground

Wake Vortex Monitoring very close to the Ground 

• Wake Vortex behaviours very close to the 

ground have very complex causes that could 

change abrutly (e.g. Wind Squall or Fall,…) : 

Need for Real Time Monitoring 

• Ground Effect : 

vortices 

Secondary 

vortices 

• Wind Shear : 

• Transport : 

7 


THALES X-BAND RADAR TRIALS

CHARACTERISTICS OF THALES X-BAND BOR-A550 RADAR 

Main Figures 

• Frequency : X Band (9.6 GHz for ORLY Campaign) 

• Minimal Range : 400 m 

• Maximal Range : 40 Km (limited to 2 km for WV) 

• Range Resolution : 40 m 

• Mechanical Tilt : +/- 24° 

• Beam Width (elevation/azimut): 4°/2.7° 

• Radial Velocity Range : +/- 26 m/s 

• Doppler Resolution (& High Resolution) : 0.2 m/s 

(0.04m/s) 

• Mechanical Scan Rate : 8°/s (sur 45° pour ORLY) 

• Peak transmit power: Classified 

• Data Link : RS232 (x2), RS432 (x2), Ethernet 

• Recording System : All range cells 

• external link Ethernet 20 Gb/s 

PRF = 3348 Hz 

F=9.6 GHz 

λ=c/F=3.125 cm 

V amb 

= λ.PRF/2 

V amb 

= 52.31 m/s 

(+/-26 m/s) 

9 


Radar Sensor Campaigns funded by THALES 

• 2006 : Paris Orly Airport (Runway Monitoring) 

Orly 2006 

• From Mode S site (500 m from runway) 

• Wake Vortex Monitoring during departures 

• Weather conditions : Winter (clear air, rain) 

• 2007 : Paris Orly Airport (Glide Path Monitoring) 

• From Thales Limours Testbed Tower 

• Wake Vortex Monitoring during arrivals (Glide Path 

Intercept) 

• Weather Conditions : Autumn (highly turbulent 

atmosphere) 

• 2008 : Paris CDG Airport (CSPR Monitoring) 

• From Kbis Tower co-localized with Eurocontrol Lidar (2 

μm Windtracer) 

• Wake Vortex Monitoring during arrivals/departures on 

Closely Spaced Parallel runways 

• Weather Conditions : Summer (very hot, rain) 

Orly 2007 

CDG 2008 

10 


11 

X-band Radar Sensor for Safety Case & Operational Use 

• Wake Vortex Monitoring in All Weather Conditions (light 

to heavy rain, fog, turbulent atmosphere,…) 

• Operational Use to track Wake Vortex (transport, decay, 

rebound) in extreme weather conditions : 

• Wind burst (wind under Cb, turbulent atmosphere, wind shear…) 

• No Wind (foggy weather,…) 

• Use for « Safety Case » by Data Collection : 


• Risks Assessment according to extreme wind conditions and no 

longer on mean wind conditions 

• Need for Wake Vortex Data in exhaustive cases of airport climatology 

(good/bad weather) 

• Fast Monitoring of very large volume (radar scanning) with 

high update rate (e.g. : 8°/s with mechanical scanning of 

BOR-A radar) 

• Highly sensitivity of Radar : monitoring of Wake Vortex for 

« medium » (high % of A320) aircrafts and not only « heavy / 

super heavy » (requested for traffic mix of « very light jets »)

LIDAR & RADAR WAKE VORTEX DOPPLER SIGNATURE 

LIDAR WAKE VORTEX DETECTION 

Post-processing 

Needed for Wind 

Inversion detection 

Angular 

Radar resolution 

Doppler radar 

signature 

Doppler Lidar 

signature 

12 


ORLY Airport Radar Campaign 2006

Radar (& Lidar Wind Profiler) Site at Paris Orly Airport 

WLS7 Lidar 

Wind Profiler 

14 


THALES 

BORA-550 

Radar

Wake Vortex Detection in All weather Conditions 

No Rain 

Minimum 

Temperature 

8 ° 

Maximum 

Temperature 

14 ° 

Rain Rate 0 mm 

Wind Speed 22 km/h 

Wind Direction : South 

Rain 

Minimum 

Temperature 

Maximum 

Temperature 

Rain Rate 

Wind Speed 

Wind Direction 

9 ° 

12 ° 

1.19 mm 

20 km/h 

South- 

East 

NO RAIN 

RAIN 

RCS of Medium Aircraft Wake Vortex : 0.01 m 2 S/N ≈ 15 dB (Range = 600 m) 

15 


WAKE VORTEX PROFILING : RADAR DOPPLER ANALYSIS 

Spiral 

Geometry 

Tangential Speed 

Versus Radius 

0 m/s 

+/- 

26 m/s 

Cross-Wind Speed 

Speed Variance of 

Rain can measure 

EDR & TKE 

(air turbulence) 

0 m/s 

16 

r 

⎛ = 

bθ 

dr 

1 δ V 

ae ⇒ = br ⇒ b = ⎜ + 

r 

log 1 

dθ 

2π 

⎝ V 


⎞ 

⎟ 

⎠ 

Time (s)

WAKE VORTEX PROFILING : WAKE VORTEX AGE 

Positive 

Time/Doppler 

slopes 

Zero 

Time/Doppler 

slopes 

17 


Low speed 

Negative 

Time/Doppler 

slopes 

Negative 

Time/Doppler 

slopes

Wake Vortex Detection in Clear Air at 7 Km 

7000 m 

Line of sight 

Recording conditions 

• 29 th November '06 

• scanning mode 

• scan angle 45° 

• scan rate 8°/s 

• long transmit pulse 

• distance up to 7 km 

• without rain 

45° 

Wind 

18 


Wake Vortex Circulation Computation 

= k 

3 

.2 nd 

moment 

[ S(V ) ] 2 / 3 

i 

Wake Vortex Doppler Frequencies Extraction 

(Pre-Processing : CFAR on Doppler axis) 

Γ ∝ 

Γ Vmax 

2 

2 V [ S( 

V )] 

V 

∫ 

min 

V 

V 

max 

∫ [ S( 

V ) ] i 

min 

i 

i 

2/3 

2/3 

dV 

dV 

i 

i 

19 


Advanced Processing Chain: 3 Patents 

μ 

N 

2 

* 

∑ f 

n−1 

( k). 

bn− 

1( 

k −1) 

+ 2. 

N − n k = n+ 

1 

= − 

N 

1 

2 

2 

∑ f 

n−1 

( k) 

+ bn− 

1( 

k −1) 

N − n k = n+ 

1 

Regularized Autoregressive 

Burg Algorithm 

(Thales Patent 1) 

n 

n−1 

∑ 

k = 1 

β 

+ 2. 

( n) 

k 

n−1 

∑ 

k = 0 

. a 

β 

( n−1) 

k 

( n) 

k 

. a 

. a 

( n−1) 

n−k 

( n−1) 

2 

k 

Doppler & Image Processing 

For Wake Vortex 

Monitoring & Profiling 


CFAR 

On 

frequency 

d 

2 

with 

(1) (2) 

( θ , θ ) 

δ 

(1,2) 

i 

n 1 

⎛ 1 1+ 

δ 

= ∑ − ( n − i). 

⎜ ln 

i= 

1 ⎝ 2 1−δ 

(1) 

μi 

− μ 

= 

1− 

μ μ 

(1) 

i 

(2) 

i 

(2)* 

i 

(1,2) 

i 

(1,2) 

i 

Doppler Entropy Based on 

Information Geometry 


⎞ 

⎟ 

⎠ 

2 

Radon/Hough 

Γ = γ 

2 

V 

max 

∫ 

V 

. 

V 

min 

[ S( 

V )] 

max 

∫ [ S( 

V ) ] i 

V 

V 

min 

2 

i 

i 

2/3 

2/3 

dV 

dV 

Wake Vortex Circulation 

20 Thales Air Systems Division 

i 

i 

HR Autoregressive Doppler & Entropy 

Implemented in C language : 

3 times faster than real time by 

use of 4 Threads with Quadri-Core PC 

Γ0 

r 

V ( r) 

= ⇒ V ( r) 

= α. 

r 

2π 

. rc 

rc 

⎛ V ⎞ 

r = 

bθ 

1 δ 

ae ⇒ b = ⎜ + 

r 

log 1 ⎟ 

2π 

⎝ V ⎠ 

Wake Vortex Geometry

ORLY Airport / Limours Radar Campaign 2007

Limours (site Thales) : September 2007 

22 


Wake Vortex Monitoring In Glide Path Intercept 

23 

Wake Vortex 

Rollups 


Vertical Scanning 

From Limours Tesbed 

Tower (Orly Glide 

Path Intercept : 

Altitude 1500 m) 

In Highly Turbulent 

Atmosphere !! 

Wake Vortex 

Rollups

CDG Airport Radar Campaign 2008

Radar Sensor Deployment at CDG Airport 

27R 

27L 

Horizontal Scanning 

Vertical 

Scanning 

26R 

08L 

26L 

08R 

25 


Runway WV Detection : West Configuration Procedure 

Wake Vortex Detection based on Doppler Entropy 

Time 

26R 

Departure 

26L 

Arrival 

Range 

West Configuration 

Procedure 

STARING 

ANTENNA 

MODE 

26 


Wake Vortex transport by High cross-Wind 

Time 

Range 

STARING 

ANTENNA 

MODE 

Range 

Cell n-3 

RC m-6 

RC m-5 

Range 

Cell n-2 

Range 

Cell n-1 

RC m-4 

RC m-3 

RC m-2 

Range 

Cell n 

27 


time 

RC m-1 

RC m 

RC m RC m 

time

Wake Vortex transport by Cross-Wind 

28 


Vortex Transport : Doppler Analysis 

RNG 1 to 6 (6 x 40 m = 200 m) 

Time 

rebound 

Range 

29 


Vortex Transport : Doppler Analysis 

RNG 3 and 4 

Time 

Mature Vortex 

Range 

30 


Vertical Scanning : East Configuration Procedure 

Image of High Resolution 

Doppler Entropy 

Wake Vortex Roll-up 

(Arrival) 

31 


Vertical Scanning : East Configuration Procedure 



32 


Vertical Scanning : West configuration 

Wake Vortex Roll-up 

(Departure) 



33 


WV Roll-ups Evolution : West Config. Procedure 

West Config. 

Procedure 

34 



Doppler Entropy



Wake Vortex Roll up 

1rst Runway (Departure) 

2nd Runway (Arrival) 

35 


CDG Radar Campaign Data 

Exploitation

Wake Vortex Position & Circulation (strength in m 2 /s) along runway 

1700 

Position des vortex au cours du temps 

WV roll-ups 

position 

1300 

Position des vortex au cours du temps 

WV roll-ups 

position 

Case distance 

1600 

1500 

1400 

1300 

vortex 1 position 


Case distance 

1200 

1100 

1000 

900 

800 

700 



1200 

1 2 3 4 5 6 7 

600 

1 2 3 4 5 6 

Numéro de balayage 


18 0 

Circulation des vortex au cours du temps en m²/s 

WV roll-ups 

Circulation 

350 

Circulation des vortex au cours du temps en m²/s 

WV roll-ups 

Circulation 

16 0 

300 

14 0 

12 0 

250 

10 0 

80 

vortex1 circulation 


200 

150 



60 

40 

20 

10 0 

50 

0 

1 2 3 4 5 6 7 

0 

1 2 3 4 5 6 


Numéro d e b alayag e 

37 

5 s per scan (35 s) 

Position around 1500 m 

With Cross-Wind 


5 s per scan (30 s) 

Position around 1000 m 

Without Cross-Wind

Occurrences of Wake Vortex Position versus Wind conditions 

38 


Coordination with Eurocontrol & ADP 

• Debriefing meeting has been organized, 18 th of July in 

Eurocontrol Bretigny, with persons in charge of Lidar 

exploitation to : 

• Present first exploitations of radar data records 

• Define File template (date, WV position, WV Circulation) to 

concatenate all results for benchmarking with Lidar 

• Debriefing meeting has been organized with ADP & DSNA , 

25 th of September, with G. Batistella, Guillaume Auquier & Jean 

Jezequel to: 

• Present first results 

• Thank ADP for their logistic support 

• First Excel File has been transmitted to Eurocontrol, the 7 th of 

November & new results in December 

• Exhaustive CDG Trials Exploitation is in progress : 

• Vertical Staring antenna & Vertical Scanning mode 

• Horizontal Scanning 

39 


CONCLUSION

Thales Radar Trials Synthesis 

• Paris ORLY AIRPORT Campaign has proved that X-band Thales 

BOR-A550 Radar can : 

• Detect Wake Vortex (RCS of 0.01 m 2 on medium aircraft) : 

• In all weather conditions (wet & dry at short range < 2 Km) 

• In Staring & Scanning Mode 

• In real Time / Update Rate of 11 s on 90° scan sector 

• Localize Wake Vortex 

• in range/azimuth 

• With resolution : 40 m x 1° 

• Characterize Wake Vortex by : 

• Geometry (Spiral) 

• Age (Young, mature, old, decaying) 

• Strength : Circulation (m 2 /s) 

• Characterize ambient air (in Rain Conditions) 

• Wind (based on Doppler & post-processing) 

• Ambient Air Turbulence (EDR & TKE) 

Medium Aircraft 

Wake Vortex RCS 

0.01 m 2 

(e.g. : Airbus A320) 

X-BAND BOR-A550 RADAR IS AVAILABLE & CAN BE DEPLOYED 

, AS SOON AS 2009, ON LARGE EUROPEAN AIRPORTS 

(Paris CDG, London Heathrow, Francfort, …) for SESAR studies 

41 


Main Objective : Ground wake detection, tracking & alert 

Orly trials 2006 & CDG 2008 

WIMS 

(in TMA) 

Data 

Broadcast 

Approach & Tower 

Controller 

Ground Radar 

Horizontal/Vertical scanning 

of Runways 

Limours trials 2007 

crosswind 

WV Predictor 

Data-Link 

(WV Alerts) 

WV controller HMI 

WV Alarm 

Ground Radar 

Vertical scanning 

of Glide Path Intercept 

crosswind 

Data 

Broadcast 

Pilot 

42 


Complementarities of Radar/Lidar Sensors 

• Radar & Lidar are complementary sensors in all weather operations 

• THALES has proved by derisking campaign (Paris Orly/CDG) that X-band 

Radar & Lidar are complementary for Wake Vortex Monitoring : 

• US Campaign has proved (Westheimer Aiport Campaign) that X-band & 

Lidar are compementary for Wind Monitoring 

43 


Presented at Wakenet USA 2008

Acknowledgements 

ADP (Paris Airport) Radar Team (Orly) 

• Jean-Paul Lecorre 

• Jean-Marc Receveau 

• Daniel Duong 

• Gilbert Herbulot 

DSNA 

• André Simonetti 

• Alfred Harter 

• Jean Jezequel 

Direction des Aires Aéronautiques (ADP CDG) : 

• Gérard Batistella 

• Guillaume Auquier 

Eurocontrol « Wake Vortex » Team : 

• Andrew Harvey 

• Antoine Vidal (visit during Orly 2006 Radar Trials) 

• Vincent Treve (visit during Orly 2007 & CDG 2008 Radar Trials) 

• Jean-Pierre Nicolaon (visit during Orly 2007 Radar Trials) 

44 


Thank you for your attention 

Leonardo Da Vinci

Wake Vortex X-band radar monitoring : Paris-CDG airport ... - WakeNet

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