WV SEPARATIONS TECHNOLOGY CASE

Transcription

1 WV SEPARATIONS TECHNOLOGY CASE Preparation of Wake Vortex Detection Technology Case Eurocontrol EEC TRSC52/2004 Public Summary Report L.Sauvage 1, E.Isambert 2, G.Winckelmans 3, J.P.Cariou 4, A.Dolfi 4 1. Leosphere, Paris, France 2. M3Systems, Toulouse, France 3. Université catholique de Louvain, Belgique 4. ONERA, Palaiseau, France Version 1.1 (March 05)

2 LEOSPHERE, 134 av. parmentier, Paris, France Phone number: +33 (0) Fax number: +33 (0) lnfo@leosphere.fr Home page: M3 Systems 1, rue des Oiseaux, Lavernose, France Phone number: +33 (0) Fax number: +33 (0) info@m3systems.net Home page: ONERA /DOTA Chemin de la Hunière F Palaiseau, cedex, France Phone number: Fax number: Home page: Department of Mechanical Engineering, Unité de Thermodynamique, Place du Levant, Louvain-la-Neuve BELGIUM Phone number: ( Office ) or ( Secretary ) Fax number: gsw@term.ucl.ac.be EEC/ TRS-C52 - Final report -ii- restricted

3 Edition history Edition Date and Author(s) Reason Nº Status /03/2005 L. Sauvage Contract Deliverable /03/2005 A. Harvey Modifications for distribution to WakeNet Important notice: This report belongs exclusively to Eurocontrol. Its use and diffusion remain the responsibility of Eurocontrol. Any copy or quotation of the document or any of its parts (including by the document's authors) requires prior agreement from Eurocontrol. This report's recommendations are the result of a thorough analysis conducted by various experts specialized in ATC, atmospheric remote-sensing tools and statistical atmospheric modelling. These competences have been gathered together with the aim of achieving the most objective and complete understanding possible of user needs and of the technological scenarios required to satisfy them. The study was based on a methodology validated by Eurocontrol, which included joint working sessions, the reading of recent scientific articles and commercial brochures, and in-depth interviews with scientific and industrial experts. However, it is vital to highlight that the results obtained are not definitive. The preliminary recommendations concerning functional specifications and technological orientations require a further process of detailed validation in the field. The only objective of this study is to help Eurocontrol prioritise validation tests for an operational concept in the context of a wider project of separation standards development. The use of trademarks or names of manufacturers or laboratories in this report is made for accurate reporting only and does not constitute an official endorsement in any kind of the products or manufacturers by the authors or the owner of the study. EEC/ TRS-C52 - Final report -iii- restricted

4 Table of Contents 1 IDENTIFICATION OF WAKE VORTEX MEASUREMENT REQUIREMENTS INTERCEPTION OF ILS GLIDE SLOPE AND FINAL APPROACH LANDING BELOW 400 FT TAKE-OFF BELOW 400 FT INITIAL CLIMB PHASE FROM 400 FT TO 3000 FT APPLICATION OF REDUCED SEPARATIONS WV MEASUREMENT PARAMETERS Required Measurements for the prediction of WV evolution ASSESSMENT CRITERIA OF DETECTION TECHNOLOGY SENSOR PERFORMANCE CRITERIA Atmospheric parameters Measurement protocol Specific Requirements for Scanning Sensors (LIDAR, RADAR) OTHER GENERAL CRITERIA OVERVIEW OF CANDIDATE TECHNOLOGIES IN-SITU TECHNOLOGIES REMOTE SENSING TECHNOLOGIES Detection of wind profiles and wake vortex in Critical areas Wind profiles on the glide slope Temperature and Turbulence measurement CRITICAL ASSESSMENT OF THE CANDIDATE TECHNOLOGIES ASSESSMENT METHOD CRITICAL ANALYSIS OF THE SENSORS Conformity to Performance Criteria Technology for WV detection Impact of measurement protocol Impact of weather conditions Weather conditions classification RECOMMENDED TECHNICAL SOLUTIONS INTRODUCTION REFINED FUNCTIONAL SPECIFICATIONS ORIENTATION FOR TECHNOLOGY CASE Short term Optimal Operational solution Short-Term Low Cost Operational Solution Mid-term solution Preparatory work Validate a Common-core Solution Adapted Common-core Scenario for Major Airports REFERENCES REPORTS: PAPERS AND ORAL COMMUNICATIONS: APPENDIXES ASSESSMENT GRID FOR REMOTE SENSORS TECHNOLOGICAL ASSESSMENT AGAINST DETECTION CAPABILITIES AND AREAS TO REACH EEC/ TRS-C52 - Final report -iv- restricted

5 List of Frequently Used Symbols ABL ACC AGL AMAN APP ATCO ATIS ATSU AVOL CETP COTS CSPR DEP DGPS DMAN DME EAT EDR ETA FAF FDPS FIR GND HALS / DTOP HKIA HMI IAF IAS IGE ILS IMC INI ITM LDA LIDAR LOS LVP MAP MIRS MLS MTOW NDB NGE NTZ P2P PAM PRM P-VFS RADAR RWY SMR SODAR SOIA STAR TDWR Atmospheric Boundary Layer Air Traffic Control Centre (en route) Altitude above Ground Level Arrival Manager Approach ATC Unit Air Traffic Control Officer Air Traffic Information Service Air Traffic Service Unit Airport Visibility Operational Level Centre Etude des systèmes Terreste et Planétaires Commercial off-the-shelf Closely Spaced Parallel Runways Departure Differential Global Positioning System Departure MANAGER Distance Measuring Equipment Expected Approach Time Eddy Dissipation Rate Estimated Time of Arrival Final Approach Fix Flight Data Processing System Flight Information Region Ground Controller High Approach Landing System / Dual Threshold Operations Hong Kong International Airport Human Man Interface Initial Approach Fix Indicated Air Speed In-Ground Effect Instrument Landing System Instrument Meteorological Conditions Initial Approach Controller Intermediate Approach Controller Localizer Directional Aid Light Detection and Ranging Line of Site Low Visibility Procedure Missed Approach Point Microwave Remote Sensing Laboratory Micro Wave Landing System Maximum Take-Off Weight Non-Directional Beacon Near-Ground Effect Non Transgression Zone Probabilistic Two-Phase wake vortex transport and decay model Precision Approach Monitoring Precision Radar Monitor Probabilistic use of VFS Radiation Detection and Ranging Runway Surface Movement Radar Sound Detection and Ranging Simultaneous Offset Instrument Approaches Standard Arrival Route Terminal Doppler Wind RADAR EEC/ TRS-C52 - Final report -v- restricted

6 TEP THR TKE TMA TWR VFS WP WSWS WV PMS WV Turbulent Eddies Profiler Runway Threshold Turbulent Kinetic Energy Terminal Manoeuvring Area Tower Controller Vortex Forecast System Work Package Wirbelschleppen-Warnsystem Wake Vortex Prediction and Monitoring System Wake Vortex List of Figures Figure 1: Critical Areas for ILS Interception, Final Approach and Landing... 2 Figure 2: Critical Areas for Take-Off and Initial Climb... 3 Figure 3: Measurement protocol for critical arrival areas (ILS Interception, Final Approach and Landing)... 8 Figure 4: Measurement protocol for critical departure areas (Take-Off and Initial Climb) Figure 5: Maximum LIDAR range vs. visibility... 9 List of Tables Table 1: System ranges... 6 Table 2: Detailed list of functional parameters deduced from users needs Table 3: Overview of candidate technologies Table 4: Remote sensors classification vs. functional parameters and limiting atmospheric conditions. COTS and mature R&D remote sensors have been assessed Table 5 : Ideal short term operational package Table 6 : Substitute package for a middle term solution Table 7: Assessment grid for remote sensors Table 8: Technological assessment against detection capabilities and areas to reach EEC/ TRS-C52 - Final report -vi- restricted

7 Part 1 1 Identification of Wake Vortex Measurement Requirements The objective of the Eurocontrol project WAKESEP is to propose extensions to the current ICAO separations with a set of separations based on an understanding of wake vortex behaviour under different atmospheric conditions. For ATC operations, four critical areas with respect to Wake Vortex (WV) encounter risk (2 areas for arrivals, 2 areas for departures) have been defined. 1.1 Interception of ILS Glide Slope and Final Approach The intermediate approach phase covers the preparation for the interception of the landing aid (ILS) and is under the responsibility of an Approach Controller. The separation between aircraft has to be maintained throughout the final approach. As the aircraft fly at low speed (decreasing) during the final approach, the spacing applied by the Approach Controller aims at obtaining the prescribed separation at the runway threshold (compression effect). Any loss of separation means that the follower (subsequent) aircraft has to abort the approach (missed approach). In cases where the aircraft spacing is not compliant with the prescribed separation, the Approach Controller will request that the next aircraft makes a holding manoeuvre (e.g. heading instructions). Currently the Approach Controller has no information relating to the wake vortex of individual aircraft. The typical area corresponding to ILS glide slope covers a volume of airspace of about 13.6 NM length or 4000 ft height. See Figure 1. For reduced WV separations the system shall determine for every arriving aircraft during the ILS interception and during the final approach whether this aircraft will penetrate within a predefined time period (time ahead) a wake vortex potential encounter area called WV danger area. 1.2 Landing Below 400 ft The area around runway threshold below 400 ft represents an area where aircraft are particularly vulnerable to wake vortex or wind shear (low speed-low altitude).the Tower Controller is responsible to "protect" the glide slope and the runway for the aircraft on approach (e.g. prevent runway incursion) and to inform the Pilot about any unforeseen safety hazard (e.g. obstacle). In case of any loss of aircraft separation or unforeseen hazards during the final approach, the Pilot executes a go-around and follows the missed approach procedure. Currently the Tower Controller has no information relating to the wake vortex of individual aircraft. The area corresponding to the landing phase is a volume centred around the ILS glide slope, the base of which is the surface of the touch-down area on the runway (about m from runway threshold). See Figure 1. For reduced WV separations the system shall detect (and predict) the presence or absence of wake vortices in the critical area for landing phase, in particular from when the area is crossed by an aircraft until the entry of the next consecutive aircraft. The interaction of the vortices with the ground (In Ground Effect) is complex and can increase of decrease the duration of the vortex depending on the atmospheric conditions EEC/ TRS-C52 - Final report -1- restricted

8 Wind Final Approach Fix (FAF) ILS Glide Slope Runway 3000 m / 60 m (typically) Threshold ILS Interception Area Final Approach Altitude between 2000 and 6000 ft (typically) ILS Glide Slope : 3 (5.2%) 4 Max course deviation : 2 Ie horizontal deviation at FAF : +/- 800m Landing H = 400 ft 2500 m 400 m m (3 NM) m (13.6 NM) Touch-Down Area Figure 1: Critical Areas for ILS Interception, Final Approach and Landing 1.3 Take-Off Below 400 ft The take-off movements are under the responsibility of the Tower Controller. He is in charge of applying the pre-defined time separation between consecutive aircraft (e.g. ICAO standard separation: 2 min between 2 medium aircraft), and to protect the rolling aircraft from any unforeseen hazards such as runway incursion. In case of any unforeseen hazard, the Tower Controller may order the aircraft to abort take-off (if aircraft speed is below the go/no go decision speed V1 ) or informs the pilot about the hazard and lets him take the appropriate decision. In contrast to final approach and landing, the aircraft trajectories for take-off vary significantly (rotation point, climb rate) and these differences depend on a number of factors (aircraft weight, pilot preferences, etc.) that are not known by the ATC system. Below 400 ft typically, the trajectory corresponds to a straight climb (no manoeuvre). The area which encompasses take-off movements below 400 ft is wider than the one for landings, it represents a volume, the base surface of which corresponds to approximately half a runway (typically 1500m) and is delimited by minimum (5%) / maximum (15%) climb rates. See Figure 2 When reduced WV separations are used the system shall detect (and predict) the presence or absence of wake vortices in the critical area for take-off phase, in particular from when the area is crossed by an aircraft until the entry of the next consecutive aircraft. As for the landing phase, the In Ground Effect can be significant EEC/ TRS-C52 - Final report -2- restricted

9 1.4 Initial Climb Phase from 400 ft to 3000 ft The initial climb phase is first under the responsibility of the Tower Controller. The initial climb phase is executed following the Standard Instrument Departure (SID) procedure, which leads the aircraft to its selected airway. The aircraft climb to the cleared flight level may include several steps (level-off) as instructed by the Controller. The Tower Controller or the Approach Controller is in charge of maintaining the appropriate spacing between aircraft (between consecutive departures and for crossing with other aircraft). The concerned area is defined similarly as the one for take-off, it covers up to the altitude of 3000 ft but its width is larger (e.g. aircraft first turn at 1000ft). See Figure 2 During the climb phase (below 3000ft), the system shall determine whether the aircraft will penetrate within a predefined time period (time ahead) a wake vortex potential encounter area called WV Danger Area. Wind Runway 3000 m / 60 m (typically) Width : dependent on standard instrument departure (SID) Threshold Max Climb Rate : 15% H = 3000 ft Take-off H = 400 ft Initial Climb Min Climb Rate : 5% 1500 m 2400 m 700 m m (9.7 NM) Figure 2: Critical Areas for Take-Off and Initial Climb 1.5 Application of Reduced Separations The minimum applicable aircraft separation for landing traffic is related to the runway acceptance rate and to the performance of surveillance equipment. Under favourable wake vortex conditions, a separation of 2.5 NM at threshold for aircraft flying on the same final approach path is a potential target. For departures, a separation of 60 s between aircraft on the same runway is also a potential target, provided that WV transport out of the runway area is confirmed by detection. Case of Cross Wind In the case of established (sustained) cross wind, there is lateral transport of the wake vortices out of the ILS glide slope corridor. Case of Strong Head Wind In the case of established (sustained) head wind, there is longitudinal transport of the wake vortices. If the wind is strong enough, the vortices are blown out of the glide slope corridor. Headwinds are usually associated with increased levels of turbulence (see below). EEC/ TRS-C52 - Final report -3- restricted

10 Turbulence Effect The amplitude of rapid wind fluctuations (turbulence intensity) is an important factor in determining the decay of the rotational speed of vortices. In the event of weak and moderate turbulence the vortices can be long-lived. Strong turbulence causes a significant perturbation in the vortices even from the heaviest aircraft; it induces a rapid decay independent of the average wind direction or speed. Stratification Effect If the wake is generated and sinks in a stably stratified atmosphere, the stratification effect will accelerate the circulation decay and reduce the vortex vertical velocity. An unstably stratified atmosphere results in strong turbulent updrafts (thermals) and downdrafts. 1.6 WV Measurement Parameters The detection and monitoring of WV means that the following parameters must be obtained: The position of each vortex (position of the centre in the measuring plane) The circulation of each vortex The term WV detection corresponds mainly to the provision of snapshots of one or two vortices in a 2D plane which comprises the position of each vortex and their circulation (referred to as Gamma_5_15). WV detection is to be performed for all aircraft in approach or taking-off from a single runway or 2 parallel runways. The detection is performed by dedicated remote sensors that are addressed in Part 2 of this document. The detection of wake vortex typically requires measurement of meteorological parameters, such as: wind profile: assessment of WV transport, decision criteria for the application of reduced separation turbulence profile (or single measurement at low height): assessment of turbulence effect on wake vortex decay temperature profile: assessment of stratification effect (stable or unstable) on WV transport and decay visibility and base of clouds (always monitored by airports) Required Measurements for the prediction of WV evolution In summary, the measurements shall be: Position (time stamped) and velocity of leader aircraft (eventually with precision monitoring) Short-term trajectory of the follower (subsequent) aircraft Weight of leader aircraft (estimated if not available using safety margins) Wind profiles Temperature profiles (possibly) Turbulence (possibly): tke and/or edr Position of each WV (direct, by LIDAR and wind line, and/or indirect, by prediction) Circulation of each WV (direct, by LIDAR, and/or indirect, by prediction) EEC/ TRS-C52 - Final report -4- restricted

11 PART 2 2 Assessment Criteria of Detection Technology Section 2 describes the key functional specifications against which the available technologies will be assessed. These specifications are completed by non-technical criteria. The candidate technologies are described in Section 3 and the full critical assessment of them is given in Section 4 along with recommendations for the future orientation of the Wake Vortex Separations (WakeSep) project. 2.1 Sensor Performance Criteria This section reviews the list of parameters define in Part 1 of this document with regard to a realistic measurement protocol that sets minimum and maximum measurement ranges Atmospheric parameters Table 2 shows the atmospheric parameters that need to be measured in the different operational phases of interest. Note that these parameters are dimensional, requiring 2-D or 3-D scanning regimens. Table 2 also indicates the measurement requirement in terms of accuracy and data refreshment rate. Table 1 defines the distance ranges within which the candidate technologies must be able to operate. The candidate technologies will be assessed according to the number of these atmospheric parameters they are able to measure, and their ability to meet the performance requirements Measurement protocol The measurement protocol includes the required combination of sensors and their positioning around the area of interest. Physical placement of sensors around the airfield can often be a major source of difficulty. Compromises in the positioning of sensors will have an impact on their real performance. Examples of the positions of sensors for take-off and landing configurations are presented in Figure 3 and Figure Specific Requirements for Scanning Sensors (LIDAR, RADAR) Covered Area Typically this should be a rectangle of about 120m by 60m. To be able to track the vortex pair in case of transverse cross wind, the monitored width should be up to 180m. Scanning refreshment time Typically this should be less than 6 seconds in order to freeze the vortex pattern. Velocity range Typically this should be greater than +/-20 m/s to capture the core velocity. Measurement range Table 1 shows approximate measurement range requirements. The actual performance of the sensors will depend on their location with respect to the runway. EEC/ TRS-C52 - Final report -5-

12 Table 1: System ranges. 2.2 Other General Criteria The system that best meets ATC functional parameters may have operational constraints that would render it useless in an airport area. The following constraints are essential to assess an operational atmospheric monitoring system dedicated to field measurement: Safety These criteria check that the system does not generate hazardous situations due to its technical components: use electromagnetic waves, physical obstacles All weather operations The performances of most systems are impacted by meteorological conditions. It is very difficult to establish a common evaluation range for this criteria and evaluation will be done for each case later on in this document. In the summary assessment grid, we then will simply identify technologies that allow all weather" operations and those which don t Ease of operational set up This is the level of difficulty and cost to move the system from one point to another. This criteria is all the more important in the frame of test and validation campaigns. Level of R&D maturity & Availability for Use What are the risks associated with emerging technologies? When will operational equipment be available to collect field data? Cost (estimated or known) What is the estimated range of prices for a set of systems to cover one runway axis? Other limitations Some systems have very specific limitations that should be gathered in this category. EEC/ TRS-C52 - Final report -6-

13 Approach/climb areas Critical Areas ILS interception area Remote sensing system specifications* Measurement Dimension Mandatory Derived or Modelized Accuracy 25 sec. 1m/s 0,5m/s 1m/s (Average every 2' <1mn Z=50m Z = 15m Z=50m with 1' refresh) Horizontal Windspeed profile 3D X X X Wind direction profile 3D X X N/A 1mn X Windshear profile 3D X 1 m/s X 0,5m/s 1mn X 1 m/s 1 measurement at 10 mn Turbulence (EDR or TKE) 3D X X 10m X Temperature profile (one location only - Same for takeoff and landing) 1D X 1 K Z=100m Data 10mn refreshment rate X Mandatory Derived or Modelized Accuracy Data 1 K 10 mn refreshment rate X Mandatory Derived or Modelized Accuracy 1 K Z=100m Data 25 sec. (Average every 2' with 1' refresh) 10mn refreshment rate Wortex core position 2D X X < 10 m 6 sec. X < 10 m Wortex circulation 2D X X 5 m 2 /s X 5 m 2 /s *Reminder : other parameters Trajectory of the follower aircraft Visibility Ceiling Impact of runway configuration Table 2: Detailed list of functional parameters deduced from users needs. EEC/ TRS-C52 - Final report -7- restricted

14 Figure 3: Measurement protocol for critical arrival areas (ILS Interception, Final Approach and Landing). Figure 4: Measurement protocol for critical departure areas (Take-Off and Initial Climb). EEC/ TRS-C52 - Final report -8- restricted

15 3 OVERVIEW OF CANDIDATE TECHNOLOGIES 3.1 In-situ technologies Weather Tower This consists of a tower with a range of meteorological sensors including anemometers. Parameters retrieved: Turbulence, wind profile (up to 45m), temperature/humidity. Windlines These consist of an array of poles with propeller-vane or sonic anemometers. The windline is deployed in a line perpendicular to the runway axis. The windlines allow wake vortex measurement (position and motion) near the ground. Aircraft Data Down-linked aircraft data can be used for in situ sounding of the entire flight path. Temperature, mean wind speed and direction, as well as EDR can be retrieved in this way. Accuracy is of the order of radiosoundings. 3.2 Remote sensing technologies Detection of wind profiles and wake vortex in Critical areas Pulsed Coherent LIDAR Pulsed LIDAR sensors can monitor both WV and wind profile with high range and temporal resolution. They have been extensively evaluated over recent years at several airports in the USA. They show high levels of performance but are perceived as quite expensive up to now. Low cost systems are in development in the USA and Europe. Lidar range depends on the visibility and is greatest in haze. This relation is shown in Figure 5. The different black lines are separated by a factor 5 in pulse energy. Visibility dependence is less sensitive for short- range operation. If the visibility is less than 100m, the maximum range will not exceed 150 m, whatever the pulse energy. Figure 5: Maximum LIDAR range vs. visibility. EEC/ TRS-C52 - Final report -9- restricted

16 Coherent LIDAR systems need the presence of aerosol particles in the atmosphere. Therefore, they are mostly limited to the probing of the ABL, except during desert-dust outbreak conditions that enhance the aerosol load in the free troposphere. In winter or in cases of strong wind, vertical sounding will be limited to a few tens of meters. That may be a limiting criterion for morning monitoring in the ABL for northern airports like Frankfurt, CDG, Heathrow or Amsterdam. Continuous Wave Coherent LIDAR From the M-FLAME program it has been concluded that CW LIDAR is able to detect and follow WV. ( but performances depend on the mean wind speed and the ability to make very fast focus changes for each line of sight during scanning procedure and wake vortex tracking. Multi-beam LIDAR This is an emerging low cost technology which needs to be further evaluated. LP2C Vortex SODAR This is a new concept of SODAR dedicated to low-layers soundings up to 500m. Wind speed and direction can be retrieved with a height resolution of a few meters (every 1 minute, for small to moderate wind speeds). WV can also be detected up to 150m every 3sec. if they pass in the LOS of the sensor. Phased-Array Acoustic Imaging Mapping of wake vortices can be performed using a large array of microphones, high performance data acquisition hardware and beam-forming software, called an aeroacoustic phased array. Limitations: may be difficult to deploy as it needs many precisely positioned microphones to draw an unambiguous map of the sound source Wind profiles on the glide slope Windlines (see 3.1) Coherent Pulsed & Multi-beam LIDAR (see 3.2.1) Rayleigh Mie Doppler LIDAR These are direct detection LIDAR with long range capability but their performance is not yet satisfactory in term of height and temporal resolution. UHF RADAR Wind profiler UHF RADAR measure the wind profiles by detecting the Doppler shifts in large hydrometeors (rain, snow) and turbulent eddies. Their range is typically 3.5km but can be less in clear air or dry air conditions when almost no reflectors are present. These profilers are adversely affected by strong precipitations, aircraft and birds in the RADAR beams, and side lobe interference. Strong temperature inversions (as found in cold air or at night) and very dry atmospheres can also decrease their performances. Terminal Doppler Wind RADAR (TDWR) The TDWR is a C-Band RADAR that allows the detection of wind shears, micro-bursts, and other hazardous convective activity in the ABL. They use rain droplet velocity to estimate wind velocity. Their performance is quite reduced in clear, dry or cold air. S- or X-Band RADAR These new, low-cost RADAR are currently in development. They use clear air turbulence for wind speed measurement. They may provide a very accurate wind profile in the low layers from 30m up to 500m. Turbulent Eddies Profiler (TEP) RADAR The TEP RADAR focuses on small scale atmospheric phenomenon about 10m scale. A digital beamforming technique can be applied to improve the resolution. EDR measures can be obtained from this instrument. Information may also be found on the wake vortices depending on the range. The current EEC/ TRS-C52 - Final report -10- restricted

17 range is 300 to 1800m. SODAR SODAR (Sound Detection and Ranging) is built on the same principle as RADAR but using acoustic waves instead of RADAR wavelengths. It measures wind velocity profiles based on Doppler shifts in the speed of sound. SODAR provides quite accurate data in height. Long-range SODAR can reach altitudes of up to 1500m (Zack et al. 2003) with a low time resolution (10minutes) and good vertical resolution (30m). Mini-SODAR have also been built and allow a better resolution in the low layers (1minute time resolution and 10m of vertical resolution). SODAR performance can be very limited in noisy environments (>65dB) such as at airports or in adverse atmospheric conditions. Also, winds exceeding 10 m/s may also move the signal out of the cone of the receiver Temperature and Turbulence measurement Radio Acoustic System (RASS) Acoustic sensor used with wind profiler RADAR and SODAR. It allows the determination of temperature profiles. Microwave radiometer (or Oxygen-band radiometer) Passive sensor that scans an arc from horizon to horizon detecting radiation in the 60GHz oxygen band. Temperature is retrieved from radiance Turbulence profiles. Turbulence Turbulence is measured in terms of TKE (Turbulent Kinetic Energy) and TEDR (Turbulent Energy Dissipation Rate). EDR is retrieved from the spatial structure function on the wind velocity or from the width of the Doppler spectrum. Turbulence parameters are of primary importance for wake vortices dissipation rate and descent rate estimation. It is also of secondary interest for the calculation of the lateral transport of WV. A summary of the Candidate Technologies is provided in Table 3 EEC/ TRS-C52 - Final report -11- restricted

18 Commercial Off-the-Shelf Mature R&D Emerging TECHNOLOGY Windline 2µm coherent doppler lidar ABL 2µm coherent doppler lidar CW Lidar UHF radar VHF radar Mini sodar Sodar RASS/SODA R RASS/UHF RADAR Pressure microwave profiler 1.5µm coherent doppler lidar Rayleigh Mie doppler lidar TEP Radar LP 2 C Sodar ABL 1,5µm coherent doppler lidar Band X radar Multibeam lidar Functional specifications Minimum range 1m 100m 60m 20m 75m or 145m 250m 10m 50m 15m 100m 5m 60m 20m 200m 2000m or 5000m 400m (2km in 2007) 15m 60m 20m 1.5m Max range 15m 8km 2.5km 200m 1500m 600m 3500m 600 to 1.5km 1km 2000m 2000m 1500m 500m 2km 3000 Windspeed 0.1m/s m/s m/s 0.05m/s 1m/s >1m/s 0.5 to 1m/s 0.5 to 1m/s 0.5 to 1m/s 0.5 to 1m/s 0.05m/s <1m/s <1m/s accuracy 0.5m/s 0.05m/s 0.5m/s <1 m/s WV core 1m ± 3m ± 3m ± 3m No position 0.3m ± 3m To be tested WV circulation ±5 m2/s ±5 m2/s ±5 m2/s No ±5 m2/s To be tested Spatial resolution Averaging period Safety (radiation, eye ) depending on mast position 60m (3m slant path) 60m (3m slant path) 10m to 100m (depending on range) 60 to 97m m 7.5m 10m 20m m <100m 30 or 60m (3m slant path) m 10m 1m 1sec 1mn 5s 1mn 10-60mn 1mn 5mn to 60mn 5mn to 60mn 1mn to 60mn 3mn to 60mn 1 to 5mn less than 1s 1mn 5s Y Y Y Y Y Y Y Y (check for noise level) Y Y Y Y Y (after 100m range) 3sec for WV, 1minute for windspeed 30 or 60m (3m slant path) less than 1s 500m (80m present) 10-20m 1.5m 2s radial - 1mn for speed and direction 2.5s Y Y Y Y N/A Operational specifications 10 to 15 Size masts of 10m Shelter Shelter 40x40x25 40*30*20 50*100*20 40*30*20 1.2m diam. Weight 2.73T >100kg 10kg >100kg >100kg 8kg >100kg 10kg 15kg >100kg >100kg 10kg <20kg? Power consumption Very Low medium Low Very Low High High Low Low Low High Low Very Low Low Very Low Low Low Weather limitations Other limitations Weak aerosol load, very dense fog, ceiling Weak aerosol load, very dense fog, ceiling Weak aerosol load, very dense fog, ceiling Clear or cold air, strong temp inversion, heavy rain Clear or cold air, strong temp inversion, heavy rain Clear or cold air, strong temp inversion, strong winds Noise from the sensor, echoes around antenna (>65DBa) Clear or cold air, strong temp inversion, strong winds Noise from the sensor, echoes around antenna (>75dBa) Clear or cold air, strong temp inversion, strong winds Clear or cold air, strong temp inversion, heavy rain Weak Weak aerosol load, aerosol load, very dense very dense fog, ceiling fog, ceiling Economical specifications Prototype Mid March 05 sept-05 Yes Yes 2007 availability (Proto) N/A Commercial product Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Unplanned Planned 2008 Unplanned No availability Level of R&D uncertainty None Very low N/A Low Very low Medium? Low Cost <30k 1.05M 210k 100k ~210k N/A 35k 105k 35k (RASS 28k (RASS 84k 150k 150k N/A only) only) N/A N/A Non exhaustive list of private and public developers CTI CTI Qinetiq Degreane, Vaisala Degreane, Vaisala Remteck, Meteck Remteck, Meteck Remteck, Meteck Degreane, Vaisala Radiometrics Corp. ONERA, DLR, Qinetiq CNRS /SA Heavy rain Clear or cold air, strong temp inversion, strong winds Univ; Massachuset ts NCAR Weak aerosol load, very dense fog, ceiling Fidelio (Onera) heavy rain CNRS / CETP Very dense fog, ceiling NASA Table 3: Overview of candidate technologies. EEC/ TRS-C52 Final report -12- restricted

19 4 CRITICAL ASSESSMENT of the CANDIDATE TECHNOLOGIES 4.1 ASSESSMENT METHOD Candidate technologies have been first evaluated in term of their ability to fit into the defined functional parameters from chapter. General results are shown in Table 7 and Table 8 (see the Appendixes). There is no one best solution. This study gives preliminary recommendations in order to start field validation work. Other emerging technologies that meet specifications will have an opportunity to join this test phase later on. The selected technologies have then been compared in terms of maturity, all weather use and ease of deployment. Table 7 serves as a reference document if a detailed project analysis is needed for the development of a technology case. The aim of this analysis is to define the best synergy that must be used in order to furnish the necessary atmospheric information at each area under controller responsibility. Obviously, different kinds of packages will have to be defined depending on the airport localisation and configuration. 4.2 CRITICAL ANALYSIS OF THE SENSORS Conformity to Performance Criteria See Appendixes, Table 8: Technological assessment against detection capabilities and areas to reach Technology for WV detection Up to now, LIDAR appeared to be the only reliable technology for wake vortex detection. LIDAR technology has been validated during several short- and long-term field campaigns (e.g. Tarbes, Oberpfaffenhofen, St Louis). The analysis of COTS and mature research sensors shows that new capabilities will soon be available, especially for monitoring low layers. Resolution of RADAR and SODAR will be enhanced. Also new processing techniques have been developed for both retrieval of wind data and noise filtering. New high resolution LIDAR, RADAR and SODAR may be available in 2 to 5 years enabling monitoring of wind and turbulence in the critical areas. Also, LIDAR developers have made efforts to enhance the range of their systems. New laser components have also emerged since the 90 s. As a consequence of these efforts, the price of LIDAR systems has decreased. Compared to other technologies, long range LIDAR seem to be the only tools able control landing areas of parallel runways Impact of measurement protocol Sensor position for the monitoring of critical areas Two positions are possible when scanning planes at acute angles from an axis perpendicular to the aircraft s flight axis: under the flight path or sideways. Under the flight path which allows the two vortices to be separated angularly, but needs a large scan angle when the vortex is low. Sideways, with a vertical scan perpendicular to the corridor axis. This is non-symmetrical but is well suited to track vortices down to the ground. Scan angle is reduced and probed volume is larger, allowing wind to move the WV. To maximize WV capture, the best position is at the beginning of the landing zone, 2500 m upstream from the touch down area. Because long range is more demanding for the LIDAR, the instrument should be placed as close as possible, taking into account a maximum scan angle of 60. In this case, the remote sensor must reach 280m of range in EEC/ TRS-C52 Final report -13- restricted

20 order to cover the entire area. Sensor position for Approach / climb areas The best position is definitely under the ILS interception area, located 25km upstream from the runway. The LIDAR should either scan towards two opposite directions with a zenith angle of +/-30, or use a co nical scan pattern, having a half angle of 30. A more refined solution would be to propose a tracking of the aircraft using a video camera or radar as a guide for the LIDAR to probe at the correct section. It would fasten the operation as the system has to scan in the vertical plan only once per departure. These solutions need to be further studied and tested. Systems for both Take-Off and Landing Parameters of landing and take-off areas are different (larger volume to probe, degree of freedom for pilots during take-off) and there is potentially an exchange of landing and take-off areas up to six times a day (depending on the wind direction, strength and solar dazzle). For airports that have chosen to keep dedicated runways for take off or landing, as in CDG, the choice of remote sensors dedicated to critical areas monitoring will be larger. Candidates Coherent pulsed LIDAR and CW LIDAR provide the only near-term operational system for WV detection both in landing and take-off areas. Emerging technologies, such as X-band RADAR or multi-beam LIDAR need to be further developed, tested and validated. Pulsed coherent LIDAR has the advantage of a longer range and a better spatial resolution. However, these systems are relatively expensive compared to recent COTS CW LIDARS or upcoming 1.5µm coherent pulsed LIDAR Impact of weather conditions Weather conditions classification In Table 4, remote sensors have been classified against different weather categories. For example, in clear sky conditions RADAR will have limitations due to the absence of turbulent eddies or hydrometeors. Sub categories have also been added in order to discriminate between cases where the Atmospheric Boundary Layer (ABL) is above the maximum height of the selected area or under. This parameter is necessary because of the dramatic decrease of SODAR performance in the presence of low inversion layer height and of LIDAR performance in cases of absence of sufficient aerosol load (as can be found above ABL in winter when no forest fires, dust outbreak or other natural or anthropogenic events occur). Critical areas From Table 4, it is clear that Pulsed or CW Coherent LIDAR are very good candidates for monitoring critical areas as they adhere to most of the requirements. For very bad weather conditions, windlines and Met towers with sonic anemometers will be necessary to get WV position near the ground and high resolution wind profile in the low layers (0 to 40meters). Also a RASS/SODAR needs to be added to this package for temperature profile retrieval. Approach / Climb areas Due to longer ranges, only the 2µm Pulsed Coherent LIDAR can fulfil the requirements from the LIDAR systems. For bad weather or visibility conditions, UHF RADAR or scanning TDWR will replace LIDARS. TDWR has the advantage of being able to keep working under conditions of strong precipitation. However, this system is more expensive than most RADAR. Temperature profile will be monitored preferentially by RASS/SODAR to fulfil most of the conditions. EEC/ TRS-C52 Final report -14- restricted

21 WV monitoring Wind profiles Turbulence profile Temperature profiles a Clear sky & stratified Limitating Atmospheric conditions* ABL > 120m COTS Pulsed Coherent LIDAR CW LIDAR LP2C SODAR 1.5µm short range Pulsed Coherent LIDAR COTS Pulsed COTS Pulsed Coherent LIDAR Coherent LIDAR CW LIDAR CW LIDAR LP2C SODAR LP2C SODAR 1.5µm short range Pulsed 1.5µm short range Coherent LIDAR Pulsed Coherent LIDAR Microwave radiometer, RASS/SODAR ABL < 120m Windlines Windline, Met tower Met tower Microwave radiometer Low clouds (stratus) Above 120m COTS Pulsed Coherent LIDAR CW LIDAR LP2C SODAR 1.5µm short range Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR CW LIDAR CW LIDAR LP2C SODAR LP2C SODAR 1.5µm short range 1.5µm short range Pulsed Pulsed Coherent LIDAR Coherent LIDAR MiniSODAR + Met Tower Microwave radiometer, RASS/SODAR Below 120m Windline Windline Met tower + three sonic anemometer Microwave radiometer, RASS/SODAR Very low visibility (cat.3) Windline LP2C SODAR Mini SODAR Heavy precipitation Windline TDWR Met tower + three sonic anemometer Met tower + three sonic anemometer Microwave radiometer, RASS/SODAR Met tower Clear sky Low clouds (stratus) Very low visibility (cat.3) Heavy precipitation ABL > 120m COTS Pulsed Coherent LIDAR Microwave radiometer, RASS/SODAR ABL < 120m None Microwave radiometer Above 120 m 2µ Pulsed Coherent LIDAR, UHF RADAR, SODAR, TEP RADAR Microwave radiometer, RASS/SODAR Below 120m Microwave radiometer, TDWR RASS/RADAR UHF RADAR, SODAR, TEP RADAR TDWR Microwave radiometer, RASS/SODAR, RASS/RADAR Clear sky Low clouds (stratus) ABL > 1500m ABL < 1500m Above 1500m COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR COTS Pulsed Coherent LIDAR TEP RADAR COTS Pulsed Coherent LIDAR None COTS Pulsed Coherent LIDAR TEP RADAR Microwave radiometer, RASS/ UHF RADAR Microwave radiometer, RASS/ UHF RADAR Microwave radiometer, RASS/ UHF RADAR Microwave radiometer, RASS/ UHF Below 1500m None TEP RADAR TEP RADAR RADAR Very low visibility (cat.3) None TEP RADAR TEP RADAR Microwave radiometer Heavy precipitation None TDWR None epresent COST sensors epresent mature R&D technologies ed to be satisfactory for operationnal configuration unless losing more than 50% situations Table 4: Remote sensors classification vs. functional parameters and limiting atmospheric conditions. COTS and mature R&D remote sensors have been assessed. ILS interception area 2µm pulsed coherent LIDAR may detect and monitor WV on the ILS. In cases of very low visibility and heavy rain the 2µm coherent pulsed LIDAR will not able to cover all of the ILS area. No sensor will be able to monitor wake vortices in this area in these conditions. Only a TDWR or the R&D TEP RADAR will be able to get wind and turbulence profiles in such conditions. Except for windlines, all technologies are subject to weather limitations. Luckily some technologies may be complementary and propose an almost complete solution. For example, LIDAR are range-limited in cases of very dense fog or precipitations (rain or snow). For wind profile retrieval, RADAR or SODAR may be a good complement to LIDAR due to their ability to probe in poor visibility or bad weather conditions. However both RADAR and SODAR are also limited in heavy rain conditions, although efforts are currently being made to improve the technology, including post processing data treatment to remove this limitation. For example, the TDWR RADAR is designed to measure the wind profile under rainy conditions. Its scanning capabilities allow the retrieval of accurate wind profiles in the lower areas, making it a good complement to the pulsed coherent LIDAR for wind profiles and wind shear monitoring. EEC/ TRS-C52 Final report -15- restricted

22 Windlines remain as an almost mandatory tool for all operational configurations as they allow significant information on wake vortices to be obtained under any meteorological conditions. 5 RECOMMENDED TECHNICAL SOLUTIONS 5.1 Introduction The purpose of this chapter is to recommend a first operational solution that could be used for a short-term (2006) measurement campaign in a leading European airport for WV detection. As far as a long term (2010) operational wake vortex monitoring system is concerned, there is no detailed and rational answer at this time; several points provide interesting material to be further analysed: Emerging technologies that have been identified and pre-analysed in this document will have to be taken into consideration in the design of next generation WV monitoring systems. The short-term operational WV detection solution recommended here will also provide a solid basis for a long-term operational solution. Another requested intermediary target was to establish a basic list of preparatory works to perform before an operational solution is deployed. This preparatory work has two objectives: To validate the recommended operational solution described below To optimize this solution in terms of performance and economics; in particular, by including results of current R&D, particularly performance and cost, that we have not wanted to take for granted as we were writing this document. 5.2 Refined functional specifications In addition to the initial functional specifications listed in Part 1 of this document, the critical assessment we have performed showed that the ABL height (or inversion layer height) is a key indicator that influences both the atmospheric parameters and the performances of sensors such as LIDAR or SODAR. Indeed, strong temperature inversion has a consequent effect on mean wind, wind shear and turbulence. Winds can change very rapidly at the top of the nocturnal inversion layer. Thus it is essential to know with accuracy the time and vertical evolution of the height of the inversion during the transition phase in the morning and the evening. Limited cost Rayleigh-Mie LIDAR may be used for ABL height detection and temporal evolution monitoring with high accuracy (less than 20m). 5.3 Orientation for technology case Based on our critical analysis, two technical solutions have been identified: Short term Optimal Operational solution An "ideal" package, that meets most of the functional and operational requirements, through a combination of the following technologies: 2µm PC LIDAR (two systems) Windlines (two at least) Met Tower TDWR for wind profiles measurements under the rain. RASS SODAR for wind and temperature monitoring. This package is presented in table 5. Note that foggy conditions for upper areas (ILS and Approach / Climb) are not covered by any instrument in this package. EEC/ TRS-C52 Final report -16- restricted

23 0 0 Table 5 : Ideal short term operational package Short-Term Low Cost Operational Solution An alternative cheaper package would feature the same instruments except for the TDWR and RASS SODAR that would be replaced by an UHF profiler equipped with RASS for temperature profiling. This solution would reduce costs but would not be operational under heavy rain. Latest improvements of COTS RADAR in terms of range and time resolution could make these instruments worth considering for this package. Overall, we remain pessimistic regarding the an all-weather operating system and would rather recommend targeting a first short-term operational solution that reverts to ICAO standard spacing during heavy precipitation (rain or snow) in order to ensure safety Mid-term solution Anticipating the rise of new technologies that have been described in this document, we propose a substitute package to the short term proposal (see Table 6). This new proposal may be available in the next 5 years. The new generation of PC LIDAR may replace the current solutions with reduced cost and size. S-band RADAR seem promising for wind and turbulence monitoring even under foggy conditions. They may also be used for WV detection but this needs to be correctly evaluated. TEP RADAR also shows good potential for approach/climb area monitoring (for wind and turbulence) under different weather conditions (including fog and rain). 0 0 Long range 1.5µm PC Lidar TEP RADAR LIDAR PC1.5µm LP2C SODAR (landing) X/S band radar Microwave radiometer Table 6 : Substitute package for a middle term solution EEC/ TRS-C52 Final report -17- restricted

24 5.3.4 Preparatory work The aim of these technical recommendations is to show that a reliable and available solution does exist and to start working on it. Preparatory work is needed to allow the testing of promising R&D technologies that will reduce costs and associated risk. We recommend a two-step approach to limiting risk and cost. First establish a reliable solution that fits all airport configurations then offer adapted solutions to different airports Validate a Common-core Solution The following is a preliminary list of work that needs to be refined, planned and cost-estimated in cooperation with the various stakeholders: airport authorities, ATC experts, sensor researchers & manufacturers. Check the performance of the selected technologies on a long-term basis, which will allow verification of the overall reliability of the sensors and their maintenance needs. In the short term, COTS and mature R&D remote sensors need to be evaluated against the mandatory parameters and for all-weather conditions. The result of such a campaign will not only validate the one solution, but also provide detailed information of the limitations of each system versus various operational constraints. This information will help choose downgraded technologies for airports having a lower level of meteorological or ATC constraints and thus, adapt investments. Evaluate the opportunity for upgrading or replacement of some sensors with current R&D sub-systems. In particular: New enhanced resolution radars New 1.5µm PC LIDAR New VORTEX SODAR from US research Horizontal wind field short term forecasting of dynamic radar clutter evolution (Skewing) and Doppler processing algorithms (DOPVOR) adapted to radar (approached in ATC WAKE) Enhance the knowledge of wake vortices behavioural variation across the seasons and different weather categories. This will help define a time and cost limited validation procedure necessary to prepare the translation of the common core solution into a local solution for each airport. Elaborate a measurement protocol that optimises the performance / cost ratio. Positions of the sensors will be optimised during this long-term campaign allowing the acquisition of knowledge regarding the limitations and advantages of each configuration. Former knowledge acquired during M-Flame and US campaigns will be of great help and must be carefully studied and integrated when defining the evaluation protocol definition. Write technical specifications for the algorithm associated with the chosen instrument s assembly and develop integrated algorithms for WV monitoring and for interfacing with a wake vortex advisory general module for ATC Controllers. Enrich the database that will feed the future system in terms of meteorological conditions Adapted Common-core Scenario for Major Airports For each airport, the solution will depend on several factors, among them: Weather Infrastructure (e.g. closely-spaced runways < 2500feet). ATC procedures (staggered approaches) Expected benefits of the use of the WV detection system. EEC/ TRS-C52 Final report -18- restricted