INTERNATIONAL BIRD STRIKE COMMITTEE IBSC27/WP X-3 Athens, May 2005 BIRD AVOIDANCE MODELS VS. REALTIME BIRDSTRIKE WARNING SYSTEMS A COMPARISON

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1 INTERNATIONAL BIRD STRIKE COMMITTEE IBSC27/WP X-3 Athens, May 2005 BIRD AVOIDANCE MODELS VS. REALTIME BIRDSTRIKE WARNING SYSTEMS A COMPARISON Wilhelm Ruhe, Dipl.Met., M.Sc. Bundeswehr Ge Infrmatin Office, Bilgy Sectin, Mnt Ryal, D Traben-Trarbach, Germany Tel: , Fax: , WilhelmRuhe@bundeswehr.rg Abstract Bird Avidance Mdels prvide either shrt range bird strike risk frecasts r histrically based average bird strike risk levels. Bird strike warning systems are based n real time mnitring and bird strike risk assessment f imminent bird hazard. In military aviatin bth cncepts have prven t be effective tls t decrease the number f bird aircraft cllisins. Based n persnal knwledge abut current mdels and systems as well as the experience with the Bundeswehr Geinfrmatin Office Real Time Observatin and Warning System and wrking with the US and Alaska BAM the basic design cncepts, advantages and limitatins are discussed. An attempt is being made t define and classify different types f existing mdels/systems and a prpsal is made n a standardisatin f naming cnventins, which appears t be necessary, in rder t use the same wrding fr similar prducts and nt cnfuse the aviatin cmmunity. Keywrds: Bird Migratin, Bird Strike Warning, BIRDTAM, Bird Strike Risk Frecast, Avidance, Radar 1. Intrductin Birdstrike preventin apart the airfield is mst effectively cnducted by warning prcedures. As there is n direct interference pssible t influence bird activity alft, the nly chance t minimize the risk f bird strikes is t avid flying thrugh high bird cncentratins in the air. The presence f hazardus bird cncentratins are well knwn during migratin perids in the large tempral and spatial scale. But they als ccur ccatinally thrughut the year n a lcal r reginal scale, mainly gverned by the diurnal cycle. Mnitring, mdelling, warning, predicting, frecasting are the majr aspects f handling the prblem and result in a certain advise, that is passed t the aviatin cmmunity. In military aviatin there is ften a gd chance t change flight schedules accrding t bird strike warnings. This hwever is rarely pssible in civil aviatin. But, the awareness f an increased risk prepares fr decisins that need t be made in case f a serius impact. The fllwing gives a brief verlk and discussin n sme currently existing mdels, systems, methdlgies and cncepts. These mdels are all develped fr the large spatial scale, bigger than the airprt scale. It immediately becmes bvius that wrding and naming shuld be carefully chsen in rder nt t cnfuse the aviatin cmmunity, e. g. what is cnsidered t be a mdel and what characterizes a system. This surely needs sme discussin, but, a first attempt and prpsal is made fr a standardizatin, especially under the perspective f future internatinal cperatin and glbalizatin. 1

2 IBSC27/WP X-3 2. Bird Avidance Mdels a. United States Bird Avidance Mdel The USBAM is based n apprx. 30 years f histric bird bservatin data fr winter and summer distributins. These pint data are transfrmed int average bird mass values and are interplated spatially in a GIS envirnment fr each f the birdstrike relevant species with a reslutin f 1 km ². The latest extensin fr Alaska als takes land cver characteristics int accunt fr mre realistic bird distributins in areas where data are sparse. Between the winter and the summer distributin a tempral interplatin is cnducted, based n diurnal and annual activity pattern, breeding success and mrtality rate. The verall average mass f birds per km² is transfrmed int 9 bird strike risk levels accrding t a lgarithmic scale. Mdel utput is displayed in an internet map applicatin that cmbines the birdstrike risk level infrmatin with additinal imprtant map infrmatin fr aviatrs. Mdelling in this case stands fr an widely autmized prcess t transfrm the histric bird cunt infrmatin int average time and space dependent birdstrike risk levels. Updates accrding t new data are prvided apprx. every 2-5 years. b. German Birdstrike Risk Frecast Mdel A different mdelling apprach is used in the peratinal German Birdstrike Risk Frecast Mdel. Statistical crrelatin analysis n the weather dependency f bird migratin results in a decisin tree algrithm fr each seasn. The parameter s used are wind speed, wind directin, temperature, temperature change, precipitatin intensity and sil cnditins. Based n rnithlgical expert knwledge and up-t-date weather frecasts a 24 hur frecast and a 3-day utlk fr 13 gegraphical regins in Germany are derived and transmitted t the German Frces where they becme part f the daily flight weather briefing. The currently still manually cnducted mdelling prcess is the transfrmatin f weather frecasts and rnithlgical knwledge int a bird strike risk frecast. Updates are prvided daily, during main migratin perids twice daily. c. Swiss/Dutch Dynamic Bird Migratin Mdel The mst recent and nt yet peratinal apprach t mdel bird migratin as the basis fr bird strike risk assessments and frecasts is a fluid dynamic algrithm develped by Swiss and Dutch researchers. The grid based mdel currently uses a species dependent energy balance mdel and the wind cmpnent frm peratinal numerical weather frecasts t simulate the flight path f birds starting in a certain area. The mdel area extends all ver Eurpe and Nrthern Africa. The cnceptual algrithm is flexible t accunt fr new and additinal sub-mdels. Mdelling is based n physical and bilgical rules and is a fully autmized numerical prcess. Updates can be run any time and are able t accunt fr any changes in input r parameter values. 3. Real Time Birdstrike Warning Systems a. United States Avian Hazard Advisry System The United States AHAS System prvides bird strike advisry infrmatin t clients via web applicatin n request. It uses the USBAM bird strike risk levels as the base line that prvides the average risk level fr any time and lcatin in the US. Fr a current shrt range frecast up t 24 hurs numerical weather frecasts and specific mdules that accunt fr thermal activity are prcessed by neural netwrk technlgy t get an up-t-date birdstrike risk infrmatin and nwcast. A nwcast up t 1 hur is additinally prcessed and updated by NEXRAD-Weatherradar data. A trend is assessed and displayed fr anther hur if applicable. Infrmatin is presented in tabular frmat, presenting the details fr military flight rutes, training areas, airfields and military peratins areas. Advisries cntain a risk level f either lw, mderate r severe. N altitudinal infrmatin is 2

3 Ruhe given, hwever it is implied, that the risk level is valid fr the lwest 3000 ft AGL. Current infrmatin is updated hurly by NEXRAD-Data. Meterlgical frecasts are incrprated every 12 hurs. The system cnsists f a central server architecture, including a web and internet map server. Data are taken statinary frm the GIS based USBAM risk surfaces and dynamically via brad band cmmunicatin links t the US Natinal Weather Service fr dwnlading NEXRAD-Data and numerical weather frecasts. The infrmatin is displayed by user request frm n the internet. a. Dutch ROBIN System A majr cmpnent f the Dutch Radar Observatin f Bird Intensities System is the scientifically sphisticated bird radar data prcessing unit which is especially designed and ptimized fr bird detectin. Besides sme tw-dimensinal air traffic cntrl radars the tw main radar systems are lng range air defense radars. The raw data extracted frm these radars are taken frm the lwest tw beams, which allws fr a rugh estimate n the altitudinal distributin f eches. Tracking radar systems and small mbile radars are partly and temprary used t directly measure the altitude f flcks. The cmputer supprted analysis is cnducted by experts at a central lcatin where all the data are available. Birdstrike warnings are submitted t natinal military users and internatinally via flight safety netwrk. b. German BIRDTAM System Based n existing military infrastructure and a central agency within a gephysical service the German BIRDTAM System is an efficiency ptimized peratinal system. It uses reliable visual bird bservatin taken frm trained weather bservers and pilts, radar reprts frm air traffic cntrl units and bird radar data frm air defense radar systems. The latter is the backbne f the system. Althugh the currently used data are peratinally filtered, s that sme areas are masked and sme eches are suppressed accrding t the needs f the cntrller persnal, high intensities f bird migratin are still visible. The system cvers the area and detects in three dimensins. Data gathering and prcessing is widely cmputerized and autmized, but interpretatin and analysis is needed. An expert system is used t supprt the experts. Warnings are created and submitted in real time by the cmputerized system. The cmmunicatin systems used are the meterlgical and the military and civil aviatin flight safety netwrks as well as direct cmmunicatin links between radars and the analysis center. Warning situatins are als displayed n the internet. c. Cmparing Mdel and System Characteristics Mdels and systems described abve have in cmmn that there verall gal is t assist in reducing bird strikes. The methdlgies hwever are partly very different, resulting frm the availability f data and cmmunicatin netwrks and their histrical develpment. Cnfusing, even within the IBSC cmmunity, is the nt existing clear definitin f the wrding used. Other than, e.g. in meterlgy, the wrd mdel assciates with different meanings. In rder t better describe the type f mdel it shuld be named a cnceptual, a statistical r a simulatin mdel, as it is the case in the atmspheric sciences. - The statistical mdel is based n histric data recrds and prvides a statistic r stchastic infrmatin. - The cnceptual mdel is based n current data and a mathematically-physically representatin f a relatinship t frecast a situatin int the near future. - The simulatin mdel describes a relatinship between certain input values and utput values that prvides n infrmatin n a future situatin. 3

4 IBSC27/WP X-3 The USBAM is a typical statistical mdel. The infrmatin that it prvides is a predictin f an average situatin. It des nt tell the user abut the prbability f its ccurrence. Hwever, the infrmatin is valuable fr planning in lng tempral scales and has a psitive effect in shrt term missin scheduling and planning. In the lng run there is a psitive effect n bird strike reductin, in shrt term it can well be negative. The German Birdstrike Risk Frecast Mdel can be classified as a cnceptual mdel. It uses relatinships between weather parameters and bird activity. Frecasting bird strike risk is based n numerical and heuristic weather frecasts as the frcing elements. Althugh the term Risk might be misleading, it prvides shrt range frecasts f birdstrike risk levels clse t reality. Accuracy depends n the meterlgical frecast skill and the accuracy f the crrelatin. The methdlgy allws fr further imprvement. The Swiss/Dutch Dynamic Bird Migratin Mdel in its current state perfrms as a simulatin mdel, althugh its basis is a cnceptual apprach. Linking bird behaviur and weather frecasts accunts fr high accuracy. Difficulties are the lack f knwledge n parameter values fr individual bird species and the apprach t mdel each species, even individuals, separately. The mst sphisticated theretical backgrund needs t be parameter ptimized, calibrated and build int an verall frecasting mdel. All the Systems have in cmmn that they are prviding bird intensity infrmatin mainly fcussing n the very near future, a Nwcast in meterlgical terms. They all rely n real time bservatins and use cmmunicatin netwrks. Output gal is t generally prvide warnings fr abve average bird cncentratins. Whereas the data analysis, whether autmized, partially autmized r manually, is relatively cmplex, the warning generatin algrithm is rather simple. The assumptin is, that in a shrt-term nwcast there is n big change in the influencing factrs like weather cnditins. Based n what has been described and discussed abve, imprtant differences between Mdels and Systems are that Mdels are mre independent n real time data than Warning Systems. Mdels fcus n frecasts r predictins and use cmplex algrithms t extend the frecast perid int the future r display statistical infrmatin. Systems generally cnsist f cmplex hard and sftware infrastructure. Classical cmpnents are bservatin, analysis, cmmunicatin, display. Systems are pen fr new cmpnents. Usually they are in an peratinal envirnment and have t be adapted t the user s demands. d. Naming cnventin prpsal In rder t vercme cnfusin in naming different methdlgies and definitins, the fllwing definitins are prpsed and shuld be subject f further discussin within the IBSC: Birdstrike Risk Prbability f birdstrikes at a certain density f birds. It als depends f the aircraft type, aircraft speed and ther factrs Bird Hazard Increased birdstrike risk that is well abve average at a specific time and lcatin. Bird Avidance N aviatin in areas with knwn hazardus bird strike risk. Bird Awareness Aviatin under knwn hazardus cnditins and being specifically prepared t take actins. Technique, Algrithm Theretical physically, mathematically based structure t describe a specific prcess. 4

5 Ruhe Mdel Framewrk f techniques and algrithms t theretically describe a real wrld system in rder t either predict r frecast a situatin. System Interacting Cmpnents, such as mdels, sensrs, cmmunicatin netwrks t utilize mdel utputs. Simulatin Mdelling f a real wrld system t red and understand a knwn situatin. Advisry Infrmatin based n best available knwledge fr decisin making. Warning Infrmatin abut a critical situatin. Predictin Infrmatin abut an expected situatin that is based n statistical significance and prbabillity. Frecast Infrmatin abut an expected situatin in the near future based n bservatin and mdelling. Nwcast Infrmatin abut a current bserved situatin that is extraplated int the very clse future Real Time Very clse t present. Histrically Based n lng recrds f data. e. Cnclusins Under the perspective f glbalizatin and that new mdels and systems are abut t be develped in Nrth America and elsewhere, these and existing natinal methdlgies shuld be standardized s that at least the utput and user interface shuld fllw similar cnventins. Cmprehensive Advisry Systems culd cmbine mdels and systems under ne umbrella s that infrmatin can be prvided in different spatial and tempral scales and serve different needs. A distinctin has t be made n the spatial scale whether it is small (airprt) scale r large (missin) scale. The tempral scale has t be divided int lng term predictin, shrt r medium term frecasting and real time nwcasting. The scale clearly defines the methdlgy being used. Wrding shuld be carefully chsen in rder t avid misunderstanding in internatinal cmmunicatin. 5

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