Study on Conflict Detection Method with Downlink Aircraft Parameters

Transcription

1 Study on Conflct Detecton Method wth Downlnk Arcraft Parameters Atsush SENOGUCHI, and Yutaka FUKUDA Ar Traffc Management Dvson Electronc Navgaton Research Insttute Tokyo, Jaan Abstract In order to kee safety of ar traffc, ENRI (Electronc Navgaton Research Insttute) tres to mrove CA (Conflct Alert) functon by usng arborne nformaton va Mode S datalnk. CA suorts ar traffc controller to kee safe searatons between arcraft by redctng arcraft ostons and detectng otental conflcts. Our urose of ths study s to develo the new DAPs-CDM (Conflct Detecton Method usng Downlnk Arcraft Parameters) and evaluate the macts of ts ntroducton by comuter smulaton. Frstly, n order to understand the characterstcs of the conventonal CDM, we calculated horzontal and vertcal redcton errors of arcraft oston. The conventonal CDM uses lnear redcton wth only radar nformaton on the ground. We also analyzed CA occurrences by the conventonal CDM. We found that both horzontal and vertcal redcton errors were reduced by usng arborne nformaton n addton to radar nformaton. We also found that t was better to smooth vertcal seed for redcton and to utlze selected alttude n DAPs-CDM. Fnally, the characterstcs of DAPs-CDM were studed and the advantages were demonstrated. The new functon of DAPs- CDM s to redct arcraft ostons by usng arcraft velocty on the arborne sde and to determne arcraft flght hases by usng roll angle and selected alttude. For the urose of comarng DAPs-CDM wth the conventonal CDM, ENRI develoed CDES (Conflct Detecton Evaluaton System). It can smulate both DAPs-CDM and the conventonal CDM under ar traffc stuatons and system arameters as almost same as oeratonal ones. As a result of comuter smulaton wth CDES, the determnaton of vertcal flght hases by selected alttude was most effectve to reduce the number of unnecessary CA. Keywords-comonent; Conflct Alert; Conflct Detecton Method; Downlnk Arcraft Parameters I. INTRODUCTION From the ersectve of safety, t s necessary to ensure sacng between arcraft. In Jaan, the horzontal searaton mnmum s 5 NM (1 NM = 1,852 m) under radar control. The vertcal searaton mnmum s 1,000 ft (1 ft = m) where alttude s below 41,000 ft under IFR (Instrument Flght Rules) and RVSM (Reduced Vertcal Searaton mnmum), or 2,000 ft where alttude s above 41,000 ft. [1] The stuaton that a roxmty dstance between arcraft and another cannot be satsfed wth both the horzontal and vertcal mnma s called as a conflct. In order to ensure roer sacng between arcraft, ar traffc controller ssues some nstructons to arcraft as needed, based on the stuatons of ar traffc. RDP (Radar Data Processng System), whch ar traffc controller uses for en-route arsace n Jaan, has the functon of redctng arcraft ostons and detectng otental conflcts; called CA (Conflct Alert). Ths functon redcts arcraft ostons n 3 mnutes future, usng current arcraft ostons and estmated arcraft veloctes by trackng rocess. When a otental conflct s detected, a warnng message for ar traffc controller wll be dslayed on RDP screen. [2] In the functon, arcraft s assumed to fly wth constant seed. Therefore, when redctng arcraft ostons, redcton error s occurred by estmaton dfferences and fluctuatons of arcraft velocty. It s also dffcult to redct the changes of arcraft flght hases such as from straght to turn and from clmb to cruse due to lnear redcton. Currently, SSR (Secondary Survellance Radar) Mode S, whch s a new radar system for ar traffc control, s beng ntroduced. Mode S s able not only to get arcraft ostons more accurately, but also to have the functon of dgtal communcaton to downlnk some arcraft arameters such as ground seed, vertcal seed, magnetc headng and selected alttude. These arborne arameters avalable on the ground sde are exected to contrbute the mrovements of ar traffc management. In terms of conflct detecton, the usage of DAPs (Downlnk Arcraft Parameters) wll reduce the number of unnecessary CA and workload of ar traffc controller. [3] The urose of ths study s to develo the new DAPs- CDM (Conflct Detecton Method usng Downlnk Arcraft Parameters) and evaluate the effectveness of ts ntroducton by comuter smulaton. [4] Frst, overvews on CA and CDM (Conflct Detecton Method) are ntroduced n Secton 2 and 3 to renforce research background. Then, n order to understand CDM well, the results of analyzng redcton error on DAPs-CDM are exlaned n Secton 4. More over, for the same urose, the analyses on the stuaton that CA occurred are exlaned n Secton 5. Fnally, n Secton 6, the characterstcs of DAPs-

2 CDM are studed and the results of smulaton whch verfy the effectveness of ts ntroducton are demonstrated. II. INTERNATIONAL TREND OF CA AND MODE S Internatonal trends about STCA (Short Term Conflct Alert) are ntroduced. The trend of SSR Mode S n the Euroe s also ntroduced. A. Internatonal Trend of STCA Reference [5], ublshed by ICAO (Internatonal Cvl Avaton Organzaton) n 2001, descrbes the rocedures of STCA; e.g., A statstcal analyss should be made of justfed alerts n order to dentfy ossble shortcomngs n arsace desgn and ATC rocedures as well as to montor overall safety levels. EUROCONTROL develoed the oeratonal requrements of STCA n [6] For the urose of mrovng safety of ar traffc, SSAP (The Euroean Strategc Safety Acton Plan) was conducted n After SSAP, ESP (Euroean Safety Programme for ATM) also was conducted n ESP made the mrovement lans of safety n 5 man felds and one of them was to consoldate system safety nets. STCA was consdered as a functon for safety on the ground systems. Because the functons and rocedures of STCA were not standardzed n Euroean countres, the secfcaton and gudance of STCA were made. [7][8] Polcy, tranng, regulaton and requrement are descrbed n the secfcaton from the vewont of management. The gudance refers to STCA more techncally. Now, the efforts of safety mrovement by STCA usng enrched survellance nformaton are beng conducted n SESAR Master Plan. [9] B. Mode S Trend The nternatonal standard of BDS (Comm-B Data Selector) code about SSR Mode S was mlemented n [10], ublshed by ICAO n In Euroe, SSR Mode S ELS (Elementary Survellance) was mlemented. Also, Mode S EHS (Enhanced Survellance) was mlemented n the France, Germany, and England. [11] Necessary Caablty for ELS BDS 1,0; Data Lnk Caablty BDS 1,7; Common Usage GICB Caablty BDS 2,0; Arcraft Identfcaton Necessary Caablty for EHS BDS 4,0; Selected Vertcal Intenton BDS 5,0; Track and Turn BDS 6,0; Headng and Seed In Jaan, arcraft whch equs the transonder aled to Mode S data-lnk caablty are ncreasng. [12] III. CONFLICT ALERT IN JAPAN Ths secton exlans a functon overvew of CA and CDM n Jaan. In 1979, CA was mlemented as one of RDP functons. In 2002, CDM wth flght lan nformaton was added to CA functon. [13][14] Fg. 1 shows an examle of CA dslay. Trangle symbols stand for arcraft ostons and each symbol has one nformaton tag. Informaton tag dslays call sgn at the frst row, alttude nformaton at the second row and ground seed at the thrd row. If CA functon detects some otental conflcts u to 3 mnutes, t dslays CNF blnks nto nformaton tags of related arcraft and, at the same tme, renews a CA status lst. In Fg. 1, t lst s shown at the uer left corner. CNF ALRT ENR100 - ENR120 Fgure 1. Examle of CA Dslay ENR G40 CNF Ths secton also descrbes how CA functon detects otental conflcts. The conventonal CDM s dvded nto 2 tyes; one s LP-CDM (Lnear Predcton - Conflct Detecton Method) and the other s FP-CDM (Flght Plan - Conflct Detecton Method). A. LP-CDM Fg. 2 shows a concet of LP-CDM. As LP-CDM assumes that arcraft contnue to fly wth constant seed, redcted t s gven by oston ( ) x and v x v (t = + τ ). (1) ; Poston and velocty of arcraft LP-CDM executes the checks of (2) and (3) for all the arcraft combnatons (, j) n tme t, where tme τ changes n 0 τ T. If both (2) and (3) are satsfed, LP-CDM regards the stuaton as a conflct. 2 ( ) + x ENR A G40 CNF xj z 2 ( y yj ) Rh zj Rv (2) (3)

3 ( ) =, (4) x y, In terms of LP-CDM on RDP, observed oston of arcraft s used as x and estmated velocty of arcraft by trackng observed ostons wth alha-beta flter s used as v. [15] Predcton tme s 3 mnutes, horzontal detecton threshold T Rh s 5 NM, and vertcal detecton threshold Rv s 700 ft f alttude s below 41,000 ft and 1,600 ft f alttude s above 41,000 ft. z Arcraft ostons and veloctes (ground seed and true track angle) measured by arborne sensors are recorded n flght recorded data. Udate rate of them s contnuously 1 second n case of new arcraft tyes. Fg. 4 shows the tracks of arcraft flyng from Haneda arort to Fukuoka arort n Jaan. The ma s lane-rojected centerng Tokyo Area Control Center. In Fg. 4, arcraft fly to turn around arorts. Far from arorts, arcraft almost fly straghtly. The horzontal arcraft rofle was analyzed. Horzontal and Vertcal Sacng < Thresholds Fukuoka Haneda Predcted Postons by Current Postons and Veloctes Fgure 2. LP-CDM Concet B. FP-CDM Fg. 3 shows a concet of FP-CDM. In comarson wth LP-CDM, FP-CDM uses flght lan nformaton. Flght lan s submtted to ATS (Ar Traffc Servce) rovder before dearture. The route where arcraft s gong to fly s ncluded n flght lan nformaton. FP-CDM checks whether or not arcraft are flyng on the lanned route. If arcraft s flyng on the route, FP-CDM extends the redcton course along the route. When the route bends, the redcton course bends at wayonts. On the other hand, f the arcraft sn t flyng on the route, FP-CDM s equal to LP-CDM. Lnear Predcton Predcton wth Flght Plan Fgure 3. FP-CDM Concet Planned Route IV. ANALYSIS ON PREDICTION ERROR OF POSITION In order to understand CDM well, redcton error of arcraft oston on (1) usng flght recorded data were comared wth that usng radar data. In ths secton, we dscussed horzontal and vertcal redcton errors searately. A. Horzontal Predcton Error Observed ostons of arcraft and estmated veloctes of arcraft by trackng observed ostons on the ground sde are recorded n radar data. Udate rate of them for en route survellance n Jaan s 10 seconds. Fgure 4. Arcraft Tracks Horzontal redcton error of oston s defned as E h ( X ( t + T ) ) 2 + ( X ( t + T ) ) 2 =. (5) x x X x ( t + T ) and X y ( t + T ) are horzontal comonents of arcraft oston X ( t + T ) n flght recorded data. x and y are horzontal comonents of redcted oston where τ T = 3 mnutes. = Ground seed ndcates the absolute value of horzontal arcraft velocty and ts unt s knot (1 knot = 1,852/3,600 m/s). Arcraft flght hases based on ground seed are classfed nto acceleraton, constant seed and deceleraton hases. True track angle ndcates the argument value of horzontal arcraft velocty and ts unt s degree. True North s 0 degree and ostve rotaton s clockwse. Arcraft flght hases based on true track angle are classfed nto straght and turn hases. Horzontal comonents of velocty ( vx, v y ) are combned wth ground seed v v x y GS and true track angle GS = GS π 2 Cos TTA y π π Sn TTA 2 π y TTA by. (6) Fg. 5 shows horzontal redcton errors of oston usng radar data and flght recorded data. Calculaton tmng s 10 seconds accordng as udate rate of radar data. Horzontal redcton error of oston usng flght recorded data s reduced n comarson wth that usng radar data. In straght

4 hase, t s reduced by 37 % on average (from 1.43 NM to 0.92 NM). In turn hase, t s reduced by 28 % on average (from 6.51 NM to 4.67 NM). When redctng horzontal arcraft ostons, t s mortant to use arborne velocty (ground seed and true track angle) and to determne adequately whether arcraft flght hase s n straght or turn. hase. Otmzed vertcal rate n clmb and descend hase s smoothed for redcton. Fgure 7. Alttude Vertcal Rate Vertcal redcton error of oston s defned as Fgure 5. Horzontal Predcton Error B. Vertcal Predcton Error Observed alttude of arcraft and estmated vertcal rates of arcraft by trackng observed alttude on the ground sde are recorded n radar data. Udate rate of them for en route survellance n Jaan s 10 seconds. Arcraft alttude and vertcal rates measured by arborne sensors are recorded n flght recorded data. Udate rate of them s contnuously 1 second n case of new arcraft tyes. Fg. 6 shows the alttude from clmb through cruse to descend. The vertcal arcraft rofle was analyzed. z ( t T ) ( t + ) E v X ( t + T ) =. (7) z X + s vertcal comonent of arcraft oston X T n flght recorded data. z are vertcal comonents of redcted oston where τ = T = 3 mnutes. Fg. 8 shows the vertcal redcton errors of oston usng vertcal rate of radar data and otmzed vertcal rate. Calculaton tmng s 10 seconds accordng as udate rate of radar data. Vertcal redcton errors of oston usng otmzed vertcal rate n clmb and descend hases s reduced n comarson wth that usng raw vertcal rate. Standard devaton of vertcal redcton error s reduced by 23 % (from 1,500 ft to 1,150 ft). z Fgure 6. Arcraft Alttude Fg. 7 shows the vertcal rate of alttude. Vertcal rate n cruse hase s constantly 0 ft/mn, and vertcal rate n clmb and descend hases has some fluctuatons. In Fg. 7, otmzed vertcal rate by alha-beta flter n clmb and descend hases are shown. Flter gan α s 0.05 ( β = ), ntal values are 3,000 ft/mn n clmb hase and -3,000 ft/mn n descend Fgure 8. Vertcal Predcton Error In Fg. 8, there are large vertcal redcton errors at the changes of arcraft flght hase such as from clmb to cruse n case of both usng raw and otmzed vertcal rate. Ths means that t s mossble to redct the change of arcraft flght

5 hases by only LP-CDM. To reduce ths vertcal redcton error, t s necessary to use selected alttude bult nto LP-CDM. V. ANALYSIS ON CA OCCURRENCE In ths secton, we menton how CA occurrences were analyzed to understand CDM well. [16] A. Smulaton Condtons We smulated CA occurrences n the current oeratonal envronment. Ar traffc scenaro was made from radar data and flght lan data of Tokyo Area Control Center. Ar traffc volume conssted of 1 hour on the eak of ar traffc. The number of total arcraft was 409. The condtons of conflct detecton were also decded wth reference to oeratonal system arameters. Horzontal threshold Rh was set as 5 NM. Vertcal threshold Rv was bascally set as 700 ft and as 1,600 ft n case that alttude was over 41,000 ft. B. Results TABLE I shows the number of CA occurrence by smulaton. The number of CA occurrence by LP-CDM and FP-CDM were 135 and 109 resectvely. Ths number ncluded the lural tmes caused by the same arcraft ar. 84 and 77 ars of arcraft made all CA occurrences by LP-CDM and FP- CDM. 30 and 21 ars of all made more than 2 tmes of CA occurrence. Fgure 9. Frequency of CA Duratons Fgure 10. Frequency of CA Intervals LP-CDM FP-CDM TABLE I. NUMBER OF CA OCCURRENCE All Only 1 Tme More than 2 Tmes Occurrences (60 %) Pars (36 %) Occurrences (49 %) Pars (27 %) In Fg. 11, attern s strongly domnant at alttude dfferences Conversely, at alttude dfferences 0-, 3 atterns, and are the majortes. In addton, attern rarely occurs. Fg. 9 shows that the frequences of CA duratons by LP- CDM and FP-CDM are the same trends as both 75 % of CA occurrences by LP-CDM and FP-CDM erssted for 0-20 seconds. Fg. 10 shows that the frequences of CA ntervals by LP-CDM and FP-CDM also are the same trends as 71 % and 59 % of CA occurrences by LP-CDM and FP-CDM resectvely reeated every 0-20 seconds, n terms of more than 2 tmes of CA occurrences. Consderng the results of Fg. 9 and Fg. 10, ntermttent CA mght often occur n the conventonal CDM. Fg. 11 shows the classfcaton of vertcal stuatons at the tme of CA occurrence. Vertcal axs reresents the number of arcraft ar. 0- stands for alttude dfferences between 0 ft and 5,000 ft. 50- stands for alttude dfferences between 5,000 ft and 10,000 ft stands for alttude dfferences above 10,000 ft. 3 left-hand bars are made from LP-CDM and 3 rghthand others are made from FP-CDM. Deendng on vertcal flght hases of arcraft at the tme of CA occurrence, vertcal stuatons are classfed nto 6 atterns; the combnatons of clmb, descend and cruse. LP-CDM FP-CDM Fgure 11. Classfcaton of Vertcal Stuatons We counted the number of vertcal maneuvers by checkng the tracks of arcraft ars at the tme of CA occurrence. Vertcal maneuver doesn t stand for that ar traffc controller ssued any nstructons and vertcal maneuver was lanned n advance. The result s summarzed n TABLE II. The numbers are categorzed by alttude dfferences at the tme of CA occurrence. Percentages stand for the numbers dvded by the number of arcraft ar whch s 84 by LP-CDM or 77 by FP-

6 CDM. TABLE II ndcates that vertcal maneuver rarely occurs at alttude dfferences 100- n case of both LP-CDM and FP- CDM. The majortes of vertcal maneuver are consderably connected wth the 3 atterns ncludng cruse hase. LP-CDM FP-CDM TABLE II. NUMBER OF VERTICAL MANEUVER Vertcal Maneuvers,, Vertcal Maneuvers,, (19 %) (10 %) (0 %) (12 %) (6 %) (0 %) (19 %) (12 %) (1 %) (17 %) (6 %) (1 %) Consderng the results of Fg. 11 and TABLE II, when there s such a large alttude dfference as more than 10,000 ft, vertcal maneuvers are rarely observed. Therefore, CA occurred n such stuaton are regarded as to be unnecessary and should be suressed. VI. EVALUATION OF DAPS-CDM Ths secton dscusses the characterstcs of the new DAPs- CDM and descrbe that the results of smulaton verfy the effectveness of DAPs-CDM ntroducton. A. Characterstcs of DAPs-CDM The characterstcs of DAPs-CDM are exlaned below by comarng wth the characterstcs of the conventonal CDM. They are to redct arcraft ostons by usng arcraft velocty of DAPs and to determne arcraft flght hases by usng roll angle and selected alttude of DAPs. TABLE III summarzes the characterstcs of DAPs-CDM. dfferent ont of DAPs-CDM from the conventonal CDM s to use arcraft velocty (ground seed, true track angle, vertcal rate) of DAPs nstead of velocty of radar data. Ths arcraft velocty can be otmzed for redcton by smoothng. When determnng arcraft flght hases, the absolute value of roll angle on the arborne sde s newly used n the horzontal detecton. Selected alttude on the arborne sde nstead of assgned alttude on the ground sde s also used n the vertcal detecton. Roll angle s sometmes called as bank angle because of standng for the amount of arcraft bank. Selected alttude stands for the control target of alttude. DAPs can reflect the latest and more accurate state and ntent of arcraft. Therefore, DAPs-CDM could reduce redcton error of oston caused by fluctuatons of arcraft velocty. In addton, t could redct the change of arcraft flght hases earler and arcraft ostons more close to actual arcraft trajectores. B. Evaluaton of DAPs-CDM Introducton For the urose of comarng DAPs-CDM wth the conventonal CDM, ENRI develoed CDES (Conflct Detecton Evaluaton System). It can smulate both DAPs- CDM and the conventonal CDM under ar traffc stuatons and system arameters as almost same as oeratonal ones. We evaluated the effectveness of DAPs-CDM ntroducton by comuter smulaton. To smulate the envronment where arcraft arameters can be downlnked, flght recorded data ncludng all necessary DAPs were used. Ar traffc volume conssted of 2 hours on the eak of ar traffc. The number of total arcraft was 575 and 22 arcraft of them had DAPs caablty. Calculaton tmng s 10 seconds accordng as udate rate of radar data. Horzontal threshold R h was set as 5 NM. Vertcal threshold R v was bascally set as 700 ft and as 1,600 ft n case that alttude was over 41,000 ft. TABLE III. THE CHARACTERISTICS OF DAPS-CDM LP-CDM DAPs-CDM Remarks Poston x Observed Poston by Radar No Dfference Velocty v Horzontal Flght Phase Determnaton Vertcal Flght Phase Determnaton Estmated Velocty Varaton of Velocty Assgned Alttude GS, TTA Vertcal Seed, Roll Angle Selected Alttude Possble to be Otmzed for Predcton Straght or Turn Clmb/Descend or Cruse on Predcton Lne In DAPs-CDM, Predcted oston s calculated by (1) as LP-CDM and redcton course of arcraft tracks s bended by deendng on flght lan nformaton as FP-CDM. The Fgure 12. Snashot Examle when Smulaton Executed As a result, when comarng the number of CA occurrence usng DAPs-CDM wth that usng the conventonal CDM, there were the dfference n 10 occurrences of CA. In all cases of them, the stuaton was that one arcraft had DAPs caablty and another ddn t. Addtonally, the usage of selected alttude made large dfferences of CA occurrence.

7 Fg. 13 and Fg. 14 show the effectveness of DAPs-CDM esecally n usng selected alttude to determne vertcal flght hases. Fg. 13 shows the CA occurrence not usng DAPs- CDM and Fg. 14 shows that usng DAPs-CDM. Red and blue lnes reresent alttude. Only arcraft colored by red has DAPs caablty and ts selected alttude s reresented by green lne. The tme when CA was detected was lotted by crcle onts on the lnes. In Fg. 14, CA occurrences around 01:45 and 01:50 are not detected by usng DAPs-CDM. Maybe, safety searatons had already been set before 01:45 and 01:50. Because selected alttude reflects the latest and more accurate arcraft ntent, t s very effectve to leverage t roactvely; e.g. when checkng the agreement wth assgned alttude on the ground sde. Alttude [ft] Alttude [ft] 30,000 25,000 20,000 15,000 10,000 5, :40 01:45 01:50 01:55 02:00 Tme [hh:mm] Fgure 13. CA Occurrence not to Use Selected Alttude 30,000 25,000 20,000 15,000 10,000 5,000 0 Arcraft Arcraft j Arcraft Arcraft j 01:40 01:45 01:50 01:55 02:00 Tme [hh:mm] Fgure 14. CA Occerrence to Use Selected Alttude VII. CONCLUSION Selected Alttude The urose of ths study s to develo the new DAPs- CDM and evaluate the effectveness of ts ntroducton by comuter smulaton. Frst, n order to understand the characterstcs of the conventonal CDM, we calculated horzontal and vertcal redcton errors of arcraft oston. Both horzontal and vertcal redcton errors usng flght recorded data were reduced n comarson wth that usng radar data. Horzontal redcton error was reduced by 37 % on average n straght hase and reduced by 28 % on average n turn hase. Standard devaton of vertcal redcton error s reduced by 23 %. It was found better to smooth vertcal seed for redcton and to utlze selected alttude n DAPs-CDM. Then, we analyzed CA occurrences by the conventonal CDM. Intermttent CA mght often occur n the conventonal CDM. When there was such a large alttude dfference as more than 10,000 ft, vertcal maneuvers were rarely observed. Therefore, CA occurred n such stuaton were regarded as to be unnecessary and should be suressed. Fnally, the characterstcs of DAPs-CDM were studed and the results of smulaton whch verfy the effectveness of ts ntroducton were demonstrated. The characterstcs of DAPs- CDM are to redct arcraft ostons by usng arcraft velocty of DAPs and to determne arcraft flght hases by usng roll angle and selected alttude of DAPs. As a result, when comarng the number of CA occurrence usng DAPs-CDM wth that usng the conventonal CDM, there were the dfference n 10 occurrences of CA. We found that the usage of selected alttude made large dfferences of CA occurrence. ACKNOWLEDGMENT We make an address of grateful thanks to all the concerned eole wth ths study. REFERENCES [1] ATCA-J (Ar Traffc Control Assocaton - Jaan), Introducton of Ar Traffc Control, [2] NTT DATA Cororaton, and JCAPF (Jaan Cvl Avaton Promoton Foundaton), RDP System Overvew, [3] JCAB (Jaan Cvl Avaton Bureau), and JCAPF, Basc Research Reorts on Internatonal Trend of SSR Mode S n FY 2002, [4] A. Senoguch, and Y. Fukuda, Study on Conflct Detecton Method wth Downlnk Arcraft Parameters, Electronc Navgaton Research Paers, No. 122,.39-51, [5] ICAO, Procedures for Ar Navgaton Servces - Ar Traffc Management, Doc ATM/501, (12-13), [6] EUROCONTROL, STCA & ACAS Interacton and Interoerablty Worksho Reort,. 11, [7] EUROCONTROL, Secfcaton for Short Term Conflct Alert, [8] EUROCONTROL, Gudance Materal for Short Term Conflct Alert Aendx A: Reference STCA System, [9] Councl of Euroean Unon, Euroean Ar Traffc Management Master Plan, edton 1-30, [10] ICAO, Annex 10 to the Conventon on Internatonal Cvl Avaton Volume IV (Survellance Radar and Collson Avodance Systems), [11] EUROCONTROL, Mode S Enhanced Survellance - 3 States Project - Master Plan, [12] T. Koga, SSR Mode S related researches n ENRI, EIWAC (ENRI Internatonal Worksho on ATM / CNS) 2009, , Mar [13] Mnstry of Transort, Whte Book of Transort, Vol. III, Chater 3, Secton 1, [14] NTT DATA Cororaton, and JCAPF, Grafcal Leaflet of RDP,.202, 1997 [15] G. V. Morrs, Arborne Pulsed Doler Radar, Artech House, Norwood, [16] A. Senoguch, and Y. Fukuda An Analyss on Intermttent Conflct Alert for Ar Traffc Control, Proceedngs of 2008 KSAS-JSASS Jont Internatonal Symosum on Aerosace Engneerng, , 2008.