the ads-b impact over atm concepts (2012)

7/28/2019 The ADS-B Impact Over ATM Concepts (2012)

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162 Int. J. Aviation Management, Vol. 1, No. 3, 2012

Copyright 2012 Inderscience Enterprises Ltd.

Advanced air traffic management technologies:the ADS-B impact over ATM concepts. The case forPortugal

Cludia V.C. Rodrigues, Jorge M.R. Silva*and Kouamana Bousson

Department of Aerospace Sciences,University of Beira Interior,6200-358 Covilh, PortugalFax: + 351-275-329-768 E-mail: [email protected]: [email protected] E-mail: [email protected]*Corresponding author

Abstract: ADS-B is a very useful system to solve surveillance precisionproblems mainly if installation, operation and maintenance costs of alternativeones are too expensive when they are based on air traffic figures. This paperbegins with some remarks about ADS-B technology, precisely to introduce thecase study of Azores archipelago within Santa Maria FIR, in Portugal. On thebasis of real scenarios of Pescara, Trabzon and Rhodes, and using EMOSIAmodel, a study is conducted to understand costs and return on investment onsuch equipment in Azores area. Finally, the paper concludes with somehighlights of future research.

Keywords: automatic dependent surveillance broadcast; ADS-B; CNS/ATM;

Santa Maria FIR; Portugal.

Reference to this paper should be made as follows: Rodrigues, C.V.C.,Silva, J.M.R. and Bousson, K. (2012) Advanced air traffic managementtechnologies: the ADS-B impact over ATM concepts. The case for Portugal,Int. J. Aviation Management, Vol. 1, No. 3, pp.162180.

Biographical notes: Cludia V.C. Rodrigues joined the University of BeiraInterior (UBI) in 2004. She has a graduation on Aeronautical Engineering since2008 with specific knowledge on aerodynamics, flight mechanics, aircraftproject, propulsion, and gas dynamics. Also, she has an MSc on AeronauticalEngineering since 2010 with a dissertation about the impact in Portugal of theautomatic dependent surveillance broadcast (ADS-B).

Jorge M.R. Silva was Merchant Marine Officer in Sociedade Portuguesa de

Navios-Tanque, Lisbon in 19791988, Aeronautical TelecommunicationsTechnician in Aeroportos e Navegao Area, Lisbon in 19881995, Lecturerin 1995 and Assistant Professor since 2005 in the Department of AerospaceSciences, University of Beira Interior, Covilh, Portugal. He has a graduationon Marine Systems Engineer for Electrical and Telecommunications fromEscola Nutica Infante D. Henrique, Oeiras, Portugal in 1993, MSc onOperational Research and Systems Engineering from Instituto SuperiorTcnico, Lisbon in 1996, and PhD on Transportation from Instituto SuperiorTcnico, Lisbon in 2005. His main interests include air transport managementand economy, aircraft operations, air transport safety and security. He is amember of American Institute of Aeronautics and Astronautics (AIAA).


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Advanced air traffic management technologies 163

Kouamana Bousson received his MEng in Aeronautical Engineering from the

Ecole Nationale de lAviation Civile (ENAC) in 1988, MSc in ComputerScience with emphasis on artificial intelligence from Paul Sabatier Universityin 1989, and PhD in Control and Computer Engineering from the InstitutNational des Sciences Appliques (INSA) in 1993, all in Toulouse, France. Hewas a Researcher at the LAAS Laboratory of the French National Council forScientific Research (CNRS) in Toulouse, from 1993 to 1995, and has been aProfessor in the Department of Aerospace Sciences at the University of BeiraInterior, Covilh, Portugal, since 1995. His current research activities includetrajectory optimisation and guidance, optimal flight control systems, analysisand control of uncertain dynamical systems.

This paper is a revised and expanded version of a paper entitled Advanced airtraffic management technologies: the ADS-B impact over ATM concepts. Thecase for Portugal presented at 14th Air Transport Research Society WorldConference (ATRS), Porto, 69 July 2010.

1 Introduction

As air traffic is always growing the need to avoid collisions between aircraft became eachday and even more a very important issue. In this context standard values betweenaircraft were established and called separation minimum. These separations are appliedand verified by air traffic controllers (ATCs) using different control methods asprocedural or non-procedural, e.g., using primary surveillance radar (PSR), secondarysurveillance radar (SSR), multilateration or automatic dependent surveillance (ADS)systems (Figure 1). Also, these methods are used to avoid collisions between aircraft

themselves on the ground or between aircraft and other vehicles within the manoeuvringarea of the aerodrome.

Figure 1 Different types of surveillance sources


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164 C.V.C. Rodrigues et al.

The aeronautical authorities established separation standards to ensure a safe navigation

in controlled airspace. So they can assure that an aircraft is at a safe distance either fromland or from other aircraft.

Nowadays, the large majority of control units (area traffic control centres and towers)uses surveillance sources (rather than procedural methods based on pilot reports toestimate the aircraft position) with less accuracy getting information from PSR and/orSSR. So as PSR tracks only represents targets when they reflect radio waves this meansthat there is a large number of limitations with this technology. Nevertheless, the SSRuses the transponder replies to obtain information about aircraft position andidentification.

There are different radar types accordingly to the area to be covered. En-route radarshave a low update rate (approximately 12 seconds) but cover a large geographic area.Terminal radars cover a much smaller area, in general only the airport and nearby ones,

yet have a much higher update rate (approximately 4.2 seconds). This happens mainlybecause aircraft flying speeds are much smaller in the vicinity of an aerodrome than whenen-route, and thus they can fly closer to each other. This means more aircraft in the samevolume of space so that ATC needs to implement a more precise surveillance system andradar displays needs a higher update rate of refreshments. Also both PSR and SSR needheavy infrastructures and requiring to be placed where there are no considerable obstaclesin quite large vicinity to assure a 360 line-of-sight with aircraft. Maintenance is also akey issue too as these systems have a large number of moving mechanical components.

Multilateration is a surveillance technique where the signals emitted for an aircraft orvehicle on the ground is received by several ground sensors in its vicinity. Thetransponder signal, transmitted in 1,090 MHz and as a result of a set of interrogations ofat least one emitting antenna obligatorily existing in the area to be covered, is received byat least four sensors placed in the vicinity. The main processor based on the calculation ofrelated time difference of arrival (TDOA), that is, small time differences in the signalreception by the involved sensors, esteems aircraft position (NAV Portugal, 2007).Comparing among three receivers/sensors the arrival time of data processor calculates 2Dposition of the aircraft which thus can be used for monitoring ground manoeuvres withinan airport. To get the third parameter (altitude) it is necessary to have at least four sensorsthus getting 3D position of the aircraft. In practice for surveillance either on ground or inflight more than three antennas are used to get bigger redundancy and to allowmonitoring simultaneously several aircraft.

In summary, the total cost of these infrastructures is quite considerable which makesits installation and operation worthwhile only when air traffic volume is justifiable. Soremote areas, small islands or oil rigs, despite having some traffic may not justifyinstalling such a costly system. In these scenarios surveillance is based on procedural

methods with large separations of the aircraft to maintain safety levels. Consequently, theamount of traffic using the same airspace at a given moment is small which contributes toflight operations inefficiency: departure and arrival trajectories, increased holding times,flight level changes (whether is to reduce fuel consumption, to fly at levels with morefavourable winds, or to leave the ones with headwinds or turbulence) are just someexamples.

The idea behind the implementation of an automatic dependent surveillance broadcast(ADS-B) system is that several safety and efficiency benefits can be attained withoutprevious radar coverage (Howell et al., 2010) as key (technical) elements of thesurveillance are the global navigation satellite system (GNSS) and the aeronautical


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telecommunication network (ATN) (Oliveira et al., 2009). To fight against those

mentioned inefficiencies the Federal Aviation Administration (FAA) has embarked on abroad-reaching effort called the next generation air transportation system (NextGen)which seeks to transform todays aviation airspace management and to ensure increasedsafety and capacity precisely using ADS-B technology as an important tool (Boci et al.,2010). There are some reasons to believe in the broad acceptance of this system as, forexample: it uses the 1090 extended squitter (1090ES) technology in use already byMode S transponder, and it get some improvements impacting directly on its groundinfrastructure (Garcia and Gilbert, 2010).

2 Automatic dependent surveillance (ADS-B)

2.1 Technical remarks

In this context we introduce the ADS-B. This surveillance system is based on the abilityof the aircraft to periodically and automatically broadcast a set of data. These data can bereceived either by an ADS-B ground station (ADS-B OUT application) or by an aircraft(ADS-B IN application). It is automatic because there is no need of human (crewmember) intervention, dependent because data broadcasted is based on onboardequipment (like SSR depends on onboard transponders), and broadcastbecause data issent without previous interrogations either by air traffic controller or by any other partner.Its principle is to send as many reports as possible to a greater number of receptors ableto capture its signal.

Nevertheless as aircraft non-equipped with transponders cannot be detected by traffic

alert and collision avoidance system (TCAS), and thus avoiding collisions, as withADS-B system. If an aircraft is broadcasting ADS-B data but traffic in signal range is notproperly equipped, this means that this is not able to receive and process the related data.The conclusion is that the system will produce major benefits as all aircraft, or those in alarge percentage, are equipped with ADS-B avionics.

The technology adopted for ADS-B data transmission in Europe is the 1090 MHZextended squitter, a part of Mode S transponder. When equipped with 1090ES aircrafttransponders are able to receive and broadcast a set of data such as position, speed andintentions in the Mode S signal, without any interrogation by a SSR on ground, or aTCAS when installed onboard. ADS-B exchanging of data does not interfere with TCASinformation too.

The implementation plan for this system is ongoing with a collaborative participationof many stakeholders from air navigation service provider (ANSP) to airline operators,since voluntary (giving advantage to those ones who are just equipped) till mandatoryphases. Thus, Figure 2 represents the capabilities enabled with this system.

Broadcast data has at least the following five information (Eurocontrol, 2008a)packages: aircraft horizontal position; aircraft barometric altitude; aircraft identification;urgency/emergency indicator; and IDENT a special position indicator (SPI).

Concerning onboard avionics the most remarkable improvement is the cockpit displayof traffic information (CDTI). This is the equipment where ADS-B data is displayedto the pilots (Figure 3). The CDTI gives information of relative altitude, trafficidentification and track. Studies about onboard surveillance applications show that CDTI


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in the same display of TCAS it is possible and it is not confuse for pilots if were used

distinguished symbols (Lester and Hansman, 2007).

Figure 2 The ADS-B system

Source: Lester and Hansman (2007)

Figure 3 Cockpit display of traffic information

Source: Lester and Hansman (2007)

Some important advantages are expected when compared with others surveillancesystems (Figure 4) as, for example:

small ground stations, with relatively easy installation procedures and littlemaintenance works


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data is very precise, as it derive directly from onboard systems (GPS-based ones)

update rate of approximately 0.5 seconds, much higher than conventional radars

no significant changes concerning actual avionic sets (using Mode S transpondersextended squitter)

no problems as the conventional radars ones (silence cones and areas, garbling,interferences, etc.)

relatively cheap solution to provide a good surveillance system in areas where thehigh price of installing a SSR/PSR equipment do not justify it, or where there isalready a surveillance source but some redundancy is still necessary

ecological benefits by reducing CO2 emissions, as ADS-B allows easy and fast flightlevel (FL) transitions to those where fuel consumption is more efficient.

All the above mentioned benefits will impact directly on: the airline operators who willbe able to provide better services achieving better flight profiles, and reducing fuelconsumption; theANSPs who will be able to provide better services at a lower cost perairspace user; and thegeneral public due to lower CO2 emissions.

Figure 4 Expected improvements and benefits with ADS-B

Source: Adapted from Song et al. (2007)

2.2 Applications

ADS-B has different applications depending on what it is used for and where it issupposed to be implemented. Thus, there are two main applications: ground surveillanceand airborne surveillance. Ground surveillance is related with ADS-B data received byground stations (ADS-B OUT) and can be divided in: ADS-B NRA, for non-radar


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airspace; ADS-B RAD, for radar airspace; ADS-B APT, for airport surface; and ADS-B

ADD, data derived from aircraft is to be used by ground tools (e.g., selected altitude,climb rate). Airborne surveillance is related with ADS-B data received from other aircraft(ADS-B IN) and this application is called air traffic situational awareness (ATSAW) too.This is divided in: ATSA SURF, for operations on the airport surface; ATSA AIRB, forflight operations when the equipment is installed onboard; ATSA ITP, for IN-Trailprocedures; and ATSA VSA, for visual separation operations.

In this context the European Organization for the Safety of Air Navigation(EUROCONTROL) define the CASCADE programme (Co-operative ATS throughSurveillance and Communication Applications Deployed in ECAC European CivilAviation Conference) which coordinates the implementation of ADS-B applications inEurope (Figure 5).

Within CASCADE there are several initiatives named co-operative validation of

surveillance techniques and applications (CRISTAL) which provide data from validationtrials testing this new technology both in simulators and in real scenarios with a specialattention in the so called pocket areas where operational needs are increasing. Therelated main actors are local ANSPs, airline operators, and aeronautical industry partners.As main outcomes one expects a qualitative and quantitative evaluation of the benefits,effectiveness and safety resulting from the introduction of ADS-B in ATC scenarios.Thus, a huge amount of data will support the production of certification standards andguidance material for flight crews, ATCs, maintenance staffs, among several others.

Figure 5 ADS-B applications in Europe

Source: Adapted from Rekkas (2009)


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Figure 6 Santa Maria FIR and TMA

Source: Adapted from AIP Portugal (2008)

These nine islands are divide in three groups accordingly with their proximity: west(Corvo and Flores islands), central (Faial, Pico, So Jorge, Graciosa and Terceiraislands), and east (Santa Maria and So Miguel islands).

The main traffic axes operating in Santa Maria FIR are: Europe-Caribbean, IberiaPeninsula-North America and Europe-Azores. Regional traffic comprises inter-islandsone and almost 90% is operated by SATA, a regional operator.


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The airspace outside TMA is called oceanic, with a procedural control based on flight

plan tracks updated by position reports (either by voice or ADS-C) complemented with awind grid. TMA control is a mix of procedural and radar, in this particular since radarcoverage is possible.

The single radar antenna in Santa Maria covers east and central groups although inthis one there are a lot of gaps due to islands mountains. West group is completely out ofradar coverage. This results in the application of TMA separation standards, which aresignificantly higher than radar separations, where radar coverage does not exist or isunreliable. Thus, several problems are noticed on air traffic control (NAV Portugal,2007) precisely due to such poor surveillance coverage: departure and arrival flighttrajectory inefficiencies in some islands of the central group; ground delays; verticalflight inefficiencies; and increased holding times.

Accordingly with Eurocontrol (2006) in the 20052025 period air traffic in

Santa Maria FIR is expected to grow between 3% and 4% (Figure 7). But this rate maynot be achieved unless the above mentioned inefficiencies are mitigated or enhanced.

Figure 7 Air traffic average annual growth rates in Europe, 2025/2005 (see online versionfor colours)

Source: Eurocontrol (2006)

To achieve this goal, e.g., in order to enhance surveillance in the central group, anADS-B ground station has to be implemented joining WAM still under installation, andSSR in operation since October 2006. Multilateration (WAM) system is a quite cheapsolution to provide surveillance data without major avionics investments or procedureschanges. Also it can be used either as a transition technology to ADS-B or to addredundancy in surveillance data after full implementation of ADS-B. In Azores, WAMground stations to cover the above mentioned area are those shown in Figure 8.


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Figure 8 WAM ground stations in Azores

Source: NAV Portugal EPE (2010a)

Eleven antennas are planned for Azores. Some of them will act just as receivers whileothers will act simultaneously as receivers and transmitters thus permitting to receiveADS-B reports as well as transponder data. With the introduction of an ADS-B systemthe expected covered area will be that of Figure 9.

Figure 9 Expected covered area with both ADS-B and SSR systems


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Figure 11 Actual (NOTMA) and future (SOLGI) Faial routes to Terceira

Source: Adapted from AIP Portugal (2008)

Figure 12 Scenarios around Picos island mountain (see online version for colours)

3.2 Future expansion

Depending on the performance of this implementation another ADS-B ground station canbe installed in Flores island thus resulting, together with WAM/ADS-B systems in central


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group and SSR radar in Santa Maria island, in a full coverage of Santa Maria TMA,

almost reaching surveillance coverage, at FL300, of New York FIR (Figure 13).

3.3 Costs and returns on investment

We based our cost analysis on data obtained from three examples: Pescara (Italy),Rhodos (Greece), and Trabzon (Turkey). Of course there are other places where ADS-Bwas applied but these ones already have a published cost-benefit report which, althoughyet not validated, can provide us an overall scenario of the global costs for the Azoreaninitiative. Besides the airspace characteristics of those examples are similar than that ofour case study: Trabzon and Pescara have similar airspaces without radar surveillancesource and therefore using procedural separation methods; on the other hand Rhodos hassurveillance radar for FL155 and below but needs to increase their surveillance accuracy;

all of them have to implement some sort of surveillance system to accommodate thegrowing amount of traffic expected for the next future; both Trabzon and Pescara goal isto replace procedural control; for Greece the objective is to improve surveillance sourcefor Rhodos and to replace procedural control for Kos and Karpathos areas.

Figure 13 Coverage with both ADS-B ground stations and SSR radar

Source: Adapted from NAV Portugal EPE (2010b)

These examples can provide a good scenario for initial and reocurrent costs for Azorestoo where there is a mix of all situations in addition with WAM system (not included inthe present study). Also based on Eurocontrol (2006) statistics in the 20052025 periodair traffic annual growth rates for these examples are expected to vary between 1.8% to2.2% in Pescara, 2.2% to 2.8% in Trabzon, and 2.0% to 2.5% in Rhodos against 3% to4% in Santa Maria FIR. Thus, in the next future the volume of air traffic in each thoseplaces can be estimated using the average of such rates, that is: 2.0% for Pescara, 2.5%for Trabzon and 2.25% for Rhodos.


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Figure 14 displays air traffic growth forecasts calculated for Pescara, Trabzon and

Rhodos, as well as for Azores (this one at an average annual growth rate of 3.5% asmentioned in the text and shown in Figure 7).

Costs are mainly of two types, initial and reocurring divided by two entities,Operators and ANSPs, as shown in Figure 15.

Figure 14 Air traffic growth forecasts, 2025/2008, calculated for Pescara, Trabzon, Rhodos andAzores

Figure 15 Initial and reocurring costs for operators and ANSPs

Source: Adapted from Lester and Hansman (2007)


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Within this paper we used estimated costs for the following variables: purchase of the

equipment; installation and commissioning of all infrastructures; ATCs and technicalstaff training; and annual maintenance. Therefore, based on Table 1 (costs per item), totalcosts related to our three examples (Pescara, Trabzon, and Rhodos) are those of Table 2.

Table 1 Costs per item, in millions

Low Medium High

ADS-B equipment purchase 0.1000 0.1250 0.1550

ADS-B equipment maintenance (p/year) 0.0000 0.0020 0.0030

Maintenance staff (p/year) 0.0040 0.0060 0.0080

Technical staff training 0.0050 0.0080 0.0100

ATC training equipment 0.0030 0.0040 0.0050

ATC staff training 0.1920 0.2400 0.2880CWP 0.0050 0.0150 0.0200

Software update 0.0080 0.0100 0.0120

HMI 0.0050 0.0750 0.1000

Communications equipment 0.0050 0.0075 0.0100

Ground ADS-B stations (number of) 1 2 3

Source: Adapted from Eurocontrol (2007b, 2008c, 2008d)

Table 2 Costs for Pescara, Trabzon, and Rhodos, in millions

Initial Reocurrent

Pescara 0.733 0.036

Trabzon 0.689 0.026Rhodos 0.363 0.008

Source: Adapted from Eurocontrol (2007b, 2008c, 2008d)

In this context there is a European model just for analysis of strategic ATM investmentscalled EMOSIA. It uses as inputs the above mentioned variables purchase of theequipment, installation and commissioning of all infrastructures, ATCs and technicalstaff training, and annual maintenance as well as expected movements, to calculate thereturn on such investments (RI). Thus, incorporating on EMOSIA both estimated airtraffic movements and initial/reocurrent costs the returns on investment calculated(Eurocontrol, 2007b, 2008c, 2008d) for 12 years (a general well accepted temporalscenario for investment purposes) for Pescara, Trabzon and Rhodos are those of

Figure 16.Figure 16 RI calculated (12 years) for Pescara, Trabzon and Rhodos

Source: Based on Eurocontrol (2007b, 2008c, 2008d)


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Based on the above mentioned data we can calculate the return on investment (RI) for the

Azorean case also taking into account several variables as airspace characteristics,equipment required, and human resources involved. So surpassing for the Portuguesecase we can esteem (within a low cost scenario) that costs for the implementationof a similar surveillance system with only one receiving antenna will be between0.363 million 0.733 million whereas the reocurrent ones will be between0.008 million 0.036 million. Since acquisition costs of an antenna-radar are higher(4,160 million) than the acquisition ones of an antenna-ADS/B (0.100 million),(Airservices Australia, 2007), and since the maintenance costs (0.210 million) of anantenna-radar are also higher (less than 0,002 million for those of an antenna-ADS/B) itis clear that since the beginning ADS-B alternative has lower total cost than those of anantenna-radar and aiming at the same goal: to improve surveillance in Azores centralgroup.

Therefore, and since our three examples have similar characteristics of Azores airtraffic patterns, based on the above mentioned EMOSIA model results we esteemed theRI for our particular case as follows:

( * )(1) 7.94 M

RI Pescara Azores MovementsRI

Pescara Movements= =

( * )(2) 3.59 M

RI Trabzon Azores MovementsRI

Trabzon Movements= =

( * )(3) 6.31 M

RI Rhodos Azores MovementsRI

Rhodos Movements= =

That is:

(1) (2) (3)

3

RI RI RIRI Azores

+ +=

Thus, having in account:

a an annual (20082025) average growth rate of air traffic of 3.5% within the area

b the installation of one antenna-ADS/B

c human resource costs, the return on investment for Azores for 12 years (a generalwell accepted temporal scenario for investment purposes, as mentioned above) willbe that of Figure 17.

Figure 17 Return on investment calculated for 12 years for Azores

This result can be interpreted as a major return for a minor investment. If it includesadditional benefits as environmental ones and safety improvements the overall outcomecan be even better.


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NAV Portugal EPE (2010a) Navegar, II srie, No. 11, NAV Portugal EPE, Lisbon.

NAV Portugal EPE (2010b) Multilateration and ADS-B program/activities, NAV Portugal EPE,Lisbon.

Oliveira, I., Vismari, L., Cugnasca, P., Camargo, J., Jr, Bakker, B. and Blom, H. (2009) A casestudy of advanced airborne technology impacting air traffic management, in Weigang, L.,Barros, A. and Oliveira, . (Eds.): Computational Models, Software Engineering andAdvanced Technologies in Air Transportation: Next Generation Applications, ISBN: 978-1-60566-800-0, pp.177214, IGI Global, Hershey.

Rekkas, C. (2009) ADS-B deployment plans in Europe ATC global, Eurocontrol, Amsterdam.

Song, J., Oh, K., Kim, I. and Kim, S. (2007) Preliminary implementation of ground-to-groundsurveillance test-bed based on ADS-B concepts, International Conference on Control,Automation and Systems, Seoul.

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