法国预测与国际信息中心-航空服务协议、连通性和排放 Air Service Agreements,Connectivity and Emissions

No2026-04–March

WorkingPaper

CEpii

AirServiceAgreements,

ConnectivityandEmissions

LionelFontagné,CristinaMitaritonna,GianlucaOrefice

&GianlucaSantoni

Highlights

ThesignatureofAirServiceAgreements(ASAs)allowsairlinestoreshapetheinternationalroutenetworkinamoreefficientwayandultimatelyreduceCO2emissionsperpassenger.

UsinguniquedataonairlineticketsandASAsinforceduringtheperiod2012-2019,weshowthatthere-

organizationofinternationallightroutesinducedbyASAsreducesCO2emissionsperworkerby3.9%.

Thecounterfactualanalysissuggeststhatafurtherliberalizationoftheairservices,inwhichallcountrypairs

wouldbelinkedfullliberalizationASAs,wouldimplya2.3%reductioninemissionsperpassenger.

RESEARCHANDEXPERTISE

ONTHEWORLDECONOMY

CEPIIWorkingPaperAirServiceAgreements,ConnectivityandEmissions

Abstract

Theaverageenergyefficiencyoftheaviationsectorhasincreasedby2.7percentperyearsince2012,fallingshortofthe6percentincreaseindemand.Optimizingroutesbyreducingthenumberoflegsperlightisonewaytocomplementtechnologicaladvancesinaircraftandfuelstoreduceaviation'senvironmentalfootprint.ThesignatureofAirServiceAgreements(ASAs)allowsairlinestoreorganizetheirlightroutes.TheyreshapetheinternationalroutenetworkinamoreefficientwayandultimatelyreduceCO2emissionsperpassenger.Ontheotherhand,ASAsincreasethedemandforinternationallights,whichmayoffsetthereductioninoverallCO2emissionsbyairlines.UsinguniquedataonairlineticketsandASAsinforceduringtheperiod2012-2019,weshowthattheconsiderablereductioninper-passengerCO2emissionsduetothere-organizationofinternationallightroutesinducedbyASAsisovercompensatedbytheadditionaldemandforlesstime-consumingand,hence,morecomfortableinternationallights.

Keywords

AirServiceAgreements,AirTransportation,Environment.

JEL

F13,L93,F64.

WorkingPaper

CEpii

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RESEARCHANDEXPERTISE

ONTHEWORLDECONOMY

3

CEPIIWorkingPaperAirServiceAgreements,ConnectivityandEmissions

2

1.Introduction

Theprovisionofairserviceshasbeenshowntoafecttheeconomiclandscape,facilitatethedevelopmentofinterconnectedgeographicareas,andencourageface-to-facerelationshipsthatsupportbusinessrelationships,internationaltrade,andeventechnologytransfer(

Baharetal.

,

2023

;

BlonigenandCristea

,

2015

;

CampanteandYanagizawa-Drott

,

2018

;

Cristea

,

2011

;

HovhannisyanandKeller

,

2015

;

Söderlund

,

2023

).Hence,reducingfrictionsthathinderthesupplyofinternationalairservicescanbebeneficialforcountries.Atthesametime,similartothecaseofinternationaltrade,theenvironmentalimpactofairtrafficcanbedividedintotechnical,scale,andcompositionefects(

CopelandandTaylor

,

1993

;

GrossmanandKrueger

,

1993

;

Shapiro

,

2025

).AirtrafficliberalizationviaAirServiceAgreements(ASAshereafter)isexpectedtohave:(i)atechnicalefect(moreefficientroutes,fewertake-ofsandlandingsasopposedtoconnectinglights),(ii)ascaleefect(increaseddemandforshorterlights)and(iii)acompositionefect(increaseddemandforlong-distanceinternationallightsversusdomesticorshort-distancelights,andredistributionofmarketsharesamongairlines).Understandingtheenvironmentalimpactofairserviceliberalization(ASAs)thereforerepresentsapolicy-relevantquestionthatremainsunderexploredintheacademicliterature.

Inthispaper,wetacklethisquestionandshowhowASAs,bypromotingdirectlights,shapethecarbonemissionsfootprintofairtravel.Todoso,wecombinegranulardataonpassengerticketsfrom2012to2019,lightroutes,thenumberoflegs,andairportlocationswithex-haustiveinformationonAirServiceAgreementsandadetailedsimulatorofaircraftemissions.Oureconometricapproachreliesonbothdiference-in-diferencestechniquesandtheeventstudyapproachtotesttheparalleltrendassumption.Bycontrollingforanycountry-yearandcountry-pairfactorsafectingbilateralairservices,aswellasforanyairline-specifictechnolog-icalandproductivityshocks,wecanclaimcausalityintheimpactofASAsoninternationallightdistance,legs,and,hence,emissionsperpassenger.Thereduced-formeconometricanalysisalsoinformsabouttheefectofdiferenttypesofASAs(dependingontheirdetailedcontent),showingthatfull-liberalizationagreementsaremoreefectiveinreducingemissionsperpassenger.Ourpolicyimplicationsarebasedonacounterfactualanalysisthatreliesonastructuralgravityapproach.Itaccountsforindirectefectsdrivenbythecomplexinterac-tionsbetweentheefficiencyofairlinesandcustomerdemandforairtransportservices,andquantifiestheoverallefectofASAsonemissionsperpassenger.

Thereduced-formeconometricanalysispointstosomeclear-cutresults:signinganASAre-ducesthedistancebetweenoriginanddestinationby1.6percent,thenumberoflegsby3percent,andtheemissionsperpassengerby2.8percent.However,thecontentofASAsmat-ters:signingafullyliberalizingASAreducesemissionsperpassengerby5-6percent,whilesigninganot-fullyliberalizingASAhasnostatisticallysignificantimpactonemissionsperpas-senger.ThecounterfactualanalysissuggeststhattheimpactoftheexistingnetworkofASAsisa1.9percentreductioninemissionsperpassenger,resultingfroma2.8percentincreaseinthenumberofpassengeranda0.9percentincreaseintotalCO2emissions.However,afurtherliberalizationofairservices,inwhichallcountrypairswouldbelinkedbyambitious(fullliberalization)ASAs,woulddeliveranother2.3percentreductioninemissionsperpas-senger,a4percentincreaseindemandformorecomfortablelights,

1

andanet1.7percent

1DemandisinluencedbythequaIity(comfortandduration)oflights,butaIsobyticketprices.DirectlightsaregeneraIIymoreexpensiveperkiIometer,asairIinestakeintoaccountpassengers’wiIIingnessto

CEPIIWorkingPaperAirServiceAgreements,ConnectivityandEmissions

4

4

increaseinemissions.Themainmessageofthecounterfactualanalysisisthatthescaleefectsystematicallyovercomesthetechnicalefect.Ontheotherhand,passengerwelfareincreases.

Thispaperbuildsonthreestrandsofliterature.First,discriminationinaccesstointernationalairserviceshasbeenshowntobeamajorobstacletopassengertraffic(

Piermartiniand

Rousová

,

2013

).ThelackofambitionamongseveralASAsandtheirnetworkcomplexityreducetheeconomicperformanceofaircompanies,hindercompetition,andeventuallyincreasetransportationcosts.OpenskiesagreementsandconsolidatedagreementsinspiredbythosesignedbytheEUwouldinduceadditionalpassengertraffic.While

PiermartiniandRousová

(

2013

)relyonagravityequation,cross-sectionaldataonpassengertrafficprovidedbytheInternationalAviationTransportAssociation(IATA),andanindexofthedepthofASAstoassesstheimpactofskyliberalizationontraffic,wecontributebyshiftingthefocustoefficiencyininternationallightnetworkre-organizationandemissions,twokeypolicy-relevantquestions.Thisallowsustoassessthescaleandefficiencyefectsofliberalizationofpassengertransport,andfinally,theenvironmentalimpactofASAs.Thepanelnatureofourdata(i.e.withinidentification),combinedwithspecificinformationontheairlinesprovidingairservices,allowsustostrengthenthecausalinterpretationofourfindingswithrespecttopreviouspapers.

Asecondstrandoftheliteraturereliesondetailedinformationonairtickets,lights,orcardpaymentstoassesstrendsininternationalmobility,travelerconsumptionbehavior,dailyemis-sions,orinternationaltradeattheproductlevel.Monthlydyadicairtrafficdatahelptoexplaintheobservedtrendsinincreasinginternationalmobility(

Gabriellietal.

,

2019

).ThefrequencyofdirectlightsandtheexpansionofairportscauseariseinChinesetravelers’spend-ingabroad,asrevealedbycardpayments(

Ho,Chun-YuandPeng,TingtingandTakayama,

HarukaandXu,Li

,

2024

).Thefrequencyofpassengerlightshelpstoestimatetheimpactofin-personinteractionsontradeattheproductlevel(

Wangetal.

,

2021

).Closertoourstudy,granularinformationonticketsprovidesinsightsintotheefectofparticipatinginCORSIAondailyaviationemissionsindevelopingAsiancountries(

Yanetal.

,

2025

),andonthecon-sequencesoftheintroductionoftheEUETSforaviationonemissionsfromintra-Europeanlights(

FagedaandTeixidó

,

2022

).Wecontributetothisspecificfieldoftheliteraturebycombininggranularinformationonroutesandticketstoestimatethedemandandefficiencyefectsofairservicetrafficliberalization.Thedomesticlegofconnectinglights,whichcon-tributesdisproportionatelytoairlineemissionsinadditiontointernationallights,istakenintoaccount.

3

Athirdstrandoftheliteratureassessestheimpactofdiscontinuityintheprovisionofairtransportservices.

CampanteandYanagizawa-Drott

(

2018

)and

Morales-ArillaandBustos

(

2024

)showthatreducingthediscontinuitiesinairtransportbyopeningdirectroutesforfreightwouldallowcountriestospecializeandtrade,andthatthisdiscontinuityimpactsthelong-termallocationofeconomicactivityinspace.Regulatoryobstaclesthataddtotechnologicalconstraintsexplainthisdiscontinuity,estimatedat6,000miles.Wecontributebycombininggeographicinformationonairportswithcomprehensivedataonthenumberoflightlegsrequiredtocovereachorigin–destinationpair.Thisrepresentsasubstantialcontribution,

payforgreatercomfort.ThepresenceofanASAmay,therefore,ultimatelyresultinunchangedprices(theshorterdistanceorlightdurationiscompensatedbyahigherpriceperkilometer),asshowninTable

A4

intheAppendix.

3Takingdomesticlightsintoconsiderationisalsoimportantforthepropermodelingofourcounterfactualanalysis.

CEPIIWorkingPaperAirServiceAgreements,ConnectivityandEmissions

7

5

asitallowsustoexplicitlyaccountforthecomplexnetworkofdirectandindirectlights.Moreover,wefocusspecificallyontheadditionaldemandforpassengertransportservicesinducedbymoreconvenientconnectionsandprovideacounterfactualanalysisshowinghowthecontentofASAsafectsthescaleandefficiencyefectsofderegulation.

Theremainderofthepaperisorganizedasfollows.Section2presentsthedata,providesdescriptivestatistics,anddiscusseshowwecomputedtheemissionsperpassengerbasedontheavailabledata.OuridentificationstrategyisdetailedinSection3.Section4combinestheseelementsandprovidesareduced-formestimationofthedirectenvironmentalimpactofASAs,beforequantifyingthenetefectofASASusingastructuralgravityapproachakintoafull-endowmentgeneralequilibriumtrademodel.Thelastsectionconcludes.

2.DataandDescriptivestatistics

Tostudytheimpactofairserviceagreements(ASAs)onairlinerouteorganization,werequiredetailedinformationonthecontentoftheseagreements,ticketpurchases(includingclass)foreachorigin–destination–yearcombination,anddataonconnectinglights,specificallythenumberoflegsneededtoreachadestinationfromagivenorigin.Tothisend,wecombinethreedetaileddatabases:(i)SABRE,whichprovidesticketinformation;(ii)OpenFlightsAirports,whichgivesthegeolocationofterminalsusedforlights;and(iii)theWorldAirServiceAgreements,whichcontainsthecontentandsignaturedatesofASAs.ThesesourcesaredescribedindetailinSection

2.1

.Afinalkeypieceofinformationconcernsaircraftemissionsoneachroute,bothwithandwithoutconnections,whichweestimateusingasimulatordevelopedatETHZurich.Byintegratingthesevariouselements,wecalculateaverageemissionsperpassengerforeachorigin–destinationpaironeachdate–seethedetaileddiscussioninSection

2.2

.Finally,somedescriptiveevidenceispresentedinsection

2.3

.

2.1.Primarysourcesofinformation

OurprimarydatasourceistheairpassengerdatabaseprovidedbySABRE,acompanythatoperatesacomputerizedreservationsystemwidelyusedbytravelagenciesandairlinestomanagelightbookings.SABREalsocollectsdetailedbookingandticketinginformationfromairlines,whichisusedbythesecompaniestoinformtheirpricingstrategies.Inthisstudy,weutilizethisdatabaseforacademicpurposes.

5

Theversionofthedatabaseusedinthisstudycontainsannualinformationonairpassengertrafficbetween189countriesfortheperiod2012–2019.

6

Thisdatabaseisuniqueintermsofbothcoverageanddataquality.Itprovidesairtransportinformationintermsofrevenueandpassengernumbers,whichallowsustoinfertheaverageticketpriceforlightsbetweentwoairports.Whatmakesthisdatasetparticularlyvaluableforourstudyisthatitrecordstheairlinesellingeachticket,thetypeoflight(directorconnecting),anddetailedinformationonallintermediateconnectinglightsfromtheorigintothefinaldestination,includingtheairportsusedforconnections.Additionally,the

5Thisdatawasaccessedthankstoacollaborationwith,andsupportfrom,theEconomicsofClimateChange,EnergyandTransportUnitoftheDirectorateC-Energy,TransportandClimateoftheJointResearchCentre(JRC)intheframeworkofareporton“Theestimationoftarifequivalentsfortheairservicesector”(JRC/SVQ/2020/LVP/1035).TheJRChadaccesstothecommercialversionofthedatabaseandcarriedoutaninitialaggregationofthegranulardata.

6Wehadaccesstoadatabaseaggregatedbyoriginanddestinationairport,airline,ticketclass,andyear.Inthecaseofmulti-legconnectinglights,wehadthisinformationforeachlegseparately.

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6

databasespecifiestheticketclass(Economy,EconomicPremium,Business,orFirstClass).ThisinformationiscrucialforcalculatingpassengerCO2emissions(seesubsection

2.2

).

Forthebaselineanalysis,weaggregatethedatasetbyyear,countryoforigin,andcountryofdestination,whilekeepingtrackofthenumberoflights(legs)requiredtomovefromtheorigintothefinaldestination.

8

Thisallowsustocomputetheyear-specificaveragedistanceneededtotravelbetweenanytwocountries.Toconstructthismeasure,weusetheOpenFlightsAirportsDatabase,whichprovideslatitudeandlongitudecoordinatesformorethan10,000airportterminalsworldwide.

9

ThedatabasealsoincludesISOcountrycodesandthree-letterIATAairportcodes,whichweusetomergeitwiththeSABREdataset.Additionally,weemploydisaggregated,airline-specificdataandestimatestocontrolforairline-specifictechnologicalshocks(i.e.,fixedefects)whenassessingtheconsequencesofASAs.Thisapproachrepresentsanimportantcontributiontotheexistingliterature.

Ourdistancemeasureisprimarilybasedonthegeodesicdistancebetweenanytwoairports,accountingfortheeventualconnectionsneeded.Hence,thisvariableofdistancevariesde-pendingonthechosenroute,i.e.,diferenthubsfortransitandthenumberoflegs.Bysummingthegreat-circledistancesfromagivenorigintoagivendestinationairportacrossairlinesandtickets,anddividingbythenumberoftickets,weobtaintheaveragedistanceneededtoreachagivendestinationfromagivenorigin.Importantly,sinceairlinecompaniescontinuouslyre-optimizetheirconnectinglightschedules,theaveragedistancevariesovertime.Similarly,wecalculatetheaveragenumberoflightlegsneededtolyfromagivenorigintoagivendestination.

10

Finally,weobtaindataontheAirServiceAgreements(ASAs)fromtheWorldAirServiceAgreements(WASA)database,maintainedbytheInternationalCivilAviationOrganization(ICAO).Thisisthemostcomprehensiveglobaldatabaseofairserviceagreements,containingdetailsofsignatorycountries,thedateofsignature,andthedatetheagreementcameintoforce.However,thisdatabasecomeswithincompleteinformationontheregulationofEU27countries.WefillthisgapbyincorporatingintotheWASAdatabasethesetofregulatoryreformsexperiencedbyEU27countriesinrecentdecades.

11

ThisincludesthefullliberalizationoftheEU’sinternalaviationmarketsince1992,andtheevolutionoftheEU’sexternalaviationpolicysince2002.Indeed,followingtheindicationoftheCourtofJusticeoftheEuropeanUnion(CJEU),anyAirServiceAgreement(ASA)betweenanEUMemberStateandathirdcountrymustgrantequalmarketaccessforroutestodestinationsoutsidetheEUtoanyEUcarrierwithanestablishmentonitsterritory.

12

Asaresult,ASAsbetweenEUMemberStatesandthirdcountrieshavebeenamendedtoincorporatethislegalrequirement.

13

8Wealsoconsiderdomesticlights,assigningASAavalueequaltozero,asdomesticlightsdonotrelyonairserviceliberalization.

9Thedatasetisavailableonlineat

/data.php#country

.

10SABREprovidesdataonthetotalnumberofpassengersforeachpairoforiginanddestinationbyticketclass(economy,economypremium,business,andfirstclass).Thus,theaveragedistanceandnumberoflegsareweightedbythenumberofpassengerslyingineachclass.

11WeareindebtedtoAnaNorman(JRC)forherhelpandguidanceincompletingthisdatabase.

12Thishasbeenimplementedbycountriesintwoways.First,throughindividualbilateralnegotiationsamend-ingorreplacingeachASAseparately(BilateralAirServiceAgreements,BASAs).Second,throughtheEuro-peanCommissionactingonbehalfoftheEUMemberStatesconcerned,negotiatingamendmentsorreplace-mentsformultiplepreexistingbilateralASAswithanon-EUcountryunderasingleframework(HorizontalAgreements,HAs).

13RelevantinformationfromofficialEUsourceswasaddedtotheoriginalWASAdatatoensurecomplete

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7

TheseregulatorychangesinEUairtransportationhaveresultedintheamendmentofnearly914bilateralASAsbetweenEUMemberStatesandthirdcountries.Ofthese,388agreementsweremodifiedthroughBilateralAirServiceAgreementstorecognizethe“Europeannature”ofallEUcarriers,withoutchangingtheoriginalstructureoftheagreements,while511bilateralASAswererenegotiatedasHorizontalAgreementswith36countries.WemergetheamendedWASAdatasetwiththeothertwoprimarydatasourcesusingISOcountrycodes.

Importantly,thankstotheinformationprovidedbytheWASAdatabase,wecanclassifyAirServiceAgreements(ASAs)intotwocategories:(i)FullyLiberalizedAgreements,includingOpenSkiesagreements,and(ii)NotFullyLiberalizedAgreements.TheFullyLiberalizedAgreementscontainatleastfourkeyliberalizationelements:unrestrictedtrafficrights,multi-pledesignationofairlines(withnoroutelimitations),freedeterminationofcapacity(meaningthatairlinesdecidepassengercapacityandlightfrequencywithoutregulatoryrestrictions)anddualdisapprovalorcountry-of-originpricingregimes(allowingairlinestosetfaresfreelywithminimalgovernmentintervention).

15

NotFullyLiberalizedAgreementsdonotincludealltheliberalizationelementslistedabove.

2.2.MeasuringCO2emissionsforaviationpassengers

AcrucialvariableofinterestforourstudyisthelevelofCO2emissionsallocatedtoaviationpassengers:intotal,emissionsperpassenger(EP)andemissionsperpassengerperkilometer(EPKM).Ideally,toaccuratelyestimatethesevariables,wewouldneedtheprecisecharacter-isticsoftheaircraftonwhichpassengersly.Sincethisinformationisnotavailableinourdata,werelyontheestablishedmethodologyemployedbyonlineemissionsimulators.Specifically,wefollowtheapproachdevelopedbytheMyClimateFoundation(

Mylight

,

2024a

).

ThechoicetoadoptMyClimate’scalculatormethodologyisbasedonthreekeyreasons.First,ithasastrongscientificfoundation.MyClimatewasfoundedin2002asaspin-ofofETHZurich,anditsmodelandparametersarebasedonestimatesfromadvancedliteratureandsolidstatisticalanalyzesinthefield.Second,MyClimateprovidescomprehensivedocumentationofthemethodology,ensuringtransparencyandallowinguserstounderstandtheassumptionsanddataunderlyingtheemissionestimates.Third,thismethodologyenablesustocalculatetheemissionsperpassengerwithgreaterprecisionthanotheravailablesimulators,thankstothedetailedleveloflightdatainourdatabase.Forexample,comparedtotheICAOCarbonEmissionsCalculator(

ICAOCarbonEmissionsCalculator

,

2024

)usedby

Yanetal.

(

2025

),MyClimateallowsthecalculationofemissionsconsideringbothdirectlightsandlightswithstopoverswhentravelingfromanorigintoadestination.

16

Furthermore,theparametersofthealgorithmusedtocalculateemissionsvarydependingonthedistancethresholdstraveled.Thosearecrucialaspectsofourresearch.

coverage.AlltheinformationneededtoamendtheWASAdatabasehasbeenrecordedthroughthepublicationsintheOfficialJournal(OJ)oftheEuropeanUnionandvalidatedbyDGMOVE.

15Underthe“dual”or“double”disapprovalmethod,pricesbecomeefectiveunlessbothaeronauticalauthori-tiesdisapproveofthem.Aswiththecountry-of-originapproach(whereeachpartymayapproveordisapproveofpricingonlyforlightsoriginatinginitsownterritory)andthefreepricingmethod,theobjectiveistolimitgovernmentalinvolvementandincreasetariflexibilityfordesignatedairlines.

16AnalternativeistheSmallEmittersTooldevelopedbyEurocontrol,whichisdedicatedtotheairtrafficcoveredbytheEUemissionstradingscheme,i.e.intra-Europeanlights.

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23

8

So,followingMyClimate’smethodology,wecalculatetheCO2equivalentemissionsperpas-sengerinKg,bycabinclass,foragivenlightdistancebetweeneachorigin-destinationairportpairbyapplyingthefollowingformula:

whereSisthenumberofseatsinthelightofagivenhaul(consideringallpassengercate-gories),PLFisthepassengerloadfactor,

18

CFisthecargofactor,

19

CWisthecabinclassweightingfactor,accountingforthediferencesinspaceutilizationandfuelconsumptionperpassengerbasedonseatingclass,

20

EFistheCO2emissionfactorforthecombustionofjetfuel(kerosene),whichis3.16kgCO2eperkilogramofkerosene.

21

Importantly,parametersSandPLFdependonthehaulofthelight:(i)below1500Km;(ii)above2500Km;and(iii)inbetween.

Thesecond-orderpolynomial,ax2+bx+c,fitsthegeneralizedfuelconsumptionfunctionf(x)+LTOforanylightofagivenhaulwithdistancex,whereLTOdenotestheextrafuelusedduringeachlandingandtake-ofcycleaswellasduringthetaxiphase(

Seymouretal.

,

2020

).Sincethesefactorsdiferconsiderablybetweenaircrafttypes,MyClimategathersthenecessaryfiguresforeachvariablefromthe2019globaldataonthemostcommonaircraft.Therepresentative(orstandard)aircraftparametersarederivedbycomputingaweightedmeanacrossdiferentmodels,

22

withseparatecalculationsforshort-distance(x<1500km)andlong-distance(x>2500km)routes.Fortripsspanning1500to2500km,thevaluesaredeterminedusinglinearinterpolation.SeeAppendixTable

A1

formoredetailsontheparametersusedtocalculateemissionsperpassenger.

Allthesevariablesarefinallymergedwithourmaindatabasetoobtainpassengeremissionsforeachpairoforiginanddestinationcountries.Wefirstapplytheformulaineq.(

1

)topassengersbyclass,fromtheoriginairporttothedestinationairport.Forindirectlightswithconnections,theformulamustbeappliedtoeachlegofthejourney.Toobtainthetotalemissionsofpassengerslyin