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Codeshare agreement

A codeshare agreement is a business arrangement in the aviation industry in which two or more airlines market and sell seats on the same flight operated by one of the partners. Each airline uses its own IATA two-letter airline designator code (e.g., "AA" for American Airlines) and flight number to identify the service.^[1] The operating carrier physically flies the aircraft and provides the crew, while the marketing carrier or carriers promote the flight as part of their own network, enabling passengers to book through a single ticket even if changing airlines.^[2] This practice, common since the late 20th century, simplifies travel for passengers by allowing seamless connections and baggage handling across partner airlines and has become integral to global airline alliances.^[3] Codeshare agreements originated in the 1960s and expanded significantly after U.S. airline deregulation in 1978, with the term coined in 1989 by Qantas and American Airlines.^[4] They vary in structure and offer strategic benefits to airlines, such as network expansion and revenue sharing, while providing passengers with broader access and loyalty program integration. However, they are subject to regulatory oversight to address competition and consumer protection concerns.^[1]

Introduction to Codesharing

Definition and Core Concept

A codeshare agreement is a business arrangement in the airline industry where one airline, known as the operating carrier, physically operates a flight, while one or more other airlines, referred to as marketing carriers, sell tickets for that same flight using their own flight designator codes.^[1] This allows the marketing carriers to offer the flight as part of their own network, effectively expanding their route offerings without needing to operate the aircraft themselves.^[3] The core purpose of codeshare agreements is to enable airlines to broaden their global reach, share revenue from ticket sales, and enhance passenger connectivity across destinations that might otherwise be uneconomical or logistically challenging to serve independently.^[3] By leveraging each other's strengths, airlines can provide seamless travel options without investing in additional aircraft, crew, or infrastructure, thereby optimizing operational efficiency and market penetration.^[2] In practice, a single flight may carry multiple flight numbers—one from the operating carrier and others from its partners—meaning passengers booking through a marketing carrier might not realize the operating airline until check-in or boarding.^[5] The concept traces its origins to 1967, when Hagerstown Commuter (now part of Henson Airlines) entered the first known codeshare partnership with Allegheny Airlines, allowing the smaller carrier to feed passengers into the larger network under a shared code.^[6] Unlike interlining, which involves basic coordination for baggage transfers and connections between separate flights operated by different airlines, codeshares emphasize joint marketing and branding to present a unified service experience.^[5]

Key Terminology

In codeshare agreements, the operating carrier is the airline responsible for physically operating the flight, including providing the aircraft, crew, maintenance, and ensuring compliance with safety regulations.^[1]^[7] The marketing carrier, by contrast, is the airline or airlines that place their designator code on the flight, market and sell tickets for it, and share in the revenue without handling the actual operation.^[1]^[2] A key element is the flight code, an alphanumeric identifier (such as AA123) assigned by the marketing carrier to the operating carrier's flight, allowing passengers to book and travel under the marketing carrier's branding while the flight is executed by the partner.^[1]^[8] Blocked space agreements refer to arrangements where the marketing carrier pre-purchases or reserves a fixed block of seats on the operating carrier's flight, managing its own inventory and booking classes independently from the operating carrier's remaining capacity.^[2] Revenue sharing in codeshare agreements typically follows proration models outlined in IATA standards, such as multilateral or special prorate agreements, where fares are divided based on predefined percentages or proportional to sectors flown.^[9]^[7] A common method is the mileage prorate, which allocates revenue proportionally to the distance covered under each carrier's code relative to the total journey distance; for instance, if the marketing carrier's coded segment is 500 miles out of a 1,000-mile total fare journey, its share would be calculated as:

\text{Revenue Share} = \left( \frac{\text{Marketing Carrier's Coded Distance}}{\text{Total Journey Distance}} \right) \times \text{Total Fare}

This formula ensures equitable distribution based on operational contributions, often adjusted through IATA clearing processes post-flight.^[9] Additional terms include the prime flight, which denotes the original flight operated and marketed solely by one airline without any codeshare overlay, serving as the base for partner codes.^[10] A ghost flight, in this context, refers to a codeshare leg that operates without prominent branding from the marketing carrier, appearing primarily under the operating carrier's identity to passengers.^[11]

Historical Context

Origins in the 1960s-1980s

The origins of codeshare agreements trace back to the United States in the late 1960s, when regional carriers sought ways to integrate with larger trunk airlines to expand their reach on short-haul routes. The first known codeshare arrangement was established in 1967 between Henson Aviation, operating as Hagerstown Commuter from Hagerstown, Maryland, and Allegheny Airlines, a regional predecessor to US Airways. Under this agreement, Henson operated feeder flights to Allegheny's hubs using the larger carrier's flight designator code, allowing seamless ticketing and baggage transfer for passengers on regional U.S. routes such as Hagerstown to Washington, D.C. This pioneering partnership marked an early form of network integration, predating the formal term "codeshare" and enabling smaller operators to leverage the branding and distribution of established airlines.^[6] The U.S. Airline Deregulation Act of 1978 played a pivotal role in accelerating the adoption of such arrangements by dismantling government controls on fares, routes, and market entry, which intensified competition and prompted airlines to form cooperative strategies for survival and growth. Post-deregulation, smaller and regional carriers increasingly turned to codeshares to access the extensive networks and reservation systems of major airlines, thereby enhancing connectivity without the need for independent long-haul operations. This shift was particularly beneficial for commuter airlines, which could offer passengers the appearance of a single-carrier journey while sharing revenues and operational responsibilities. By the early 1980s, these agreements had become a common tool for U.S. carriers to optimize capacity and market presence in a deregulated environment.^[12]^[4] In Europe, adoption of similar cooperative models remained limited during the 1960s and 1970s, largely due to the prevalence of state-owned flag carriers and rigid bilateral air service agreements that prioritized national monopolies over inter-airline partnerships. Major airlines like British Airways and Air France operated under government oversight, which discouraged revenue-sharing arrangements that could undermine sovereign control of routes. However, initial bilateral discussions on enhanced cooperation began emerging in the late 1970s, influenced by growing pressures for market liberalization within the European Economic Community. A notable early experimentation occurred in 1985 with the first international codeshare between American Airlines and Qantas on trans-Pacific routes, which introduced cross-border elements and paved the way for further global trials, including transatlantic partnerships. Although the specific term "codeshare" was not yet in use— it was coined in 1989 during negotiations between Qantas and American Airlines— these precursors laid the groundwork for formalized global agreements by the end of the decade.^[13]^[14]^[4]

Expansion in the 1990s and Beyond

The expansion of codeshare agreements gained significant momentum in the 1990s, driven by the formation of major global airline alliances that positioned codesharing as a foundational element of their cooperative strategies. The Star Alliance, the first such network, was established on May 14, 1997, by founding members Air Canada, Lufthansa, Scandinavian Airlines System (SAS), Thai Airways International, and United Airlines, enabling extensive codeshare operations across their combined route networks to enhance global connectivity without equity investments.^[15] This was followed by the launch of oneworld on February 1, 1999, initiated by American Airlines, British Airways, Cathay Pacific, and Qantas, which similarly relied on codeshares to offer passengers seamless itineraries spanning multiple continents.^[16] SkyTeam entered the landscape in June 2000, with initial partners Air France, Delta Air Lines, Aeroméxico, and Korean Air formalizing codeshare arrangements to expand their reach, particularly in transatlantic and transpacific markets.^[17] A pivotal regulatory development occurred in 1993 when the U.S. Department of Transportation (DOT) granted the first antitrust immunity for an international codeshare to Northwest Airlines and KLM Royal Dutch Airlines (Order 93-1-11), setting a precedent for future partnerships by allowing coordinated pricing and scheduling without violating competition laws. The American Airlines-Qantas codeshare agreement, initiated in 1990 following its 1989 negotiation, later received antitrust immunity in 2019 to expand into a full joint venture, facilitating integration of Australian and U.S. routes.^[18] This approval facilitated the integration of Australian and U.S. routes, paving the way for broader alliance-based codeshares. The global proliferation continued with Asian carriers, exemplified by Cathay Pacific's 1998 codeshare pact with American Airlines, which extended to intra-Asian and U.S. domestic services and marked a key step in oneworld's Asian expansion.^[19] In Latin America, integrations accelerated in the early 2000s, notably with LAN Chile (now part of LATAM) joining oneworld in 2000, enabling codeshares that connected South American hubs to North American and European networks.^[20] By 2010, codeshare agreements had proliferated to encompass thousands of routes worldwide, supporting the three major alliances in serving over 1,000 destinations collectively and contributing substantially to airline revenues through expanded sales without additional aircraft deployment.^[21] This growth was bolstered by technological advancements, particularly the widespread adoption of global distribution systems (GDS) such as Sabre and Amadeus in the 2000s, which integrated airline inventories to enable real-time, seamless booking of multi-carrier itineraries across travel agent platforms.^[22] These systems reduced operational friction, allowing passengers to purchase codeshare tickets as single transactions and airlines to optimize load factors on partner-operated flights.

Strategic Benefits

Advantages for Airlines

Codeshare agreements allow airlines to expand their networks by providing access to additional routes and destinations operated by partner carriers, without the need to invest in new aircraft or infrastructure. This enables carriers to offer feeder traffic to their hubs from remote or low-demand locations, effectively creating a seamless "from anywhere to anywhere" service model. For instance, through alliances like Star Alliance, major carriers can connect passengers across a vast global network, with immunized alliances accounting for over 80% of transatlantic and transpacific capacity as of the early 2010s.^[21] These partnerships enhance revenue generation by increasing passenger traffic volumes and optimizing load factors—the percentage of seats filled on flights—through shared inventory and fare combinability. Airlines can sell seats on partners' flights, boosting overall capacity utilization without proportional increases in operating expenses; conceptually, this improves effective capacity as the sum of an airline's own seats plus codeshare seats divided by total flights operated, leading to higher yields on partnered routes. Empirical studies show that airlines with more code-sharing partners, particularly within the same alliance, experience positive associations with profit margins, as seen in analyses of 81 carriers from 2007 to 2012.^[23] Cost savings arise from shared resources, such as joint marketing campaigns, ground handling, and distribution channels, which lower per-passenger expenses on collaborative routes. By leveraging partners' existing operations, airlines avoid the sunk costs of entering thin markets independently, reducing overall operating expenditures while maintaining service levels. For example, codeshares on low-volume international routes, like those between Australia and Pacific islands, allow carriers to allocate seats efficiently without dedicating full aircraft.^[24] In terms of competitive positioning, codeshare agreements strengthen airlines' global reach through multilateral arrangements in alliances, enabling them to compete more effectively against non-partnered rivals. A notable recent case is the codeshare between Eurowings (Lufthansa Group) and SunExpress (a Lufthansa-Turkish Airlines joint venture) within the Star Alliance ecosystem, launched in July 2025, which enhances connectivity in the Germany-Türkiye market and signals warming relations.^[25]^[21] Finally, codeshares mitigate risks by distributing exposure across partners' networks, particularly during periods of fluctuating demand or economic downturns. Airlines can gauge market potential on new routes through limited seat allocations before committing to full operations, thereby hedging against underutilization and stabilizing revenue streams in volatile environments.^[24]

Benefits for Passengers

Codeshare agreements provide passengers with seamless connections across multiple airlines through a single booking process for multi-leg itineraries, eliminating the need to reissue tickets or manage separate reservations. This arrangement ensures protected baggage transfer, where luggage is checked through to the final destination without retrieval at intermediate stops, reducing the risk of mishandling and simplifying travel logistics.^[26]^[27]^[21] Passengers benefit from expanded travel choices, gaining access to a broader array of destinations and higher flight frequencies that would otherwise require coordination between non-partner carriers. For instance, through global alliances incorporating codeshares, travelers can reach smaller or regional cities via partner networks, effectively creating a "from anywhere to anywhere" connectivity that significantly increases route options—such as over 300 additional destinations in some partnership examples.^[3]^[21]^[28] Loyalty program integration allows passengers to earn and redeem frequent flyer miles across partner airlines in a unified system, enhancing the value of rewards accumulated from travel. In the oneworld alliance, for example, members can credit miles from flights operated by any of the 15 member airlines to their preferred program's account, facilitating easier status achievement and redemption for awards on codeshare routes.^[29]^[30] These agreements often lead to pricing advantages for passengers, as shared capacity and coordinated pricing foster competition that can lower fares compared to independent bookings. Studies indicate fare reductions of up to 11.6% on codeshare itineraries relative to non-allied interline options, with immunized alliances yielding even greater savings—up to 27% lower than non-aligned routes—due to efficient capacity utilization.^[31]^[21] Additional convenience features include unified check-in at the originating airport for the entire journey and potential access to partner lounges, regardless of the operating carrier, provided eligibility criteria such as elite status or premium cabin booking are met. This streamlines the airport experience, with single ticketing enabling fare combinability and consistent service protocols across codeshare partners.^[21]^[32]^[33]

Varieties and Mechanics

Types of Codeshare Agreements

Codeshare agreements can be classified by their structure and scope, primarily as bilateral or multilateral arrangements. Bilateral codeshares involve two airlines collaborating on specific routes or networks, allowing each to market the other's flights under their own code. For instance, American Airlines and Qantas maintain a bilateral codeshare that enables seamless connections between the United States and Australia on select trans-Pacific routes.^[34]^[35] Multilateral codeshares, by contrast, encompass multiple carriers, typically within global alliances, to create extensive network connectivity; SkyTeam, for example, facilitates such arrangements among its members using a free-flow model for broader route integration.^[35] Another key classification focuses on seat allocation methods, which determine how the marketing carrier accesses inventory on the operating carrier's flights. In block space agreements, the marketing airline purchases a fixed number of seats in advance, such as 20 seats per flight, creating a dedicated inventory separate from the operating carrier's sales.^[36] Free-flow agreements allow the marketing carrier to sell seats dynamically based on real-time availability shared between partners, without pre-allocated blocks, promoting flexibility in high-demand scenarios.^[36]^[2] A hybrid variant, capped free-flow, combines elements of free-flow with protective limits, where the marketing carrier can access seats up to a predefined maximum to safeguard the operating carrier's revenue yield.^[2] These allocation types often intersect with structural classifications; for example, the 2023 Delta Air Lines and airBaltic codeshare partnership operates as a bilateral free-flow arrangement, enabling Delta to place its code on 20 airBaltic routes across the Baltics without fixed seat blocks.^[37]

Operational Implementation

The operational implementation of codeshare agreements begins with detailed negotiations between partner airlines, focusing on key contractual elements such as revenue proration clauses and slot coordination to ensure equitable financial outcomes and operational harmony. Revenue proration clauses outline how ticket revenues are divided between the marketing carrier (which sells the ticket) and the operating carrier (which flies the segment), often using formulas based on distance flown, sector length, or agreed percentages, as specified in special prorate agreements filed with bodies like the Airline Tariff Publishing Company (ATPCO).^[38] Slot coordination involves mutual agreement on flight schedules to optimize airport slot usage, minimize connection times, and maximize passenger convenience, with changes requiring advance notification and publication in global distribution systems (GDS).^[38] These negotiations typically incorporate protections against revenue leakage, such as billing through automated clearing houses for uplifted coupons.^[39] Technical integration follows, relying on International Air Transport Association (IATA) standards to enable seamless code placement in GDS like Amadeus, Sabre, or Travelport. The marketing carrier assigns its two-letter airline designator code (e.g., "AA" for American Airlines) to the operating carrier's flight number in the schedule, creating a unified itinerary visible to travel agents and passengers; this is facilitated through ATPCO filings where operating carriers are specified in flight applications under Category 4 for codeshare routes.^[40] A typical workflow involves the operating carrier providing schedule data via IATA's Standard Schedules Information Manual (SSIM) format, after which the marketing carrier inputs its code into the GDS inventory, updates reservation booking designators (RBDs) for inventory control, and ensures fare rules align with the joint route map.^[41] This process allows the marketing carrier to promote the flight as its own while the operating carrier manages actual operations. Passenger handling protocols emphasize seamless experiences across partner networks, adhering to IATA resolutions for joint check-in and baggage management. At the originating airport, passengers receive a single itinerary ticket, enabling check-in with either carrier for the entire journey, including issuance of IATA-standard automated baggage tags that bear the operating flight designator for codeshare segments to ensure correct transfers.^[42] Baggage is tagged with a ten-digit license plate including the originating carrier's Baggage Tag Issuer Code (BTIC) per Resolution 769, allowing through-checking to the final destination without re-tagging, provided minimum connecting times (MCT) are met under Resolution 765.^[42] The most significant carrier (MSC), determined by Resolution 302, applies its baggage rules, with scanning mandatory at check-in, transfer, and arrival points per Resolution 753 to track and secure luggage.^[42] Data sharing underpins real-time coordination, primarily through application programming interfaces (APIs) and standardized messaging like EDIFACT for inventory synchronization between partners. Marketing and operating carriers exchange seat availability data via APIs to support dynamic inventory models, such as free-flow arrangements where seats are allocated in real time without pre-blocking, ensuring the marketing carrier can sell seats from the operating carrier's schedule.^[2] Challenges arise in yield management, where discrepancies in pricing strategies or inventory controls can lead to overbooking or revenue dilution, as partners must reconcile differing revenue optimization goals while complying with IATA's Passenger Name Record (PNR) standards for synchronized booking data.^[43] Ongoing monitoring involves sharing performance metrics to evaluate agreement effectiveness and compliance, with a focus on operational reliability. Partners track indicators like on-time performance, flight completion rates, and load factors, often incorporating financial incentives or penalties; according to a 2013 U.S. Department of Transportation Office of Inspector General review of 13 agreements, 92% of reviewed U.S. domestic codeshare agreements included bonuses for exceeding 95% on-time targets over multi-month periods.^[44] These metrics are exchanged via joint reporting systems or third-party audits, enabling adjustments to schedules or prorations based on shared data, though oversight bodies like the Federal Aviation Administration (FAA) emphasize reviewing such incentives to mitigate safety risks from performance pressures.^[44]

Regulatory and Competitive Landscape

Antitrust and Competition Issues

Codeshare agreements have raised significant antitrust concerns due to their potential to increase market concentration and reduce competition on overlapping routes. By allowing airlines to coordinate operations and share revenues, these arrangements can effectively eliminate independent competition between partners, leading to higher market shares for the involved carriers. For instance, the U.S. Department of Justice (DOJ) has scrutinized alliances like United Airlines and Lufthansa, noting that antitrust immunity for such codeshares reduces competition on transatlantic routes where partners previously offered rival flights.^[45] In the 2010s, the DOJ and Department of Transportation (DOT) examined the Star Alliance partnership between United and Lufthansa, imposing carve-outs on specific overlapping routes, such as Frankfurt to Chicago, to preserve competitive options.^[45] Consumer confusion represents another key competitive issue, as passengers may be misled by the branding of codeshare flights, resulting in unexpected variations in service levels and amenities. Travelers booking under a marketing carrier's code often assume uniform standards, but the operating carrier may provide different experiences, such as limited baggage allowances or inferior in-flight services, without clear upfront disclosure.^[46] This lack of transparency can distort consumer choice and undermine competition by allowing marketing carriers to leverage their brand without fully bearing the service risks.^[46] Price effects from codeshares further exacerbate competition concerns, with empirical studies indicating potential fare increases through coordinated pricing mechanisms. On U.S. domestic non-stop routes, codeshare agreements have been associated with airfare hikes exceeding 5% due to the "round table" effect, where partners exchange fare information to facilitate tacit collusion.^[47] Additionally, double marginalization in these arrangements can lead to fares nearly 10% higher than those from non-participating airlines on the same routes.^[47] Such pricing coordination on immunized international routes amplifies these impacts, potentially harming consumers by reducing downward pressure on prices.^[45] Globally, regulatory bodies have probed codeshares for similar anticompetitive risks, as seen in the European Union's examination of the SkyTeam joint venture involving Air France-KLM, Alitalia, and Delta Air Lines. In 2012, the European Commission launched an antitrust investigation into their transatlantic revenue-sharing and capacity coordination, citing concerns over reduced competition on key routes between Europe and the U.S.^[48] The probe culminated in 2015 with the acceptance of commitments from the airlines to limit capacity and pricing coordination on three specific routes, ensuring some competitive safeguards.^[49] To mitigate these issues, antitrust authorities emphasize transparency requirements, such as mandating disclosure of the operating carrier in codeshare bookings. In the U.S., DOT regulations require airlines and ticket agents to clearly identify the transporting carrier before purchase, including on websites, to address consumer confusion and promote informed decision-making.^[50] Similar measures in the EU focus on route-specific remedies to balance alliance efficiencies with competitive protections.^[49]

Government Regulations and Approvals

In the United States, the Department of Transportation (DOT) holds primary authority under 49 U.S.C. §§ 41308–41309 to approve international airline alliance and codeshare agreements, granting antitrust immunity to shield them from domestic antitrust laws where necessary to promote competition and consumer benefits.^[51] The Department of Justice (DOJ) provides advisory input on potential anticompetitive effects during the review process.^[45] A notable example from the 2020s is the DOT's July 2025 approval of the transfer of Hawaiian Airlines' international route authorities to Alaska Air Group as part of their merger integration, which facilitated expanded codeshare operations without triggering new antitrust concerns.^[52] In the European Union, the European Commission evaluates codeshare agreements under EU competition law (Articles 101 and 102 TFEU), focusing on their potential to restrict competition, particularly on routes with significant overlaps.^[53] For agreements involving route overlaps, the Commission often requires remedies such as the release of airport slots to competitors to mitigate foreclosure effects and ensure market access.^[54] This approach was evident in cases like the 2016 investigation into the TAP Portugal-Brussels Airlines codeshare, where the Commission alleged anticompetitive coordination on pricing and capacity but closed the investigation in 2018 without requiring commitments, as new airline entry on the route addressed competition concerns.^[55] At the international level, codeshare agreements are facilitated by International Air Transport Association (IATA) resolutions, such as Resolution 780, which establishes the multilateral interline framework for ticketing, baggage handling, and scheduling coordination essential to codeshare operations.^[56] These are further enabled by bilateral air service agreements (ASAs) between governments, which specify permissible codesharing between designated carriers and may impose restrictions on route rights or capacity.^[57] ASAs thus form the foundational legal basis for cross-border codeshares, with IATA standards ensuring operational interoperability.^[58] The approval process for codeshare agreements seeking antitrust immunity typically begins with carriers filing applications with the relevant authority, such as the U.S. DOT, including detailed agreements and competitive analyses.^[51] This triggers a public notice period for comments from stakeholders, often followed by an order to show cause outlining preliminary findings, with opportunities for rebuttals.^[59] The timeline generally spans 6 to 12 months, depending on complexity and comment volume, culminating in a final order granting or denying immunity with any conditions.^[60] Once approved, codeshare agreements require ongoing compliance, including annual reporting to regulators on route performance metrics such as capacity, connectivity, and on-time arrivals, as well as fare monitoring to detect potential price increases beyond industry averages.^[59] In the U.S., DOT mandates periodic audits and self-assessments for immunized alliances, with carriers submitting data on cooperative activities to ensure sustained public interest benefits.^[51] Non-compliance can lead to immunity revocation, as seen in enforcement actions against underperforming joint ventures.^[61]

Broader Applications

Air-Rail and Intermodal Codeshares

Air-rail codeshares represent an extension of codeshare agreements into intermodal transport, where airlines apply their flight designators to rail services operated by partner railway companies, facilitating integrated bookings and travel experiences across air and rail networks. This model enables passengers to purchase a single ticket for journeys that combine flights and trains, often with coordinated schedules to minimize connection times at integrated hubs like airport train stations. Such partnerships have been particularly prominent in Europe, where high-speed rail networks complement short-haul air routes, promoting efficiency and reducing the need for separate reservations.^[62] A seminal example is the collaboration between Lufthansa and Deutsche Bahn, which initiated Lufthansa Express Rail in the late 1990s, building on earlier cooperation to offer coded rail connections from major German cities to Frankfurt and Munich airports.^[63] Under the Rail&Fly program, passengers can travel from any Deutsche Bahn station to international flights up to one day before or after departure, with seamless ticketing and baggage handling.^[64] Similarly, Air France has maintained a 30-year partnership with SNCF, the French national railway, providing Train + Air services on 41 routes connecting TGV high-speed trains directly to Paris Charles de Gaulle and Orly airports since the mid-1990s.^[65] In the United States, United Airlines operated a codeshare with Amtrak until early 2021, allowing integrated bookings between Amtrak trains and United flights at hubs like Newark Liberty International Airport, where rail connections served regional routes.^[66] These intermodal arrangements offer key benefits, including single-ticket journeys that streamline travel and reduce transfer hassles, while enabling passengers to earn airline loyalty miles on rail segments.^[67] In Europe, such codeshares align with broader policy goals for sustainable mobility; for instance, EU Regulation (EC) No 1371/2007 on rail passengers' rights ensures compensation and assistance for disruptions on combined trips, treating through-ticketed intermodal journeys comparably to single-mode travel.^[68] However, implementation faces challenges, particularly in synchronizing train and flight schedules to optimize connections, as misalignments can lead to missed departures and operational inefficiencies.^[69] Additionally, fare proration for non-air segments requires complex interline agreements to equitably divide revenues between airlines and rail operators, often involving intricate billing rules and restrictions on fare validation.^[70] As of 2025, Europe hosts numerous air-rail partnerships, with at least nine major airlines offering integrated services across key airports and high-speed lines, reflecting a trend toward greater intermodality.^[67] These have expanded beyond Europe, with recent developments like Air Canada's 2025 codeshare extension to Deutsche Bahn services via Lufthansa, underscoring ongoing growth in coordinated air-rail networks.^[71]

Recent Trends and Future Directions

The COVID-19 pandemic led to the suspension of a significant portion of global airline operations in 2020, with flight capacity dropping by 80-95% in March and April, resulting in widespread pauses in codeshare agreements to align with reduced schedules and travel restrictions.^[72] As recovery progressed, airlines formed new partnerships to rebuild networks, such as Delta Air Lines and airBaltic's codeshare launched in November 2023, enabling Delta to place its code on 20 routes from airBaltic's Baltic bases.^[37] Post-pandemic, the adoption of digital tools accelerated, including contactless check-in and biometric verification, facilitating seamless codeshare operations by minimizing physical interactions at airports and enhancing passenger confidence in multi-carrier itineraries.^[73] Alliance shifts continued into the mid-2020s, with Scandinavian Airlines (SAS) officially joining SkyTeam on September 1, 2024, expanding the alliance's Nordic coverage and integrating SAS's routes into the global network.^[74] Similarly, ITA Airways exited SkyTeam in February 2025 with a transition period ending April 30, 2025, and began integrating into Star Alliance in April 2025, with full membership expected in 2026 to leverage Lufthansa Group's infrastructure.^[75]^[76] Air India pursued aggressive expansion, announcing plans for over 10 new codeshare agreements in 2025 to enhance connectivity in North America, Europe, and Africa, including deals with Air Astana in September 2025 and Icelandair in June 2025.^[77]^[78]^[79] Expansions like Etihad Airways' strategic codeshare with STARLUX Airlines, signed in June 2025, further connected the Middle East to Taiwan and beyond.^[80] Sustainability has emerged as a key driver in codeshare strategies, with partnerships enabling higher load factors—often increasing by several percentage points through route optimization—which in turn reduce fuel consumption and emissions intensity.^[81] For instance, every 1% rise in load factor can yield approximately 0.83% fuel savings on short- and medium-haul flights, supporting broader efficiency goals.^[82] These efforts align with the International Air Transport Association's (IATA) 2021 resolution for net-zero carbon emissions by 2050, where codeshares contribute by maximizing aircraft utilization and minimizing empty legs.^[83] Technological innovations are enhancing codeshare efficiency, including AI-driven dynamic pricing models that adjust fares in real-time based on demand, weather, and competitor data, as piloted by Delta Air Lines for up to 20% of domestic routes by late 2025.^[84] In free-flow codeshares, where airlines share inventory without pre-allocation, AI facilitates personalized pricing across partner networks to optimize revenue.^[85] Blockchain technology is also advancing secure data sharing, enabling transparent revenue distribution and tamper-proof exchange of flight and passenger information in interline agreements.^[86] Looking ahead, codeshare growth is accelerating in the Asia-Pacific region, driven by rising connectivity demands, as seen in the April 2025 strategic partnership between Qatar Airways and Philippine Airlines, which introduced daily Manila-Doha flights starting June 2025 with mutual codes on onward routes.^[87] This reflects broader trends of increasing airline partnerships in Asia to capture market expansion.^[88] However, potential regulatory tightening on green claims may impact sustainability-focused codeshares, following EU investigations in 2024 that prompted over 20 airlines to revise environmental assertions, such as neutralizing flight emissions, to avoid misleading consumers. In November 2025, 21 airlines committed to changing their practices to comply with EU consumer protection rules.^[89]^[90]^[91]

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List of Active Antitrust Immunized Alliances. Last updated 3/27/2024 (listing of inactive cases). Case Details: Last updated: Friday, May 2, 2025.
[20]
Cathay Pacific: redefining its role - Aviation Strategy
The aim is for Cathay and American to code–share on Hong Kong–US, intra–Asian and some US domestic services, but at present Hong Kong will not accede to US ...
[21]
History - LATAM Airlines
TAM withdraws from STAR ALLIANCE and joins oneworld, becoming the global alliance for LATAM Airlines Group · LATAM launches its 2015-2018 strategic plan, with a ...
[22]
[PDF] the economic benefits generated by alliances and joint ventures - IATA
Nov 28, 2011 · Alliances began as simple code share arrangements, which were little more than enhanced marketing agreements allowing an airline to sell a seat ...
[23]
Online Booking History: CRSs, GDSs, and Online Travel Agenci
Apr 12, 2019 · In the early 2000s, three major global distribution systems (Amadeus, SABRE, and Travelport) took their final form, becoming the biggest ...
[24]
The effect of code-sharing alliances on airline profitability
The profit margin of an airline is found to be positively associated with the number of code-sharing partners it has.Missing: percentage | Show results with:percentage
[25]
Code‐sharing in the airline industry - Wiley Online Library
Oct 29, 2021 · partnerships, that is, by 2010, the number of partners was considered old partners, and the new relations created in 2011, 2012, 2013 and.<|separator|>
[26]
[PDF] Code Sharing in International Aviation: a Discussion Paper
A major incentive for code sharing on US domestic services was provided from the mid-1980s when regulations to deal with display bias on CRSs resulted in online ...
[27]
What A Codeshare Flight Is And Why It Matters To Travelers
Jun 9, 2025 · A codeshare flight is an agreement between airlines to sell seats on each other's flights. This can allow you to flight just about anywhere ...
[28]
Airline alliances: The power players of global aviation - AeroTime
Feb 21, 2025 · Notable examples of successful independent full-service carriers include Emirates, which has access to more than 300 extra destinations through ...
[29]
The Oneworld Alliance: Everything You Need To Know (Partners ...
Aug 25, 2025 · Members can earn and redeem miles across all Oneworld airlines, providing more flexible travel options. ... earn and redeem frequent flyer rewards ...Oneworld Alliance · Oneworld Partners* · Status Equivalents
[30]
Partner airlines - American Airlines
You can earn AAdvantage miles on American and codeshare flights with partner airlines. Partner flights earn miles based on a percentage of distance flown.Missing: example | Show results with:example
[31]
[PDF] On the Efficiency of Codeshare Contracts Between Airlines
Abstract. The literature on the economics of airline codesharing has suggested that codeshare agreements serve to eliminate double marginalization that ...
[32]
https://www.fcmtravel.com/en-us/airline-alliances-codeshares
[33]
Unpacking airline alliances and codeshares - FCM Travel
Shared facilities. Business class lounges, check-in counters, and baggage handling facilities are shared among members of the same alliance. All three airline ...
[34]
Our network and codeshare destinations - Emirates
Existing Emirates benefits and policies extend to Qantas codeshare flights, such as baggage allowances, lounge access and frequent flyer benefits. We ...<|separator|>
[35]
Qantas − Partner airlines - American Airlines
You can earn AAdvantage® miles when you fly on Qantas marketed and operated flights and Qantas codeshare flights operated by Qantas affiliate airline QantasLink ...
[36]
Airline alliances - what future? Global, multilateral and bilateral ...
Dec 17, 2013 · Global alliances often make bilateral codeshare agreements with airlines outside their alliance to expand their network reach. There is a debate ...
[37]
[PDF] Code-share arrangements: A Guide
There are two main types of code-share arrangements: • Block space: The marketing airline buys from the airline operating the flight a specific share of the ...
[38]
Delta and airBaltic launch new codeshare cooperation
Nov 15, 2023 · Delta will add its DL* code to airBaltic flights, providing customers with convenient connections and more flexible booking and ticketing options.
[39]
Codeshare Agreement - SEC.gov
The Parties agree that accepted industry procedures and agreements relating to the interlining of passengers and baggage, including those set forth in IATA ...
[40]
Codeshare and Special Prorate Agreements: An Introduction - IATA
You will learn how to create and negotiate SPA contracts, understand the regulatory environment and develop strategies for protecting revenue while expanding ...Missing: implementation coordination
[41]
[PDF] Partnering for Success: Interline, Code Share, and Alliances - IATA
If you are in a code share agreement: □ Specify operating carriers in Flight Application (Category 4). 4. International Fares. If you choose to file fare ...
[42]
Understanding IATA's SSIM format: A guide for airlines - Cirium
Apr 5, 2023 · IATA SSIM is a standard format that airlines use to exchange flight schedule data with airports, GDSs and other stake holders.<|control11|><|separator|>
[43]
[PDF] Interline Considerations on Baggage Standards - IATA
For codeshare flights, in order to ensure the interline bag is transferred correctly, the tag itself must bear the flight designator (airline designator and ...Missing: joint | Show results with:joint
[44]
[PDF] Codeshare and alliance revenue management best practices
Aug 24, 2012 · In interlining and codesharing, revenue sharing. (or proration) determines how the revenues are divided among the different airlines flown as.Missing: slot | Show results with:slot
[45]
None
### Summary of Performance Monitoring in Codeshare Agreements
[46]
Antitrust Immunity And International Airline Alliances
In 1993, the U.S. and the Netherlands implemented an Open Skies agreement and DOT granted antitrust immunity to Northwest and KLM. Under the terms of this ...
[47]
Growth of Domestic Airline Code Sharing Warrants Increased Attention
Feb 14, 2013 · We also found that some confusion still exists for consumers about which airline is operating their flight because carriers, travel agencies, ...
[48]
The Price-Increasing Effects Of Domestic Code-Sharing Agreements ...
The article identifies an increase in airfares charged by code-sharing partners of more than 5 percent attributable to the “round table” effect. On top of this, ...
[49]
EU probes Air France/Delta transatlantic pacts - Reuters
Jan 27, 2012 · EU antitrust regulators are investigating whether pricing and capacity pacts between Air France-KLM <AIRF.PA>, Alitalia and Delta Air Lines ...
[50]
Antitrust: Commission accepts commitments by SkyTeam ...
May 11, 2015 · The European Commission has adopted a decision that renders legally binding commitments offered by Air France/KLM, Alitalia and Delta, members of the SkyTeam ...
[51]
Airline Passenger Rights: The Federal Role in Aviation Consumer ...
The 1978 deregulation of the airline industry in the United States eliminated federal control over many airline business practices, including pricing and ...
[52]
Alliances and Codeshares | US Department of Transportation
Dec 16, 2024 · US air carriers are required to submit cooperative service agreements that they have with each other, such as reciprocal code sharing, joint frequent flyer and ...
[53]
Alaska Air Group receives DOT approval for transfer of ...
Jul 14, 2025 · The DOT approved on 14 July the de facto transfer of “certificates and other economic authorities” held by Hawaiian to Alaska Air Group, ...Missing: 2020s | Show results with:2020s
[54]
62016TJ0712 - EUR-Lex - European Union
Because of the possible impact of those codeshare agreements on competition on each of the two routes, the Commission considered that the agreements were ...
[55]
competition law and state aid for the aviation sector in European Union
Aug 12, 2022 · The Commission pays particular attention to overlaps on hub-to-hub routes. ... routes where slot remedies are required. These include, for ...
[56]
European Commission cracks down on codeshare agreement ...
Dec 19, 2016 · The Commission is alleging that during the first three years of the 2009 codeshare arrangement, the two airlines pursued an anti-competitive strategy.Missing: slot remedies
[57]
[PDF] Interline Considerations on Irregular Operations (IROPs) - IATA
Jun 25, 2020 · IATA has created a template for bilateral agreements (see Appendix) however airlines can use whatever form of agreement they wish. Upgrading to ...
[58]
Code-share arrangements: A Guide | Canadian Transportation Agency
Jun 18, 2021 · Bilateral agreements say whether airlines from two different countries can code-share and they may set restrictions on these arrangements.
[59]
[PDF] Air Service Agreement Liberalisation and Airline Alliances
The objective of this report is to provide an overview of the key principles and issues underlying bilateral air service agreements (ASAs) and the authorisation ...
[60]
[PDF] GAO-19-237, INTERNATIONAL AIR ALLIANCES
Mar 20, 2019 · 2 Since DOT granted antitrust immunity to the first alliance agreement in 1993,. American, Delta, and United have entered into various immunized.
[61]
Approval of and Antitrust Immunity for Alliance Agreements Under ...
Jun 28, 2022 · The United States Department of Transportation has issued an Order to Show Cause tentatively approving and granting antitrust immunity (“ATI”) ...Missing: DOJ | Show results with:DOJ<|separator|>
[62]
[PDF] Order 2025-7-12 Issued - Department of Transportation
Jul 12, 2025 · Order 2025-7-12 proposes to withdraw approval and antitrust immunity for the Delta/Aeromexico JV due to Mexico's actions reducing competition ...
[63]
Air-rail alliance - Wikipedia
There are four main types of airline-railway business alliance or codeshare agreements: dedicated services, entire network access, Night&Fly, and re-protection ...
[64]
Air–rail timetable synchronisation: Improving passenger connections ...
This paper focuses on optimising the air and rail timetables at 18 major European airports including three hubs and their associated train stations.
[65]
[PDF] Interaction of High-Speed Rail and Aviation - MIT
Germany, was initiated in the late 1990s, building on previous coop- eration between Lufthansa and DB Bahn. The following is a brief timeline and overview ...
[66]
To your flight with Rail&Fly - Lufthansa
Rail&Fly, in cooperation with Deutsche Bahn, allows travel from any German station to/from international flights, including one day before/after, with flexible ...
[67]
Air France broadens 30-year relationship with SNCF - AeroTime
Feb 11, 2025 · This service has been considerably extended in recent years and is now available on 41 routes to and from Paris-Charles de Gaulle and Paris-Orly ...Missing: codeshare | Show results with:codeshare
[68]
United Airlines and Amtrak cutting ties by early 2021 - The Points Guy
Nov 1, 2020 · For years, United and Amtrak have had a codeshare partnership, allowing you to purchase a flight to or from Newark with a connection on the ...
[69]
9 airlines that offer air and rail tickets in Europe - The Points Guy
Mar 6, 2025 · 9 airlines that offer air and rail tickets in Europe · Delta Air Lines' Air + Rail program · United Airlines' train partners · Air France's plane ...
[70]
[PDF] Interpretative Guidelines on Regulation (EC) No 1371/2007 of the ...
Jul 4, 2015 · It aims to protect the rights of rail passengers in the Union, particularly when travel is disrupted, and to improve the quality and ...Missing: integration | Show results with:integration
[71]
Codeshare Flights: Benefits & Challenges - Sciative Solutions
Jul 19, 2024 · 1. Seamless Transfers: One of the primary advantages of codeshare flights is the ease of transferring between airlines, especially when they ...
[72]
[PDF] The Future of Interline A new model for seamless customer journeys
This may include special prorate agreements, Involuntary rerouting agreements, codeshare agreements, selling agreements, interline e-ticketing agreements, and ...
[73]
Air Canada Enhances its Rail Connections in Germany Through ...
Jun 26, 2025 · Air Canada today announced an extension of its codeshare agreement with Lufthansa to include Lufthansa Express Rail services at Frankfurt Airport, operated by ...
[74]
The First 100 Days: How Airlines Responded to the COVID-19 Crisis
on the order of 80–95 percent during the months of March and April ...
[75]
Delivering contactless and low-touch travel around the world - SITA
Oct 27, 2020 · We've helped dozens of airports and airlines deliver solutions allowing them to safely resume flights and get our industry moving again.Missing: codeshares | Show results with:codeshares
[76]
SAS OFFICIALLY JOINS SKYTEAM GLOBAL AIRLINE ALLIANCE
Sep 1, 2024 · SAS has officially joined the SkyTeam global airline alliance today, marking a major milestone for the airline and elevating SkyTeam's global network to new ...
[77]
ITA Airways Has Exited SkyTeam & Joins Star Alliance In ...
Feb 3, 2025 · ITA Airways has today exited SkyTeam, but there will be a transition phase through April 30, 2025, during which most, if not all, existing benefits will be ...
[78]
ITA Airways Set to Start Integration into Star Alliance
Apr 2, 2025 · ITA Airways has officially received approval to start the integration process into Star Alliance following a verdict by the Star Alliance Chief Executive Board ...
[79]
Air India Eyes 10 New Codeshare , Plans Global Expansion
May 21, 2025 · Air India (AI) plans to add over 10 new codeshare agreements in FY25 to expand connectivity across North America, Europe, and Africa.
[80]
Air India and Air Astana enter codeshare partnership
Sep 10, 2025 · The new arrangement builds on an existing interline partnership between Air India and Air Astana that came into effect earlier in 2025.
[81]
A new partnership: Icelandair and Air India
Jun 2, 2025 · On June 2, 2025, we announced our new codeshare partnership with Air India, significantly boosting connectivity between India and Iceland, while ...
[82]
Etihad Airways and STARLUX Airlines sign strategic codeshare ...
Jun 4, 2025 · New Delhi, India - Etihad Airways has signed a strategic codeshare agreement with Taipei-based STARLUX Airlines, expanding customer access ...
[83]
Network ambidexterity and environmental performance: Code ...
Nov 19, 2021 · Such literature has found that code-sharing significantly increases the load factor, that is, the percentage of seats occupied in a plane ( ...
[84]
Analysing the opportunities and challenges for mitigating ...
Based on Morrell's [94] estimations, an 0.83% fuel saving could be achieved with every 1% increase in seat capacity in a short- and medium-haul aircraft.Missing: codeshare | Show results with:codeshare
[85]
Our Commitment to Fly Net Zero by 2050 - IATA
A resolution was passed by IATA member airlines committing them to achieving net-zero carbon emissions from their operations by 2050.Missing: codeshare | Show results with:codeshare
[86]
Delta starting to scale its AI-driven dynamic pricing system
Jul 17, 2025 · Delta Air Lines is pricing about 3% of its domestic fares with an artificial intelligence system and plans to get to 20% by the end of 2025.Missing: codeshares blockchain secure
[87]
Dynamic Pricing in Aviation: How AI is Revolutionizing Airline ...
Dec 5, 2024 · The convergence of AI, machine learning, and real-time data processing completely transforms how airlines approach pricing strategy.Missing: flow codeshares blockchain
[88]
Blockchain Solutions for Airlines | Dalmatian Group
Blockchain enables transparent and auditable revenue sharing between carriers in a codeshare or interline agreement. Real-time ticket tracking; Elimination of ...
[89]
Qatar Airways and Philippine Airlines Announce New Strategic ...
Apr 24, 2025 · From 16 June 2025, Philippine Airlines will offer daily nonstop flights from Manila to Doha in codeshare cooperation with Qatar Airways.Missing: Pacific regulatory tightening
[90]
Partnerships between airlines: the strategy to win the Asian market
By increasing partnerships and alliances, particularly in Asia, they are strengthening their positions while minimizing risks and investments.
[91]
https://www.beuc.eu/press-release/21-airlines-commit-stop-greenwashing-following-beuc-complaint
[92]
Action against 20 airlines for misleading greenwashing pract
Apr 29, 2024 · A concrete step to enhance consumer protection against misleading green claims can also be found in the Directive on empowering consumers for ...