Interline travel

Interline travel, also called interline ticketing or interline booking, is a commercial and operational arrangement that enables a passenger to travel on an itinerary involving two or more airlines under connected ticketing and handling procedures. It is not a conventional consumer brand or a single airline; rather, it is an industry practice supported by agreements between participating carriers, ticketing systems, travel agencies, settlement organizations, and baggage-handling processes. Under a standard interline arrangement, one airline can issue a ticket that includes transportation provided by another airline. Depending on the agreement, the passenger may be able to check in for the entire itinerary, have baggage tagged through to the final destination, and receive assistance or rebooking if a delay causes a missed connection. The carrier that issues the ticket is commonly known as the plating or issuing carrier. It collects the passenger's fare and taxes, while the airlines that operate individual flight segments receive their allocated portions through industry settlement processes. Interline agreements may be unilateral or bilateral. A unilateral agreement allows one carrier to issue tickets involving another carrier, while a bilateral agreement permits both airlines to issue tickets on each other's services. The commercial relationship is distinct from code-sharing. A codeshare places one airline's designator on a flight operated by another airline, whereas interlining concerns the ability to sell, ticket, settle, and handle a journey involving multiple carriers. The two arrangements can operate together, because a codeshare itinerary may require interline capability among all relevant marketing and operating carriers before a single ticket can be issued. Historically, interlining was especially associated with large network airlines and international travel. Airline alliances such as Star Alliance, SkyTeam, and Oneworld typically provide extensive interline connectivity among members, although unaffiliated airlines and even direct competitors can also cooperate. Smaller legacy carriers often use interline agreements to connect their local markets with the networks of larger airlines. Many newer low-cost carriers, particularly those that sell primarily through their own websites and do not participate fully in global distribution systems, have traditionally offered limited or no conventional interline capability. The adoption of electronic ticketing substantially broadened participation. The industry-wide move away from paper tickets, including the International Air Transport Association's effort to eliminate paper tickets by the end of 2007, required more carriers to implement electronic ticketing and associated interline processes. Interline transactions generally depend on ticketing and settlement infrastructure such as global distribution systems, the Airlines Reporting Corporation in the United States, the Billing and Settlement Plan in many other markets, and the IATA Clearing House. When no valid interline agreement exists, a passenger normally must buy separate tickets. That arrangement may require collecting and rechecking baggage, clearing immigration or customs again, and accepting responsibility for protecting the connection. If the first flight is delayed, the second airline may have no obligation to provide free rebooking. This distinction is important because online travel agencies sometimes display combinations of separate flights that resemble conventional connections but are not contractually protected as a single interline itinerary. During the 2010s, virtual interlining expanded the concept. Companies such as Dohop and Kiwi assembled separate flight segments from airline booking systems and sold them as combined journeys, sometimes adding missed-connection assistance, accommodation reimbursement, replacement-flight vouchers, or customer support. Virtual interlining generally does not provide the same baggage transfer, transit, or rebooking rights as a conventional interline ticket. Passengers may need to collect and recheck baggage and may have to pass through immigration or leave an airside transit zone. The model is therefore most straightforward in areas with permissive entry rules, including visa-free domestic or regional markets and parts of the Schengen Area. Interlining can also extend beyond airlines. Ferry and bus operators may participate if they obtain appropriate industry identifiers and publish schedules compatible with airline distribution systems. Rail operators have likewise entered intermodal arrangements with airlines; examples cited in industry descriptions include agreements involving ITA Airways, Iryo, and Trenitalia. The overall purpose remains the same: make a journey combining multiple transport operators easier to sell and coordinate, while defining how revenue, passenger service, baggage, and disruption responsibilities are allocated.

Interlining developed as airlines expanded beyond single-route operations and needed mechanisms for carrying passengers across networks operated by different companies. A carrier selling a journey that included another airline's flight required agreements governing ticket issuance, fare allocation, baggage acceptance, passenger handling, and settlement. These arrangements were particularly important for international network airlines, whose schedules could not independently serve every origin and destination. The practice is separate from, but often connected to, code-sharing. Code-sharing concerns the marketing of an operating carrier's flight under another carrier's designator. Interlining concerns whether the airlines can sell and administer a connected itinerary, including the issuance of one ticket and the transfer of relevant passenger and revenue information. An itinerary can therefore involve code-sharing, interlining, both, or neither. Interline agreements can be directional. In a unilateral arrangement, one airline may issue a ticket containing another airline's segment, while the second airline cannot necessarily issue the reverse combination. Bilateral arrangements provide reciprocal ticketing authority. In a typical transaction, the issuing or plating carrier receives the passenger's payment, and the operating carriers invoice or settle for their portions through established airline-industry systems. Travel agencies remit funds through organizations such as ARC in the United States or BSP in other markets, while the IATA Clearing House supports carrier-to-carrier settlement. Large network carriers and members of global airline alliances have historically been the most active participants. Alliance membership normally supports extensive interline connectivity, although interline cooperation does not require alliance membership and may exist between competitors. Regional and legacy airlines use these agreements to feed traffic into larger networks. By contrast, many low-cost airlines have limited participation because they emphasize direct sales, point-to-point networks, and operating models that do not include full-service connecting obligations. Electronic ticketing changed the economics and availability of interline arrangements. The airline industry's transition away from paper tickets, culminating in the IATA electronic-ticketing mandate at the end of 2007, required carriers to adopt systems capable of processing electronic documents across participating airlines. This made interline ticketing more accessible to smaller carriers, although technical, commercial, and distribution constraints continued to limit participation. The absence of an agreement creates a materially different passenger experience. Travelers holding separate tickets may have to retrieve baggage, complete a new check-in, pass through customs or immigration, and bear the cost of a missed connection. Online agencies can sometimes show such combinations as self-transfer or virtual-interline journeys. During the 2010s, specialist platforms including Dohop and Kiwi commercialized virtual interlining by combining separately purchased segments and adding optional or bundled protection services. These products increased the number of theoretically available connections but generally retained the operational risks of separate tickets. Interlining has also expanded into multimodal transport. Ferry and bus operators can participate through industry identifiers and schedule distribution, while rail-air cooperation allows passengers to combine train and flight segments in a coordinated booking environment. Such arrangements reflect a broader movement toward integrating transport networks, although the precise rights and responsibilities depend on the participating operators and the type of ticket issued.

• 2010

  Virtual interlining gains visibility

  [1]Interliningen.wikipedia.org

  During the 2010s, specialist travel companies began packaging separately booked flight segments into virtual interline itineraries, sometimes with missed-connection assistance or other protections.

• 2007

  IATA electronic-ticketing transition

  [1]Interliningen.wikipedia.org

  The industry-wide move to eliminate paper tickets by the end of 2007 required more airlines to implement electronic-ticketing and interline-processing capabilities.

Interline travel functions as interoperability infrastructure for passenger transportation. Its value lies in combining carrier networks, distribution systems, ticketing, baggage handling, and settlement processes into a journey that can be sold and managed across operator boundaries. Conventional interlining offers stronger contractual coordination than self-transfer or virtual interlining, while virtual models emphasize broader route combinations and consumer price discovery.

• Airline ticketing

  Conventional interline ticketing

  A single ticket or electronically coordinated itinerary covering flights operated by multiple airlines under valid interline agreements. Depending on the participating carriers, it can support through check-in, baggage transfer, coordinated fare settlement, and assistance when an airline-caused disruption breaks the connection.

• Travel distribution · 2010

  Virtual interlining

  A journey assembled from separate flight bookings, usually by a travel platform that combines segments from carriers without a conventional interline agreement. Some providers add replacement-flight, accommodation, voucher, or helpline services, but passengers commonly remain responsible for baggage recheck, immigration formalities, and connection risk unless specific protection is included.

• Multimodal passenger transport

  Intermodal air-rail and air-ferry itineraries

  Coordinated journeys combining airline services with rail, ferry, or bus segments. Participating non-air operators may use industry identifiers and distributed schedules so their services can be incorporated into airline-oriented booking and ticketing workflows.

1. 1Interliningen.wikipedia.org