Flying with more than one airline: how interline travel works

What does interline travel mean?

In an interline journey, you hold one ticket, but more than one airline flies you to your destination. One airline might take you from Helsinki to a hub, and a partner airline continues from there.

The point is reach. Airlines connect their networks so you can plan a single trip to destinations far beyond what one carrier serves on its own. You have have one booking reference, and the airlines coordinate your journey between them.

This is different from a codeshare, and we will come back to that distinction below.

How does flying with several airlines work in practice?

Most of an interline trip feels like any other journey. A few details are worth knowing in advance.

Where do you check in? As a rule, you check in with the airline operating the first flight your journey to each direction. If you fly Finnair from Helsinki to a hub and a partner onward, you check in with Finnair. On the way back, you check in with the airline flying the first leg home.

Will you get all your boarding passes at once? Often you will. “In many cases you receive all your boarding passes at check-in, but not always,” says Milla. It depends on the airlines and the airport systems involved, she explains, and the reassuring part is that you can always ask about your boarding passes and your onward journey at the check-in counter.

Do you need to do anything at the airport? Usually, you simply follow the transfer signs to your next gate. If a later airline's boarding pass was not issued online, their check-in or transfer desk will sort it out for you at the airport.

What happens to your baggage?

This is the question travellers ask most, so it is worth being clear.

Is your bag checked through to the final destination? In most interline journeys, yes. Your checked baggage travels straight to where you are going, and you collect it at the end.

There are exceptions. You may need to pick up and re-check your bag if the airlines do not have an interline through check-in (IATCI) agreement, if your flights are on separate tickets, or if local rules such as customs require it. “In most interline travel your baggage is checked through to the final destination, but this is not guaranteed every time,” says Raphael. His advice is simple: you can always confirm it at check-in and by checking your baggage tag.

Whose baggage rules apply? Your baggage allowance follows the airline you bought the ticket from, the marketing airline. The correct allowance is always shown on your ticket, so that is the place to look if you are unsure.

Interline or codeshare: what is the difference?

The two are easy to mix up, and the practical difference is simple to spot.

A codeshare flight is operated by a partner but carries a Finnair flight number. An interline flight is operated by a partner under its own flight number. As a traveller, a codeshare tends to feel more tightly integrated, while interline opens up a wider network of destinations. “The easiest way to tell is the flight number,” says Raphael. If a partner-operated flight has an AY number, it is a codeshare with Finnair; if it does not, it is interline.

Why interline partnerships matter to you?

Alliances alone cannot cover every destination travellers want to reach. Interline partnerships fill the gaps, so you can plan a single trip well beyond Finnair's own network or its alliance. “On its own, the Finnair network is around a hundred destinations. Together with our partners, you can reach more than 1,100,” says Milla. That, she adds, means more choice, easier connections, and the freedom to design a route that suits you.

One ticket also protects you if something disrupts your journey. If your first flight is cancelled and you would miss a later connection because of it, you are rebooked all the way to your destination. You are also looked after during longer disruptions, with meal vouchers or a hotel if it comes to that. "On separate tickets you would not be entitled to any of this," says Milla. "It can mean an unexpected cost, and a lot of stress mid-journey." With one ticket, that side of travel is handled for you.

For you, the journey feels like one trip rather than a set of separate flights, with one booking holding it together.

New journeys that open up

The advantage of interline travel is the map it unlocks. A Finnair long-haul flight can connect you onward to secondary cities you could not reach on a single carrier. For example, you could fly from Helsinki to Los Angeles with Finnair, continue to Tahiti in the Pacific on a partner airline, and return via Tokyo, all on one ticket. A flight to New York can carry on to Nassau in the Bahamas and home through Chicago or Dallas, the kind of journey no single airline maps out on its own.

It also makes stopovers easy to build in. Because the whole route sits on one ticket, you can make planned stopover in a hub city like Tokyo or Los Angeles for a day or two and still keep your onward connection in place. The network does the work in the background, and you get to plan the trip you actually want.

A few things worth keeping in mind

A little awareness goes a long way on a multi-airline trip.

Check your baggage rules before you travel and confirm the through-check at the airport. Allow comfortable connection time between flights operated by different airlines. And remember that not every service carries seamlessly across carriers, so some travel extras may work a little differently along the way.

This is where the most common misunderstanding creeps in. “Customers often assume that because everything is on one ticket, all services are the same from start to finish,” says Milla. Even if there are differences in the service, the journey can still be smooth and connected, she says. Different airlines simply run different parts, so things like baggage handling or loyalty points can work a little differently as you go.

One last question: which interline destinations are at the top of your own list?

Milla would pick Inverness and Aberdeen in Scotland. You can reach each one with several of Finnair's interline partners, so they have stayed on her mind. Raphael would head for Byron Bay in Australia, reached via the nearby Ballina or Gold Coast airports, exactly the kind of multi-airline route that comes together on a single interline ticket.

Plan your multi-airline trip

You can read the full practical details, from check-in to seats and assistance, in our guide to travelling with several airlines. It is the place to check the specifics before you book a route that crosses more than one carrier.