If you've ever seen a PNR with two different airlines on it for what's supposed to be one trip, you've already run into interlining — even if nobody explained the term to you. This guide breaks down what it actually means, how it shows up in a PNR, and why it matters for how you handle a booking.
What Is Interlining?
Interlining is an agreement between two or more airlines that allows them to handle each other's passengers and baggage as part of a single connected journey — even though the passenger is technically flying on separate tickets or carriers for different legs of the trip.
In practice, this means a passenger can book one itinerary that involves, say, an outbound flight on Emirates and a connecting flight on Qantas, with baggage checked through to the final destination and a single overall booking reference tying it together — without needing to collect bags and re-check in between flights.
How Interlining Shows Up in a PNR
When a PNR includes interlined segments, you'll typically see different two-letter airline codes across the flight segment lines:
1.KHAN/ALI MR 2 PK 302 Y 05SEP 1 LHEDXB HK1 2200 0030 06SEP E 3 EK 001 Y 06SEP 2 DXBLHR HK1 0830 1300 06SEP E 4 BA 444 Y 06SEP 2 LHRORD HK1 1500 1730 06SEP E
This itinerary involves three different airlines — PK (Pakistan International Airlines), EK (Emirates), and BA (British Airways) — all tied together as one journey from Lahore to Chicago, with the GDS PNR managing the full trip even though each airline maintains its own internal record for its segment.
Interlining vs. Codeshare — What's the Difference?
These two terms get confused often, but they're not the same thing:
| Term | What It Means |
|---|---|
| Interlining | Two airlines agree to handle connecting passengers and baggage on a multi-carrier itinerary |
| Codeshare | One airline sells seats on a flight actually operated by a different airline, under its own flight number |
A codeshare flight might show an airline code that doesn't match who's actually operating the plane — you'll sometimes see a PNR note like "OPERATED BY [other airline]" to clarify this.
Why Interlining Matters for Travel Agents
- Baggage: Interline agreements usually mean baggage is checked through to the final destination, which is worth confirming and communicating to the client so they don't worry about re-checking bags at a connection.
- Delays and rebooking: If one airline's flight is delayed and causes a missed connection on a different interlined airline, the rebooking process can be more complex than a single-carrier itinerary.
- Ticketing: Interlined itineraries sometimes require specific ticketing procedures depending on which airlines are involved and what agreements exist between them.
Not all airlines have interline agreements with each other. Budget and low-cost carriers in particular often don't interline at all, meaning a missed connection on one of their flights becomes the passenger's own problem to solve — worth flagging to clients booking tight multi-airline connections on no-frills carriers.
Spotting Interlined Segments Quickly
The fastest way to confirm whether a PNR involves interlining is to check whether the airline code changes between segments while the overall trip is clearly one connected journey (same passenger, consecutive dates, connecting cities). A PNR converter that clearly displays each segment's airline and route side-by-side makes this much easier to spot at a glance than scanning raw GDS text.
See Every Segment Clearly
PNRGenius displays each flight segment with its airline, route, and timing clearly laid out — multi-airline itineraries included.
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