Interline Agreement: How your bags get transferred across multiple carriers

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So what is an interline agreement?

Simply, an interline agreement allows a passenger to get to a destination using different airlines, change planes, and have a checked bag be on the final baggage claim when they land. This allows airlines to issue a single ticket on different carriers. It’s also how airlines can issue you a ticket in the event of a delay or cancellation on another airline: one they have an interline agreement with.

Passengers don’t pull their hair out and airlines make more $$$

Interlining is helpful to passengers in a variety of ways. Here’s a few

  1. Those who may live in an area that one airline alone doesn’t serve and therefore need two different airlines. Instead of that passenger needing to book two separate tickets, retrieve their luggage and recheck it, they can rest easy knowing their bags will be transferred to the other airline and they can just go to their gate, and get their bag at their final destination.
  2. Award tickets avail from a hub but not your city
  3. Two separate tickets are just cheaper

Interlining is helpful to airlines

  1. They earn more money because their network effectively expands
  2.  They can accommodate stranded passengers with interline partners at pre-negotiated industry prices

United’s Interline info

I always wondered how this worked and was playing around with expertflyer when I came across United’s interline agreement which looks like this: United has one of the most generous interline agreements

Screen Shot 2016-05-19 at 1.17.45 AM Screen Shot 2016-05-19 at 1.17.51 AM

As you can see above, there are two categories that expertflyer shows for United’s interline agreement: E-Tickets they can issue, and Paper ticket/baggage they may check. Maybe you’ve noticed websites like Orbitz, Expedia, etc can sell tickets that will put you on two different airlines. If that first airline is United, then they will have to have an interline agreement with the second airline in order to complete the process. They have interline agreements with most legacy carriers it appears and therefore can check your bag on through to them.

It’s worth noting tho that American has a very limited interline agreement when dealing with separate tickets. They will only check bags on through to American, American Eagle, and One World partners.

Delta has no interline agreements

How could the information on expertflyer be useful?

As mentioned above, I think it to be particularly useful when booking award tickets. Sometimes you need to book a positioning flight in order to get to your main departure city, often a hub.

Singapore 1st Class Moscow

  • Let’s look at this scenario – IAH to DME on Singapore Air – It’s a fantastic value at 57,375 miles ( after the 15% online discount) But you need to get to Houston.
  • Well, United and Singapore are both in Star Alliance so, in theory, this shouldn’t be a problem for the agent to check your bags on through to the Singapore flight, even if you are using two separate tickets. That’s pretty great, especially if you have a quick transfer.
  • However, don’t count on it – a lot of agents either won’t have the know-how or won’t be bothered to sort it out for you.


Here’s the check list.

  1. Make sure that it’s actually possible by double checking on Expertflyer
  2. Cross your fingers and pray that you get a very knowledgable and willing agent
    • it’s completely up to their discretion
  3. Make sure that you are checked in to all flights and have boarding passes for those flights.
  4. Your checked baggage meets the most restrictive requirements for any of the airlines you’re traveling on.
  5. You will pay the bag fees of the origin flight – even if you qualify for waived fees on the connecting flight
    • in the above scenario, Singapore would allow 2 free. United would charge for both if booked into coach for the positioning flight.
  6. If you need to pass through customs on your trip…’America and Australia’ – you still collect and recheck bags.

Lemme know your interlining experiences.



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1 Comment

  • Porcelain Tile Traveler November 21, 2016

    This is horrible….now everyone traveling on 2 tickets is really screwed. The catch-22 is after you get your 2 large bags, you have to travel to another terminal. And the terminal train doesn’t allow metal carts… how is someone traveling international packed with 2-3 large bags and all their carryon going to do it? I asked a domestic carrier and they said get a skycab. And then tip them $50 or so. This is fine and might work in theory, but I bet finding a skycab and it working is going to be slim!

    I just don’t get this….it is a horrible policy. I wouldn’t even mind a fee of $x per bag.

    Most of us live in a non-gateway city…..and must buy 2 tickets.

    And last I checked in Feb 2016, Singapore Airlines had no domestic USA airline that would pass the bags to them on 2 tickets….even the Star Alliance carriers. So really double and triple check answers here. In Feb, I was getting mixed answers. I even flew Cathay and booked United because I was told they would pass the bags….but when I got to airport, it was not so. I got to Chicago ORD and couldn’t get my bags in enough time….ran to international and had to make a decision to fly without bags or miss flight. I asked the Cathay could they get the bags and send them on next flight and she said no.

    If this changes or someone has new information, I hope people will share……my preference for international is Singapore Airlines, Cathay, and Korean Air ( to my destinations).

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