Reader Mail : “What’s the difference between a code share & interline?”

This week’s reader mail comes from Annette up in Canada. Annette asks “What’s the difference between a code share and interline agreement between airlines?

Annette, in fact, a code-share and an interline agreement are quite different. I can go into depth, but that really doesn’t help travelers all that much … so I’ll stick with the simpler answers that actually impact you, the person flying where ever it is your headed.

A code-share agreement offers airlines the ability to use one flight, operated by a partner airline’s “metal,” with multiple flight numbers. Passengers on board these flights can accrue frequent flyer program miles, elite qualifying miles and other perks, such as priority check in, boarding, etc.

An example of a code-share flight can be found looking at American Airlines Flight 85, the 2:55pm flight from New York’s JFK to San Francisco International Airport.  AA Flight 85 also operates as Qantas Flight 3087, Malev Flight 4148, and Alaska Airlines Flight 1288.  All of these flights board an American Airlines Boeing 767-300…but the boarding passes for passengers simply have different flight numbers.

For those loyal to Alaska Airlines flying this route … then can also fly at 3:35pm on Alaska Flight 5534, which is operated on a Delta Air Lines flight, Delta Flight 141 … that is also operated as KLM Flight 8440.  Much like AA 85, Delta 141 flies out on a Delta Boeing 757-200, but passenger-boarding passes just have different flight information.

Code-shares generally happen within an alliance, but not always, such as Air France, a SkyTeam airline, and Qantas, a OneWorld airline.  For routes between France and Australia the two airlines operate code-share flights. For the first leg of the travel, from France to Singapore passengers board an Air France Boeing 777-300ER, flying as Air France Flight 256, which also operates as Qantas 3978. From Singapore to Sydney the passengers then board a Qantas Boeing 747-400, flown as Qantas Flight 6 with the code-share flight number of Air France Flight 8096.

Interline agreements allow passengers to book multiple segments on multiple airlines, and baggage to transferred between airlines.  While interlining is fairly common among ‘legacy airlines’ it is quite rare among low cost carriers, although some low cost carriers are entering into limited interline agreements.

When a passenger purchases a multiple segment, multiple airline, ticket, generally the ticket is issued under the name of the first airline in the sequence of flights. Some travel agents might choose to have the ticket under the name of an airline operating a different segment due to a higher commission for the sale of the ticket.

When a passenger flies an interline flight their baggage will move from flight to flight with them and when they check in for the first flight, it means they’ve also checked in for all the flights.

It is important to note that flying interline flights does not mean that passengers will accrue frequent flyer miles. Agreements such as the recent interline between JetBlue and American Airlines, to move US domestic passengers on JetBlue to American Airlines international destinations, while convenience for flyers, earns no AAdvantage miles on the JetBlue segment or TrueBlue points on the American Airlines segments.

So, while code-sharing and interline flights may sounds the same … in reality the definition of both is quite different.

Hope that clears up the difference between a code-share agreement and an interline agreement.

Happy Flying!



  1. Hey Fish, you are right, those code sharing flights are a boon to Frequent Flyer plans, but they can also backfire on you, especially for us corporate travelers.

    I have found, at least with AA, that booking the flight with the partner airline can actually result in NO Frequent Flyer points, even though you are booked with the partner AND on the AA aircraft. Here is the example:

    You book a flight from JFK to LHR, on an AA flight. However, your corporate travel department gets a better rate on that flight via British Airways, than via AA. So, you get a code share ticket on BA XXX, vs AA YYY. This seems ok, because BA is an AAdvantage partner. BUT, because AA offers this same flight, it does not qualify for AAdvantage points, and you now collect no points for this flight ( which typically will be on a Sunday morning, the way these things go!)

  2. Chip

    There is only one major flaw in your example, American Airlines and British Airways are specifically barred from having code-shared flight across the Atlantic. The ban on these two airlines specifically code-share on transatlantic (TATL) extends to their frequent flyer programs as well. This ban on frequent flyer mileage accrual is particularly problematic, as it really prevents a lot of American Airlines flyers from getting to know BA and blocks many BA flyers from getting to know AA.

    As the AA-BA-IB joint-venture comes into the picture in the next few months, what should be an easy slam dunk for frequent flyers know their preferred carriers partners will require a learning curve, rather than a natural transition.

    Happy Flying!


  3. …and a lot of Code-share airlines do not permit you to use the lounges, which is a bummer when you have flown a long way and just want to relax in the lounge with a cold drink or shower.

  4. Hillary,

    This is true if flying a code-share outside your primary airline’s alliance, such as the Air France-Qantas code-share between France and Australia. You get frequent flyer miles as a Flying Blue member, but Flying Blue Elites cannot use the Qantas lounge … and vise-versa.

    Happy Flying!


  5. Hello Fish,

    Thank you for your explanation of codeshare and interline. I got another question regarding to that. Could you please tell me the difference between interline and strategic partnership (e.g. QF and EK)? Are they the same?


  6. Thank you for sharing your knowledge! I have been searching for the difference between code share and interline flights and you were the only one who gave me an understandable answer. Cheers!

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