What exactly are codeshare flights, and how do they operate?

You might have checked the departure board for your flight and confirmed the time, destination, and gate, yet noticed the flight number is different from the one you originally booked.

You could have made a reservation on Delta Air Lines' site with a Delta flight number, but when you arrive at your gate, it turns out to be an Air France or KLM flight.

What’s the reason for this? You might be on a codeshare flight.

Here’s what you should understand about the existence of codeshare flights and their implications for travelers.

What exactly are codeshare flights?

Codeshare flights represent partnerships between airlines, where two or more airlines collaborate on the same flight. In this arrangement, one airline operates the flight (known as the "operating carrier"), while others can promote and sell tickets for that flight using their own airline codes and flight numbers (referred to as the "marketing carriers").

You might come across the phrase that Airline B is going to "add their code" to some of Airline A's flights. This signifies the initiation of a codeshare agreement.

What is the purpose of codeshare agreements?

• Travelers gain access to a wider range of destinations without needing to book separate tickets. Not every airline can fly everywhere due to factors like government regulations, aircraft availability, or airport slots. Airlines may be hesitant to enter untested markets, and codeshares provide a low-risk method for them to expand their offerings to customers and loyalty members.
• If your preferred airline doesn’t serve the country you wish to visit, it might still offer you a codeshare flight there, allowing you to book through your familiar airline. This way, you don’t have to remember multiple airline codes — your entire multi-leg journey can be booked under a single airline code with your favorite carrier.
• Travelers benefit from simplified booking, easier connections, and more coordinated services, including check-in and baggage handling. When the operating airline has different baggage policies from the marketing airline, the marketing airline's policy typically applies since you booked the flight under their code.
• If you hold elite status with the marketing airline, you can usually enjoy those benefits on a codeshare flight booked with that airline’s code. Often, codeshares involve alliance partner airlines, so you might already receive status perks. However, certain benefits, like space-available upgrades through your status, may not be acknowledged by the operating airline if they don’t offer the same to their elite members.
• Codeshares enable airlines that aren’t in the same alliance to provide seamless connections and partnership advantages. For instance, Air Canada has codeshare arrangements with Emirates and Etihad Airways, even though neither airline is part of the Star Alliance. This collaboration allows you to earn and redeem Aeroplan points on Emirates and Etihad flights.

How do codeshare flights function?

You can book a flight from Newark Liberty International Airport (EWR) to Frankfurt Airport (FRA) via United Airlines’ website. This flight is assigned a UA flight number (UA8838), but the booking page indicates that Lufthansa is the operating carrier for this journey.

In this case, United acts as the marketing carrier for the flight, while Lufthansa serves as the operating carrier. This illustrates a codeshare flight.

You could also book this flight on Lufthansa's website, where it is listed under its flight code, LH403. Although you’re still booking a codeshare flight, this time you are reserving through the operating carrier instead of a different marketing carrier.

The procedure may vary by airline, but if you attempt to check in online (or at the airport) through the marketing carrier's site or counters, you will likely be redirected to the website or check-in areas of the operating airline, which assumes responsibility for your journey.

As you go through security and glance at the departures board to find your flight's gate, you might notice various flight numbers displayed. For instance, this Lufthansa flight could show the LH number (for the operating carrier), the UA codeshare number, and possibly another marketing carrier's code, like LX (Swiss Airlines).

All these codes correspond to the same flight, showcasing the various codes under which it has been marketed and sold, ensuring that all passengers, regardless of their booking method, know the correct gate for boarding.

As you board the flight, you may hear announcements welcoming passengers from specific partner airlines — these are likely the marketing airlines that sold seats for this flight through a codeshare agreement.

For travelers, it's wise to check whether a flight is a codeshare when booking to set the right expectations. This is important because different airlines provide varying experiences, from seating to food and drink options to service levels. For instance, a journey to Germany on Lufthansa's "Queen of the Skies" Boeing 747-8 will differ significantly from a United flight to Europe.

There isn’t a major distinction among airlines in economy class; even premium economy is fairly consistent across the industry.

However, when it comes to business and first class, notable variations can exist between airlines, making it crucial to choose the operating carrier wisely and pay attention to the flight code. For example, American Airlines and Qatar Airways codeshare on routes between the United States and Doha's Hamad International Airport (DOH), with Qatar Airways handling the majority of these flights. If you book through American Airlines and have the option of a flight operated by American versus one operated by Qatar Airways, we believe Qatar's Qsuite stands out as the superior choice.

Regarding premium economy, not all airlines provide this service. If you booked a premium economy itinerary through American that combines flights operated by both American Airlines and Qatar Airways, where the latter are codeshare flights listed under an AA code, keep in mind that since Qatar Airways does not offer a premium economy product, you would be placed in economy class for the flights operated by Qatar.

This could lead to an unwelcome surprise upon boarding.

Conclusion

Codeshare flights are a useful way for airlines to expand their offerings in terms of routes, destinations, and ticketing options for passengers, even if they don’t serve the airport you wish to fly to.

One major advantage is the ease of booking a multi-leg itinerary across multiple airlines using just one airline's website, ensuring you can trust your carrier's ticketing processes, baggage rules, and elite status perks.

That said, it's important to confirm the operating carrier of the flight you're booking so you know what to anticipate when you board.

A complicated four-digit flight number is a strong indication that your flight is a codeshare, operated by a carrier different from the one through which you made the booking.