Codeshare Flights Explained:
Who's Flying Your Plane and Who's Responsible

You book a flight on British Airways, but your ticket says it's operated by American Airlines. You check in with the wrong airline at the airport. When the flight is delayed, you don't know who to contact for compensation. When you land and try to rebook a missed connection, you're bounced between airlines' customer service departments. Welcome to the confusing world of codeshare flights. Here's what you actually need to know.

What is a codeshare?

A codeshare flight is one where two airlines share the same aircraft and flight number. One airline is the marketing carrier (the airline whose code is on your ticket and the one you booked through), and the other is the operating carrier (the airline that actually owns and operates the aircraft).

Here's a real example: You buy a ticket on BA (British Airways) 8208, but your booking confirmation says "Operated by American Airlines." This means you're sitting on an American Airlines plane with American Airlines crew, even though you bought the ticket from British Airways. Both airlines get a cut of the revenue from your ticket.

The key distinction matters everywhere from check-in to compensation. The marketing carrier is your booking partner — the operating carrier is your actual airline once you're at the airport.

Why codeshares exist

Codeshare flights are driven by three main factors:

Alliance partnerships

Most codeshares come from airline alliances like Star Alliance (United, Lufthansa, ANA), Oneworld (British Airways, American Airlines, Qantas), and SkyTeam (Delta, Air France, KLM). These alliances allow members to put their code on each other's flights, making it appear to customers that they operate more routes than they actually do.

Network expansion

Airlines use codeshares to extend their network cheaply. Instead of buying planes and running routes themselves, they partner with another carrier who already operates that route. British Airways doesn't need to buy American aircraft to fly domestic US routes — they just codeshare on American Airlines' existing flights.

Revenue sharing

Both airlines make money on the same ticket. The marketing carrier gets a percentage of the fare, the operating carrier gets the rest plus operational revenue. It's a win-win for both airlines, though sometimes confusing for you.

Who do you check in with at the airport?

Always check in with the operating carrier — the airline actually flying the plane. This is non-negotiable.

If you board an American Airlines plane, you check in at the American Airlines desk, go through American Airlines security protocols, and follow American Airlines policies. British Airways won't have access to your seat on an American Airlines plane.

The issue is that many passengers check their booking (BA 8208) and walk up to the British Airways desk. British Airways staff will tell you that the flight is operated by American and redirect you. But you've just wasted time you didn't have. Always read your booking confirmation for the operating carrier before you get to the airport.

Who handles rebooking when things go wrong?

This is where codeshares get complicated. The answer depends on whether you're on a single ticket and where you are when you need rebooking.

Single ticket (same booking reference)

If both your flights are on the same booking reference, the marketing carrier's customer service is your first point of contact. They can help you rebook on alternative flights. However, once you're at the airport, the operating carrier is ultimately responsible for handling you and your bag to your final destination.

IATA Resolution 766

Internationally, IATA Resolution 766 sets the standard for what happens when an airline fails to get you to your destination. The key principle: the airline that caused the disruption is responsible for rebooking you. If an American Airlines flight is delayed, American Airlines must rebook you, even if you booked on British Airways.

Practical strategy

Here's what actually works in practice: Go directly to the operating carrier's desk at the airport with your bags ready. Simultaneously, call the marketing carrier's helpline and tell them you need rebooking. The operating carrier can rebook you on their own flights faster. The marketing carrier can route you onto partner airlines if necessary. One of them will get you on the next available flight. You're playing the system correctly when you're not waiting for a single phone call to sort everything out.

Baggage on codeshare flights

This is where codeshare rules get truly confusing. Multiple airlines are involved, so which airline's baggage policy applies?

IATA 302: The Most Significant Carrier (MSC)

The answer is IATA 302, an international standard that determines baggage allowance based on the Most Significant Carrier. The MSC is defined as the marketing carrier of the flight that crosses an IATA global area boundary (basically, the longest segment of your journey).

Example: You're flying from New York to Tokyo on a codeshare ticket. BA is your marketing carrier, but JAL (Japan Airlines) is operating. Which baggage rules apply?

• If BA is the marketing carrier of the longest segment crossing IATA boundaries, BA baggage rules apply
• If JAL is the marketing carrier of the longest segment, JAL baggage rules apply
• If you have multiple codeshares (BA to Frankfurt, then Lufthansa to Tokyo), you check which single flight crosses the most significant boundary

The problem: the same physical flight with different codes can have different baggage allowances. Your friend sitting next to you on an American Airlines plane might have a 23kg baggage limit (because they booked on American), while you have 20kg (because you booked on British Airways). The operating carrier is the same, but your booking codes are different, so different MSC rules apply.

Compensation on codeshare flights

When a codeshare flight is delayed or cancelled, who pays compensation? Again, it depends on which regulation applies.

EU261 (European Union)

EU261 applies based on two factors: (1) the departure airport is in the EU, OR (2) the operating carrier is EU-based. If either is true, you're covered. This is important: if you fly from London (EU) on a US-based operating carrier, EU261 still applies. If you fly from New York on a EU-based operating carrier, EU261 still applies.

Compensation under EU261 is up to €600 per person for delays over 3 hours, depending on flight distance. The operating carrier is generally responsible for paying, but if that carrier is bankrupt or disputes the claim, you can claim against the marketing carrier.

UK261 (United Kingdom)

Similar rules apply for flights departing from UK airports (post-Brexit). You're covered if you depart from the UK OR fly on a UK-based operating carrier.

Who to file with

File compensation claims with the operating carrier first (they're the ones legally responsible). If they refuse or ignore you, escalate to the marketing carrier. Both can be held liable under EU261/UK261. Some of the best practices: submit your claim simultaneously to both airlines' customer service, use registered mail or email, keep all documentation, and be prepared to escalate to a small claims court or ombudsman if needed.

How to identify codeshares

Before you book, look for these red flags:

• "Operated by" text: If your booking confirmation says "Operated by Airline X," you're on a codeshare. Read it carefully.
• Different flight codes: You searched for BA8208 but got a booking with BA8208 (BA code) operated by AA (American code). The codes don't match? Check the operating carrier.
• Unexpected baggage allowance: You booked on an airline that normally gives 23kg but your confirmation shows 20kg. You're likely on a codeshare where another airline's rules apply.
• Different check-in location: Your booking app says to check in with Airline X, but you booked Airline Y. Codeshare.

Practical tips for codeshare flights

• Check the operating carrier before booking. If you have flexibility, avoid codeshares. Direct flights with a single airline are simpler. If you must book a codeshare, confirm which airline's customer service will be your contact.
• Verify baggage rules for your specific booking. Don't assume the operating carrier's standard policy applies. Check the MSC rules for your route.
• Seat selection may be limited. Some codeshares (especially international ones) restrict seat selection on the marketing carrier's website. You might have to wait until 24 hours before departure or choose seats with the operating carrier instead.
• Frequent flyer miles credit to the marketing carrier. If you're collecting miles, they go to the airline you booked, not the one flying the plane. Book on the airline whose program benefits you most.
• Save the operating carrier's contact info. Write down the operating airline's customer service number and email. If something goes wrong at the airport, you'll need them immediately.
• For missed connections: Go directly to the operating carrier's counter, not the marketing carrier. You need to be rebooked on the next available flight immediately, and the operating carrier can do that faster than a phone call to the marketing carrier's call center.

The bottom line

Codeshare flights are revenue-sharing partnerships that confuse responsibility. Remember: the marketing carrier is your booking partner, the operating carrier is your actual airline at the airport. Check in with the operating carrier. Rebook through both carriers if something goes wrong. File compensation claims with the operating carrier. And always, always verify baggage allowance for your specific booking code before you pack.

Want to dive deeper into your rights when flights go wrong? Use our connection time calculator to find safe layover times for any airport, or read our full recovery guide for word-for-word scripts and legal strategies.