What is a codeshare — a one-line definition of marketed-by versus operated-by flights, plus how bags, seats and claims usually split between partner airlines.
What is a codeshare?
A codeshare is a single flight sold under one airline’s flight number but flown by a partner airline’s crew and aircraft — so the brand on your booking can differ from the metal you board.
Airlines sell each other’s seats so they can offer more routes without flying every sector themselves. On the ticket you may see a British Airways, United or Qantas number; the itinerary line “operated by” names who actually flies the aircraft. That operating carrier usually decides the seat map, cabin product, carry-on sizer and day-of boarding rules, while the marketing or ticketing carrier often owns the PNR, fare rules and some rebooking paths.
Codeshares are normal alliance and joint-venture plumbing, not a trick by default. Trouble starts when travellers assume the marketing brand’s hard product, elite upgrade certificates or baggage quirks apply 1:1 on partner metal. For the full trap list — bags, seats, lounges and compensation ownership — use the deeper guide codeshare flights explained.
When you compare fares on flight deals, expand every segment and read the operated-by line before you pay. A “nonstop” tile can still be partner metal. alliance reciprocity charts and your ticket’s conditions of carriage for the route you hold.
How does a codeshare show up on a real booking?
You buy Airline A flight A1234; the receipt says operated by Airline B. You sit in B’s seat, often check bags to the ticketed allowance, and may need B’s app for the true seat map — while A still appears as the seller on your confirmation.
Example: a London–New York ticket sold as a BA flight number but operated by American Airlines metal. Club Suite photos on the BA site do not describe the AA cabin you will board. Select seats in the system that controls the aircraft, pack to the tighter carry-on rule, and keep both record locators if two appear. Baggage fee context lives in airline baggage fees compared 2026; cabin brand confusion pairs with basic economy vs economy vs premium.
If the flight is delayed, statutory claims may follow the operating carrier under many UK/EU-style rules, while refunds can still involve the ticketing airline — start with flight delay compensation rights and EU261 complete rules. jurisdiction for your exact itinerary.