Codeshares let airlines widen their networks, but one flight can carry several flight numbers, which can confuse passengers. UK law therefore puts information duties on everyone who sells the seat, including travel agents.

The duty to name the operating airline

• At booking, the passenger must be told which airline will operate the flight. If that is not yet known, the likely airlines must be named, and the passenger told once it is known.

• If the operating airline changes after booking, the passenger must be told as soon as possible and in any case at check-in, or at boarding for a connecting flight with no check-in.

• The duty must appear in the seller’s general terms of sale.

• A ticket seller is not responsible if it was not told who the operating airline is.

Failing to comply is a criminal offence, subject to a defence of having taken reasonable steps.

Example: an agent sells a connection shown under one airline’s flight number but operated by its partner. The agent must tell the customer at booking which airline actually flies it.

Worth knowing

• Compensation for delays and cancellations under UK passenger rights law is owed by the operating airline, not the marketing airline.

• Baggage allowances on codeshare flights often follow the marketing airline’s rules, so check before you quote.

• GDS displays must show clearly which airline actually operates each flight.