American Airlines, British Airways and Iberia promised a "new deal for transatlantic flyers" as they inaugurated their new joint business October 6.
The airlines, meeting in London, released details of how they expect the joint business to help travelers, promising cheaper fares, a bigger choice of flight times and easier connecting journeys.
All three are existing members of the Oneworld alliance but will see significantly closer integration to compete with other alliances, such as the SkyTeam alliance of Air France-KLM, Delta and Alitalia announced in July.
Four new routes - New York JFK-Budapest, Chicago-Helsinki, London Heathrow-San Diego and Madrid-Los Angeles - will take to the skies from April as an "early benefit of the new joint business."
In time, the airlines expect that increased code-sharing will drive prices down as customers will have a greater number of flights from which to choose if the price offered by the airlines happens to be different.
From summer 2011, schedules will be aligned, spacing out departure times (at the moment, six of the 11 current daily New York JFK-London flights offered by American and BA depart at very similar times) to give customers more flexibility.
Travelers will also be able to book on any of the three airlines' websites and check in at the desk of the airline they booked with or are flying with - allowing a passenger booked on American but flying on a British Airways codeshare to skip a busy American check-in desk in favor of a quieter British Airways one at Heathrow, for instance.
As part of the arrangement, the frequent flyer programs have been aligned, allowing passengers to earn and redeem miles on all three airlines' flights between the USA and Europe.
However, the news hasn't pleased everybody - as several travel bloggers have pointed out, the controversial fuel surcharges imposed by British Airways are payable even on frequent flyer redemptions and can reach as much as $500 (€358) for premium tickets.
The closer integration means that American passengers who want to cash in their miles for a premium flight could pay up to four times as much in taxes and surcharges.