International Airlines Group will today launch Level, a new low-cost trans-Atlantic carrier.
The inaugural flight has left Barcelona and will arrive into Los Angeles at 19:55 completely full, with 314 passengers on board a new Airbus A330.
New routes from Spain will also be added to San Francisco, Buenos Aires and Punta Cana in the Dominican Republic as the airline rolls out in the coming weeks.
Fares start from £99 one-way and have been on sale since March.
More than 100,000 tickets have been sold so far, with IAG seeking to capture part of a rapidly developing market.
With low-cost rival Norwegian leading the way, adding more cheap flights across the Atlantic, IAG has been forced to act.
IAG chief executive, Willie Walsh, said: “We are enabling many people to fly long-haul for the first time and stimulating demand by providing them with more choice.
“Level is breaking the mould.
“We will continue to offer amazing fares.
“Customers can chose add-ons for their flight from a menu of options.
“This is just the start.
“In summer 2018 we will have more aircraft and will operate more destinations from Barcelona.
“We are also planning to expand Level operations to other European cities.”
The pricing structure at Level is divided into six types of fare, with the most basic including hand luggage only.
The most expensive, flexible premium economy, offers a hot meal, two checked bags, and seat selection.
The carrier will start out with flight and cabin crew from its sister airline Iberia and will create up to 250 jobs based in Barcelona.
IAG also owns British Airways, Aer Lingus and Spanish carrier Vueling.
While Norwegian has made the most of the new opportunities offered by the Boeing Dreamliner, Level has taken a different tack.
IAG will operate latest Airbus A330 aircraft on the new routes, with the aircraft designed specifically to compete with the Dreamliner.
Level will fit the plane with 293 economy and 21 premium economy seats.