British Airways has ordered 18 new Airbus A350 aircraft as part of a move to phase out a fleet of 30 Boeing aircraft over the next 10 years.
The order, announced by BA's parent company International Airlines Group (IAG), allows for an option of a further 18 A350 aeroplanes.
As well as its new Airbus aircraft, IAG plans to place firm orders on 18 Boeing 787s, which together will be used to replace BA's fleet of 30 Boeing 747-400 planes between 2017 and 2023.
IAG also said it was talking to Airbus and Boeing about supplying aircraft for its Spanish arm, Iberia.
The order for the Airbus A350s will be a welcome boost to Britain's aviation industry.
The aircraft are powered by Rolls-Royce Trent XWB engines, and the deal is worth 1.6 billion US dollars (£1.04 billion), the company said.
Willie Walsh, IAG's chief executive, said: "The A350-1000 will bring many benefits to our fleet. Its size and range will be an excellent fit for our existing network and, with lower unit costs, there is an opportunity to operate a new range of destinations profitably.
"This will not only bring greater flexibility to our network but also more choice for our customers.
"This order will also secure jobs in Britain and Spain. The A350's wings are made in Britain while its horizontal tail plane, horizontal tail plane boxes and lower wing covers are made in Spain. Rolls-Royce Trent XWB engines are assembled in Britain."
The order for the A350 aircraft follows BA's decision in 2007 to buy 12 Airbus A380s, the first of which will be delivered this summer.
"This is an important announcement from one of the world's most respected and influential airline brands," said John Leahy, Airbus's chief operating officer.
"The A380 and the A350 are perfectly matched for greener long-haul operations and demonstrate environmental leadership.
"We are simply delighted that British Airways has chosen the A350 to spread its global wings and its iconic livery."