British Airways has ordered 18 new Airbus A350 aircraft in a deal worth $6bn (£3.9bn).
BA's parent company, International Airlines Group (IAG), said it was talking to both Airbus and Boeing about supplying aircraft to its Spanish arm, Iberia.
Rolls Royce, which makes the engines for the new planes, said its end of the deal was worth $1.6bn (£1.04bn).
IAG said the deal was for 18 A350s, plus the option for a further 18.
The order represents a significant coup for Airbus, in a market that is dominated by Boeing's wide-bodied 777.
"This is a blow for Boeing," said Adam Pilarski, senior vice-president at aviation consultants Avitas.
British Airways is also about to take delivery of its first 12 Airbus A380 superjumbos.
Airbus chief executive, John Leahy, said the first of IAG's new A350 aircraft would be delivered by 2018.