Icelandair Group HF (ICEAIR.IC) said on Friday it signed a provisional deal to purchase 13 of European planemaker Airbus SE’s (AIR.PA) latest A321XLR single-aisle jet, with deliveries slated to begin in 2029.

As part of the deal, Icelandair has an option to purchase an additional 12 aircraft after buying 13 of Airbus’ newest and largest narrowbody airliner at an undisclosed price.

Icelandair, however, said it plans to start using the world’s largest planemaker’s aircraft from 2025, and is currently in advanced negotiations to lease four Airbus A321LR planes for this purpose.

“With the acquisition of the Airbus aircraft, Icelandair will complete the replacement of the Boeing 757,” the company said in a statement.

Icelandair said it would continue to operate a full Boeing fleet until 2025, after which a mixed fleet of both Airbus and Boeing planes will be in operation following the first deliveries from Airbus.

Airbus and U.S. rival Boeing Co (BA.N) have been locked in a dead heat for deliveries in the first two months of the year, but the European planemaker has had a tougher task to meet annual forecasts amid supply woes.

The pair delivered a combined total of 66 jets in January and February. But whereas this makes up some 12% of market forecasts for Boeing’s 2023 deliveries, Airbus has secured just 9% of its 2023 target of 720 jets, below the trend for this time of year.

(This story has been corrected to say ‘signs deal’ instead of ‘orders,’ and to change figure to 13 to exclude options in the headline and paragraphs 1 and 2)