United Airlines Holdings Inc. is near an agreement to purchase a double-digit number of Airbus SE A321 narrowbody jets, according to people familiar with the matter.

An order may be announced as soon as Tuesday, the people said, asking not to be identified discussing confidential negotiations. A deal would add to the 120 A321s United already has on backlog with the European planemaker. Airlines pay about $60 million each for new A321s after customary industry discounts.

United has been loading up on the largest Airbus narrowbody as the airline retires its aging Boeing Co. 757s. The carrier has also ordered Boeing’s rival 737 Max model. United has been one of the largest post-pandemic aircraft buyers and has said it plans to add about 700 narrow- and widebody planes over the next decade.

Carriers across the world are locking in delivery positions for new aircraft, as Airbus and Boeing struggle to keep pace with demand spurred by the post-pandemic rebound in air travel. Backlogs at both planemakers now stretch past the end of this decade.

Representatives for United and Airbus declined to comment.

Author: Mary Schlangenstein, Siddharth Philip and Julie Johnsson