Shanghai: Chinese budget carrier Spring Airlines said Thursday it plans to buy 60 Airbus aircraft from the A320 single-aisle jetliner family, in a deal valued at $6.3 billion based on list prices.

The order includes 45 A320 planes and 15 A321 aircraft, all with the fuel-efficient new engine option, according to a Spring Airlines statement to the Shanghai stock exchange.

China, the world’s second-largest economy, is already Asia’s biggest aircraft buyer as a growing middle class takes to the skies in ever-increasing numbers.

The Shanghai-based airline said the deal, which was signed on Thursday, sets delivery of the planes from 2019 to 2023, according to the statement.

In July, Spring announced plans to buy 21 Airbus A320 planes for 12.45 billion yuan ($1.9 billion), citing growth in both international and domestic air travel, for delivery from 2015 to 2017.

US aircraft maker Boeing, a rival of Airbus, estimates China will add 6,330 new aircraft worth $950 billion to its commercial fleet by 2034.

Spring Airlines began operations in 2005 and flies more than 90 domestic and international routes, according to its website.

Its Shanghai-listed stock closed up 4.85 percent on Thursday, before the statement was released.