Boeing and United Airlines announced the carrier is expanding its 787 Dreamliner fleet again with a new order for nine 787-9 airplanes, the longest-range member of the super-efficient Dreamliner family. The deal is valued at $2.53 billion according to list prices.

United Airlines says the order reflects its fleet strategy of replacing older widebody jets with new, advanced airplanes such as the 787-9, which can fly farther and use 20 percent less fuel with 20 percent fewer emissions.

The U.S. carrier, which announced a purchase of four 787-9s in July, has now ordered a total of 64 Dreamliners.

The latest deal continues the strong momentum for the 787 Dreamliner family, with net orders now above 100 for the year and just one shy of 1,400 since the start of the program. Nearly half of all 787 customers have returned to place additional orders for the airplane, helping to make it the fastest-selling widebody jet in history.

“The 787 Dreamliner has been so successful in the marketplace because of great partners like United Airlines that have taken the airplane’s unrivaled performance to open new routes and offer passengers a wonderful travel experience,” said Ihssane Mounir, senior vice president of Commercial Sales & Marketing for The Boeing Company.