Airbus plans to bring forward by six months the entry into service of its revamped A320 jetliner, seen as key to battling Boeing and fending off emerging rivals in the largest aircraft segment.

The fuel-saving model of Airbus’s best selling aircraft will now be available in October 2015, Airbus said in a statement, citing more than 300 provisional commitments or orders for the plane since plans for the A320neo were announced Dec. 1.

The A320neo is an upgraded version of the best-selling 150-seat Airbus jet and promises airlines 12-15 percent in fuel savings from more efficient engines.

Airbus is doing its best to keep up momentum for the aircraft while its rival Boeing mulls a bolder new version of its 737 narrow body jet, but many analysts say airlines will wait to see what Boeing decides before choosing which to buy.

Airbus noted strong sales of a Pratt & Whitney engine, the PW1100G geared turbofan, and named it as “lead development engine” in factory testing for the A320neo.

“We’ll be ready,” Pratt & Whitney spokeswoman Katy Padgett said of the accelerated launch date.

The A320 and 737 compete in the largest segment of the aircraft market worth an estimated $1.7 trillion over 20 years.

The CSeries being built by Canada’s Bombardier leads a field of newcomers also aiming to grab a slice of that market, which also includes China’s C919.

The leap forward in fuel-saving technology of the the Pratt & Whitney engines is driving the next big wave of industry decisions as oil prices remaining above $100 a barrel threaten the viability of many airlines.

Pratt’s fuel-efficient engine has outsold one designed by General Electric and Safran joint venture CFM International.

Shares in Pratt & Whitney parent United Technologies rose 0.2 percent, in line with the U.S. market.