FORT WORTH, Texas - The Lockheed Martin F-35 Lightning II fleet recently surpassed 15,000 flight hours, marking a major milestone for the program.

"Flying 15,000 hours itself demonstrates that the program is maturing, but what I think is even more impressive is the fact that operational F-35s accounted for more than half of those flight hours," said J.D. McFarlan, Lockheed Martin's vice president for F-35 Test & Verification. "While the fleet continues to train, we are actively flight testing the software and mission systems that will enable the Marine Corps to declare Initial Operational Capability (IOC) next year as planned."

As of April 7, operational F-35s had flown 8,050 hours while System Development and Demonstration aircraft had accumulated 7,123 flight hours. In 2014, F-35A test aircraft have flown 328 hours; F-35B test aircraft have accumulated 191 hours; and F-35C test aircraft have flown 91 hours. In comparison, operational F-35As have flown 963 hours, while their F-35B and F-35C counterparts have accumulated 1,012 and 98 hours respectively for the year.

The U.S. Marine Corps plans to declare IOC in 2015, while the U.S. Air Force and Navy intend to declare IOC in 2016 and 2018, respectively.

The F-35A/C models are powered by a single Pratt & Whitney F135-PW-100 turbofan engine rated 178 kN (40,000 lbst) with afterburning. The F-35B short takeoff and vertical landing (STOVL) version uses a P&W F135-PW-600 turbofan rated 169 kN (38,000 lbst) with afterburning.

Source: Lockheed Martin