The Air Force is starting to nail down the F-35 Joint Strike Fighter’s costs-per-flying-hour because the service is getting actual data now that the jet is out of training.

“I think we’re getting to a point where we have a pretty good understanding of costs-per-flying-hour as we will define it in the Air Force, (though) the numbers will be a little different for the Marines and the Navy,” Air Force Chief of Staff Gen. Mark Welsh said Friday alongside Secretary Michael Donley during the service’s State of the Air Force briefing at the Pentagon.

Welsh said getting Lockheed Martin’s [LMT] fifth-generation fighter jet out of a test program is helping clarify what the cost-per-flying-hour will likely be. Neither Welsh nor Donley provided specifics on what the cost is shaping up to be, but Welsh said the figure will be more definitive the more the jet is flown.

“We are now getting actual data that we can track and add into the equation, which will be very helpful for us, I think, and that will get more and more definitive as we fly more and more aircraft,” Welsh said. “(This is) critical for a number of reasons: For funding support, for ally satisfaction and comfort level that the airplane is going to do what it is supposed to do.”

Donley added that the F-35 is transitioning into a more robust training environment and, ultimately, into a deployed environment.

Welsh said before he became chief of staff, Lockheed Martin arranged a briefing with the program’s European partners that discussed sustainment costs. Welsh said the costs per flying hour Lockheed Martin presented weren’t the same as the ones the Air Force presented him in their briefings, but he chalked it up to an unintentional characterization difference. The United States’ international partners are the United Kingdom, Italy, the Netherlands, Turkey, Australia, Denmark, Norway, Israel, Japan and Canada, though Canada is re-considering its involvement in the program due to projected cost overruns.

But Welsh said when took over as chief of staff in August, he directed his acquisition staff and the F-35 program office to sit down with Lockheed Martin, put the numbers side-by-side and figure out exactly what the differences were.

The Defense Department is buying 2,443 F-35s: 1,753 As for the Air Force; 260 Cs for the Navy as well as 340 Bs and 80 Cs for the Marine Corps. The F-35A is the conventional variant, the F-35B is the Marine Corps’ short take off and vertical landing (STOLV) variant and the F-35C is the Navy’s aircraft carrier variant.

Donley also said the Air Force plans to deploy CV-22 tilt-rotor aircraft to Japan, but declined to provide any specifics on where or when they will be sent. Japan was hesitant to allow V-22s to be based in the country after a pair of crashes, which the Pentagon blamed on pilot error (Defense Daily, Sept. 20). The CV-22 is the Air Force’s variant while the Marine Corps version is called the MV-22. The V-22 is developed by a team of Boeing [BA] and Bell Helicopter, a Textron [TXT] subsidiary.