The U.S. Marine Corps is having to wait years longer and pay billions of dollars more than planned to introduce the stealthy F-35B into service, a milestone now planned by December 2015.

But, the corps is making use of this delay to attack the cost per flying hour (CPFH), refine its 50-year sustainment estimate and craft advanced tactics and procedures in hopes of easing the introduction into service.

The Pentagon's Cost Analysis and Program Evaluation (CAPE) team told Congress in a May report that the F-35A's CPFH would be about $32,000, some $7,000 more than for the F-16C/D it would replace. The report did not include a figure for the F-35B. However, Lt. Gen. Robert Schmidle, Marine Corps commandant for aviation, says both the F-35A and B will are expected to ultimately cost about 10% more than the aircraft they are replacing per hour of operation.

The current CPFH for the B, which is slightly more than that of the F-35A as reported in the May acquisition report, is misrepresentative of how the Marine Corps will actually operate the stealthy, single-engine fighter, owing to inaccurate assumptions behind the calculations, Schmidle tells Aviation Week.

For example, the current figure assumes that the F-35B will be used in its short-takeoff-and-vertical landing mode, optimized for the Marine Corps' use on small-deck amphibious ships, 80% of the time. Using the aircraft in this stressing mode prompts a fuel spike, adding cost to the figure.

In actuality, the F-35 B will operate in this mode “a small percentage of the time,” as aircraft will be rotated for use on land bases, Schmidle says.

Also included in the CPFH is the cost of ordnance projected for use every year by the F-35B. Legacy figures do not include this calculation, he adds. So, the Marines are pushing to take that portion of the cost out of the CPFH figure.

The Marine Corps will be the first operator of the most complex of the three F-35 variants; the B is optimized for short-takeoff-and-vertical-landing (Stovl). This was a design choice made to allow for use of the aircraft with Marine Air-Ground Task Forces from the decks of amphibious ships.

However, Schmidle does not see the specialized Pratt & Whitney engine, using a unique Rolls Royce lift-fan for the Stovl mode, as a reason that the F-35B should cost any more to operate than the A model. “We are not convinced—in itself—that [the engine] will be a reason for a higher cost per flight hour,” Schmidle said last month before the Paris air show. “We think, for example, that the cost per hour of the B variant will be in line with the other variants.”

Marine Corps officials are working with the CAPE and F-35 Joint Program Office to revise the assumptions to more accurately reflect how they perceive “normal” operations for the aircraft. A new CPFH figure could be approved as soon as this fall, when Pentagon procurement chief Frank Kendall reviews the program for its readiness for full-rate production.

In the meantime, the service is working to refine how it will maintain the F-35B, changes that will likely bring the CPFH down. The current estimate presumes a high amount of work being done at a central depot; but it will actually be handled in the field.

The 19% reduction in operating cost for the Bell-Boeing MV-22 tiltrotor is a model for the F-35 flying-hour reduction effort, Schmidle says. Much like the F-35, the V-22 operates both ashore and afloat. And, Marine Corps officials are using the statistics between the different maintenance regimes as a template for crafting estimates for the F-35. “We are increasingly confident that there are more savings to be had out there,” Schmidle says.

The service is already flying aircraft using the limited 2A software release at Eglin AFB, Fla., for pilot and maintenance training, and at Marine Corps Fighter Attack Squadron 121 (VMFA 121), the first operational F-35B unit, at Yuma, Ariz. Though the software fielded is limited–allowing for basic takeoffs, approaches and familiarization flights–the F-35 simulators fielded for training already include the more advanced 3F software package. Lockheed Martin, the F-35 airframe prime contractor, is still working to compete the operational release of various increments of software leading to the 3F, but Schmidle says that what has been included in the simulator is allowing for pilots to begin training and tactics work far beyond the capabilities of the aircraft.

Ultimately, this should ease the transition from initial operational capability (IOC) in December 2015 to a full operational capability (FOC) later with the 3F software, which includes more advanced electronic warfare options and a full weapons suite. “We are designing and flying tactics that we probably won't fly in the airplane [soon] with the simulators,” Schmidle says. “FOC will be a natural extension of what we are doing” now.

Advances in simulator technology have allowed the equipment to evolve from being a tool used to train standard procedures for pilots to support advanced tactics training, because the software is more realistic. Ultimately, 52% of the training syllabus for the F-35B will be handled in the simulator, also reducing the CPFH for the aircraft, Schmidle says.

Two of six planned full-mission F-35 simulators have been installed at Yuma. VMFA 121 officers are now training with it and developing tactics beyond what the fielded aircraft can now do, including simulated use of a range of weapons, including classified weapons, Schmidle says.

The squadron now has eight of 16 F-35Bs. It will permanently move to Marine Corps Air Station Iwakuni in Japan in late summer 2017. Of VMFA 121's 16 aircraft, six are slated for deployment on the USS Makin Island amphibious assault ship in the Pacific, with the remaining 10 at Iwakuni.

“The F-35B will be the multirole, multi-mission fifth-gen aircraft that the nation will have in [the Western Pacific], and it will be the only one in the Department of the Navy,” Schmidle says.

The Marines plan to declare IOC by the end of December 2015 with the 2B software, which has limited functionality. Schmidle, however, says even use of the AIM-120, 1,000-lb. GPS-guided Joint Direct Attack Munition and 500-lb. laser-guided bomb, will allow for anti-air and ground attack missions.