In the Department of Defense's budget request for 2017, the Air Force has conceded what to many has been obvious—that the F-35 Joint Strike Fighter will not be ready to take the place of the A-10 Thunderbolt II (also known as the "Warthog") in close air support missions any time soon. In its budget request, the Air Force is seeking funds to keep the A-10 flying, and DOD officials say the aircraft will remain in service until at least the 2022 fiscal year.

Defense Secretary Ashton B. Carter gave a summary of the budget request in a speech at the Economic Club of Washington, DC on February 2. He said that the A-10 would be replaced by the F-35 squadron by squadron as the new aircraft are brought into service. But the Air Force has also reduced the number of F-35A aircraft it plans to purchase in 2017.

Officials at the Air Force's F-35 Joint Program Office had suggested last year that a "block buy" of F-35 aircraft, possibly in 2018, would reduce the overall cost of the program. But that idea is being opposed by the Defense Department's chief of systems testing. Michael Gilmore, the DOD's Director of Operational Testing and Evaluation (OT&E), has warned against committing to a "block purchase" of the F-35 by the US and other military customers until after the aircraft passes its initial operational test and evaluation.

In a December memo, Gilmore detailed a number of concerns about the F-35 program. He recently reiterated those concerns in his annual report to Congress, released this week. Gilmore wrote, "Is it appropriate to commit to a 'block buy' given that essentially all the aircraft procured thus far require modifications to be used in combat? Although still officially characterized as low-rate, F-35 production rates are already high. Despite the problems [detailed in the report], F-35 production rates have been allowed to steadily increase to large rates, well prior to the IOT&E and official Full-Rate Production (FRP) decision."

About 340 F-35s are expected to be built before the 2017 fiscal year—while the aircraft is still in developmental testing—and a total of over 500 are expected to be built at the current rate before formal acceptance of the F-35 for "full rate production" in 2019.

"These aircraft will require a still‑to-be-determined list of modifications in order to provide full Block 3F combat capability," Gilmore noted. "However, these modifications may be unaffordable for the Services as they consider the cost of upgrading these early lots of aircraft while the program continues to increase production rates in a fiscally constrained environment. This may potentially result in left-behind aircraft with significant limitations for years to come."

Putting down money for a "block buy" before problems with the F-35 are fixed, he suggested, would run contrary to the Obama administration's "fly before you buy" approach to acquisition—and might reduce the incentive for Lockheed Martin to fix the problems sooner.

"Would committing to a 'block buy' prior to the completion of IOT&E provide the contractor with needed incentives to fix the problems already discovered, as well as those certain to be discovered during IOT&E?" he asked, rhetorically. "[Or] would it be preferred—and would it provide a strong incentive to fix problems and deliver fully combat-capable aircraft—to make the 'block buy,' as well as any additional increases in the already high annual production rate, contingent upon successful completion of IOT&E?"