The Defense Department said Friday the Marine Corps’ F-35B variant will reach initial operational capability (IOC) by December 2015, while the Air Force’s F-35A variant will follow a year later and the Navy’s carrier variant  is set to reach the milestone by February 2019.

Congress directed the Air Force and Navy secretaries to provide a report by Saturday that details the IOC dates for the three variants of the Joint Strike Fighter. DoD said in a statement the Air Force, Marine Corps and Navy will achieve IOC once they acquire enough aircraft to establish one operational squadron with enough trained and equipped personnel to support the various missions prescribed by each service.

Underside view of an Air Force F-35A. Photo: Lockheed Martin.

Air Force Lt. Gen. Christopher Bodgan, DoD’s F-35 program executive officer, said Friday in a statement the IOC announcement demonstrates the services’ confidence in the F-35 program and the capabilities it will bring the warfighter.

“I believe the aircraft design and technological capabilities of the F-35 are sound and the Joint Program Office will deliver on our commitments to meet service timelines,” Bogdan said.

Lockheed Martin [LMT] spokeswoman Laura Siebert said Friday in a statement the company appreciates the confidence expressed by the services in the F-35 program and that its top priority is to continue to execute its plan to support these IOC dates. Lockheed Martin is developing the F-35 with subcontractors BAE Systems and Northrop Grumman [NOC]. Pratt & Whitney, a division of United Technologies [UTX], makes the engines.

The Marine Corps’ expeditionary and crisis response force requirements for its December 2015 IOC milestone include an operational squadron with at least 10 aircraft that are capable of performing the prescribed missions of close air support, offensive and defensive counter air operations, air interdiction, assault support escort and armed reconnaissance. DoD said this squadron must also be staffed with Marines properly trained and equipped to execute these missions.

The Navy’s F-35C aircraft carrier variant is distinct from the Air Force’s F-35A conventional variant and the Marine Corps’ F-35B short takeoff and vertical landing (STOVL) variant. The F-35C has larger wing surfaces and reinforced landing gear, features that are used to withstand catapult launches and deck landing impacts associated with the aircraft carrier environment. The F-35C is undergoing flight testing and evaluation at Naval Air Station Patuxent River, Md., before fleet delivery.

A Navy spokeswoman said the service’s timeframe comes later than the other two because it plans to go to IOC at a higher block upgrade.

The announcement on the IOC schedules comes more than a week after the Pentagon, for the first time in the history of the Joint Strike Fighter, reported that overall program cost has gone down from previous estimates. The “select acquisition report,” which covers major programs, said the cost to procure 2,443 of the aircraft has dipped from $395.7 billion to $391.2 billion. It was a good sign for a program facing heavy criticism for massive cost overruns and delays.

The DoD Select Acquisition Report (SAR) released in late May showed a $4.5 billion decrease in the F-35 program, lowering its total procurement cost from $395.7 billion to $391.2 billion (Defense Daily, May 28).

The Air Force is wrapping up a series of “night flights” on all three variants that test the F-35’s capability when flying in instrument meteorological conditions–when pilots have no external visibility references. The Air Force is also planning its first Advanced Medium Range Air-to-Air Missile (AMRAAM) launch in June and will continue with Joint Direct Attack Munition (JDAM) GBU-31 and GBU-12 Paveway II laser guided munition separations (Defense Daily, May 31).

Lockheed Martin said the F-35B STOVL variant in early May completed its first ever vertical takeoff, a significant milestone for the Marine Corps variant, which has been beset with cost overruns and delays. Earlier this year, the F-35Bs were grounded following the discovery of a faulty fueldraulic line, which lies in the vectoring propulsion system specific to the STOVL version (Defense Daily, May 21).