The Defense Department has completed all F-35 block 3i software mission system testing and intends on delivering the software block to the field by January, according to Pentagon’s F-35 chief.

F-35 Program Executive Officer (PEO) Air Force Lt. Gen. Christopher Bogdan said Wednesday the software block has already been delivered to operational testers “so they can wring out,” or resolve, issues. The F-35’s complicated software has been a significant hurdle to fielding the aircraft as there are more than eight million lines of code on the F-35, more than four times the amount of the F-22.

The F-35 software is divided up into six key software releases, or blocks: 1A/1B, 2A, 2B, 3i and 3F. Block 3i provides the same tactical capabilities as block 2B, but the principal difference between 2B and 3i is the implementation of new hardware like the updated integrated core processor, according to F-35 prime contractor Lockheed Martin [LMT].

Bogdan also said the risk schedule for software block 3F has shrunk from “four-to-six” to “about three-to-four” months. He said he expected the full 3F software capability for the F-35A conventional Air Force variant would delivered to the field by August 2017. Teal Group Vice President for Analysis Richard Aboulafia said Monday risk schedule shrinkage is good news as it implies that the window for potential software difficulties has been reduced.

“That’s a good year before the Navy needs it for IOC (initial operational capability) and a good six months before the (defense secretary) has to certify that the airplane is going to be fully 3F capable,” Bogdan told the House Armed Services (HASC) tactical air and land forces subcommittee. “So I think the risk is working its way down.”

Bogdan said as the F-35 program has finished testing software blocks 2b and 3i, the program will catch up on software development as the rest of the F-35 fleet is transferred over to software block 3F. Software block 3F, the latest block, provides 100 percent of the software required for full warfighting capability, including, but not limited to, data link imagery, full weapons and embedded training. Lockheed Martin said mission systems block 3F software development is 98 percent complete.

Software block 2B provides initial warfighting capabilities, including, but not limited to, expanded data links, multi-ship fusion and initial life weapons. With block 2B, more than 87 percent of the required code for full warfighting capability is flying.

The F-35 is developed by Lockheed Martin with subcontractors BAE Systems and Northrop Grumman [NOC].