Block by Block

The first production Joint Strike Fighters delivered by Lockheed Martin are flying Block 1 of the aircraft's software, and Block 2 lab testing began in June as anticipated, a Lockheed spokeswoman tells InsideDefense.com. Block 2 is set to begin flight testing near the end of 2011, according to Lockheed spokeswoman Laurie Quincy.

Inside the Air Force reported today that some of the F-35's internal sensors -- the radar and distributed aperture system built by Northrop Grumman -- are already conducting tests using Blocks 2, 3, and 4 of the aircraft's software in an effort to “reduce risk” going forward. Senior Defense Department officials, including the department's top weapons tester and program cost evaluator, have expressed concern with the JSF's software development in congressional testimony.

The following is the full statement provided to InsideDefense.com by Quincy:

Production aircraft are currently flying with Block 1 software. This software includes more than 6 million lines of code. Additionally, Mission Systems Block 2 software lab testing began in June. This block, which provides the Initial War fighting capabilities, incorporates datalinks, additional electronic warfare (EW) and radar sensor functions, and additional weapons. This software will enter flight testing in the fourth quarter of 2011 and will be delivered with LRIP 4 aircraft in the fourth quarter of 2012.