Air Force Lieutenant General Chris Bodgan said software testing in December revealed problems with the jets’ ability to fuse data about threats on the ground when four F-35s were flying at once. As a result, the aircraft had trouble identifying the number of targets.
"We found out that the fusion model sometimes, not all the time, sometimes creates an inaccurate picture for the pilot," Bogdan was quoted as saying by Defense News.
Ongoing corrections and tests mean the final version of the software would not be ready as planned in June.
The Marine Corps, however, still plans to declare its version of the F-35, which can take off and land vertically like a helicopter, ready for initial combat use in July. The branch has decided to use the current software version and modify planned operations accordingly. For example, the Marines could fly two sets of two jets, instead of combining them into a four-jet set.
As a result of the delay, Lockheed is likely to forfeit some of the $300 million in incentive fees linked to development of three separate software packages – 2B, 3I and 3F – for the new warplane, Bodgan said.
"Every bit of their fee in development is incentive fee now. They get none of it if they don't finish 2B, 3I and 3F with full capability, on time," he said, adding that the final version of the 2B software is now expected to be ready in early fall.
The Air Force and the Navy are waiting for two more-advanced versions of the software that would allow pilots to deploy a wider range of weapons and sensors.
The loss of the fees would make only a small dent in sales for the jet’s manufacturer, Bethesda, Maryland-based Lockheed-Martin.
The defense contractor’s sales are forecasted to fall slightly this year from $45.4 billion in 2014, with 17% derived from the F-35, according to a Wall Street journal report. However, the program’s profit margins already trail those of the company’s other military aircraft, such as the F-16.