The head of the Pentagon’s testing and evaluation department sharply criticized the F-35 program’s schedule for incremental software updates on the high-tech aircraft, calling it “high risk” as the program falls further and further behind schedule. Lockheed Martin’s F-35 Lightning II stealth aircraft is basically a giant, flying computer, and its greatest asset, according to Air Force strategists, is funneling huge amounts of information through that computer to and from the battlefield.