F-35 Locked and Loaded with Improved Block 3i Software
The F-35 Joint Programme Office (JPO) has stabilised a glitch-prone combination of software and hardware called Block 3i, potentially clearing the way for the US Air Force’s first Lightning II combat squadron to declare initial operational capability (IOC) between August and December.
F-35 manufacturer Lockheed Martin has been preparing the software load in parallel with the Block 2B configuration that the Marine Corps' first operational F-35B group declared war-ready status with last July.
Developmental flight testing of Block 3i started in May 2014. However, problems caused by re-hosting “immature” Block 2B software and capabilities on new computer processors installed in Block 3i aircraft caused flight testing to be restarted in September 2014 and then again in March 2015, reports the Pentagon's top weapons tester.
Developmental flight testing of Block 3i was then terminated last October and an initial version was released to F-35 units “despite unresolved deficiencies” to prevent wider schedule delays.
The programme office has been grappling with “software stability” issues ever since. Aircraft were reportedly having to shut down and reboot on the tarmac or reset a sensor system or radar "once every 4h". That is an unacceptable failure rate for an operational squadron and significantly worse fault rate compared to earlier Block 2B aircraft, which were only having to reboot once every 30h or more.
F-35 programme director Lt Gen Christopher Bogdan told Congress last month that a failure rate of once every 8-10h or greater would be more acceptable, and recent fixes now seem to have achieved that goal.