Two quotes:<p><i>The reasoning, explained at Aviation Week,</i> was that Lockheed Martin couldn&#x27;t put together enough units [F-35s - gvb] in that configuration <i>to run the Block 2B OUE in time.</i><p><i>The Block 2B tests were also impacted by restrictions imposed after a June 2013 engine failure in an F-35A unit. That impacted software tests, because the restricted flying hours “reduced the number of accessible test points”.</i><p>It looks like there are not enough F-35s in the correct configuration to run the tests. Unfortunately, this is typical of all programs I&#x27;ve been involved in in my career - software development gets starved for hardware and software test gets screwed over for lack of both hardware and software. The reason is simple: hardware is first in the timeline, software is second and gets hammered by hardware slips, and test is last and gets nailed by both hardware and software slips.<p>Nowadays, software can make a lot of progress on surrogate development systems, but software&#x2F;hardware integration and software&#x2F;hardware test still requires real hardware.