F-35 activities planned to take place after the program’s development phase ends in 2016 could slip by up to six months, according to U.S. Air Force Lt. Gen. Christopher Bogdan, program executive officer for the stealthy fighter.

Work leading up to completion of development of the multinational, $398 billion program is largely on track, he told an audience hosted by Credit Suisse/McAleese & Associates Feb. 25. “I’m measuring the days I’m off in those milestones by days and weeks,” he said.

The Marines are slated to declare initial operational capability with the F-35B, optimized for short-takeoff and vertical landing, as early as June 2015, with the U.S. Air Force to follow as early as August 2016. Both require the 2B software while only the Air Force is awaiting delivery of new processing hardware with the 3i package for its declaration. Thus, if such a delay does take place, it will have the most dramatic effect on the Navy, which is slated to declare IOC as early as August 2018.

Bogdan’s warning is twofold. A potential choke point in testing the software is what is concerning him. In the 3F package, Lockheed Martin is required to deliver an unprecedented level of fusion among various data feeds for the aircraft. Among them are inputs from offboard sensors, including other aircraft and satellites.

Even if the 2B/3i work is finished as planned, Bogdan is worried that the time it takes to outfit the test aircraft, labs and simulators with the new 3F software will eat into time needed to actually test it. This was a concern pointed out in the fiscal 2013 testing report provided to Congress by Michael Gilmore, the Pentagon’s chief tester.

But it is the “complexity of the software that worries us the most,” Bogdan says. “Software development is always really, really tricky,” he says. “We are going to try and do things in the final block of this capability that are really hard to do.” Among them is forming software that can share the same threat picture among multiple ships across the battlefield, allowing for more coordinated attacks.

Meanwhile, Bogdan says the latest software release for the Autonomic Logistics Information System (ALIS) has addressed some of the data shortfalls of the earlier version; these forced maintainers to handle too much information manually, resulting in excessive time to turn around sorties of the single-engine jet.

Previous adds to ALIS were taking “one step forward and two steps back,” he said. “This time we took a step forward and didn’t take a step back.”

However, shortcomings with ALIS are prompting Bogdan to consider overturning an earlier decision that restricts maintainers from releasing a jet for duty without concurrence from ALIS, which handles all parts, system diagnostics and mission planning for the fleet. The feature is at times allowing for errant holds on sorties. “It is not the font of all knowledge about the airplane” as expected, Bogdan says.

“Do we need to start doing that [and allowing maintainers an override]? Yeah, we have to start thinking about doing that … in a measured way,” he says. This is possible because the maintainers have been training with the aircraft for three years, giving them a level of expertise needed for such a measure.