WASHINGTON — Before moving into operational testing, the joint strike fighter will have to prove its mettle as a close-air support plane to the Pentagon’s independent testers, the F-35 program head said Wednesday.

This April, the Defense Department’s director of operational test and evaluation will scrutinize the F-35’s close-air support and reconnaissance capabilities during a series of flights at Edwards Air Force Base and the Point Mugu Sea Range in California, said Vice Adm. Mat Winter, who leads the F-35 Joint Program Office.

Winter said he isn’t sure whether the close-air support assessment in April — the second increment of tests ahead of this September’s initial operational test and evaluation, or IOT&E — would include the much-hyped F-35 versus A-10 flyoff. But it’s coming soon.

“I have not seen the scope of increment two, so I cannot go on record to say that it’s in increment two,” he told reporters during a roundtable Wednesday. “It will be in either increment two or in the formal [IOT&E], and it will be executed.”

As part of the fiscal year 2017 Defense Authorization Act, Congress included language that mandated comparison tests between the F-35 and A-10 Warthog. That assessment is to be overseen by the Pentagon’s independent weapons testing arm, known as the Office of the Director of Operational Test and Evaluation or DOT&E, and will evaluate the F-35’s aptitude in the close-air support, combat search and rescue, and forward air controller airborne missions.

The provision was championed by Warthog supporters on Capitol Hill who said a flyoff would prove the F-35 is not able to fully replace the A-10, which was purpose built for the close-air support mission and has been in use since the 1970s.

Meanwhile, proponents of the F-35 program assert that the Warthog — with its notoriously huge 30 mm GAU-8 Avenger Gatling gun and ability to fly slow and low over the ground — simply accomplishes the close-air support mission differently than the F-35, and that there will be environments where the F-35 is a better fit.

“Just like every other fourth- or four-plus generation fighter, [the A-10] would not likely survive a single mission flown against the anti-access/area denial threats of today. That is where the F-35 was designed to operate,” John Venable, a former F-16 pilot and defense expert at the Heritage Foundation, wrote in an op-ed for National Defense Magazine last year.

The prospect of an F-35 versus A-10 flyoff has been built up over the past several years, however, it’s possible the assessment results in less commotion than expected. Much has changed since fiscal 2017, when the Air Force still wanted to retire the A-10 and was forbidden from doing so by Congress. In fiscal 2018, the service opted to retain the A-10 and is now in the process of rewinging the fleet, putting the future of the Warthog into a much safer position.

The full “increment two” test plan has not yet been approved by Robert Behler, the Pentagon’s director of operational test and evaluation. However, Winter said the scope of the assessment will include weapons drops, engagement with forward air controllers who call in air strikes and armed reconnaissance missions.

The DOT&E Office has already wrapped up the first increment of pre-IOT&E tests, which looked at the F-35’s performance in cold weather environments. It evaluated “the suitability and effectiveness” of a series of F-35 alert launches that took place in late January through early February at Eielson Air Force Base in Alaska.

After the close-air support assessment has wrapped up, the data from both increments of tests will be formally reviewed by DOT&E before the aircraft moves into operational tests this fall. Winter expects IOT&E to wrap up in May 2019.