Test pilot Major Charles Trickey fired the first aerial gun burst from the jet's 25mm Gatling gun during an October 30 flight at Edwards Air Force Base, California, the JPO said in a statement.
"It was the first airborne gunfire for the F-35," Trickey said in a video released with the statement. "Just going out there today to make sure the functionality, loads … acoustics – all that stuff worked. And it absolutely did – it went about as smooth as you could have expected on the first flight."
Specifically, three bursts of 30 rounds and two of 60 rounds were fired from the plane's internal, four-barrel gun. It marked the first in a series of flight tests to evaluate the in-flight operation of the weapon.
The gun had already been tested on the ground, with 13 gunfire events over three months, which verified the integration of the gun into the plane, Defense News reported.
According to the JPO, the F-35 gun will be operational in 2017, at the end of the program's system development and demonstration phase.
Made by Lockheed Martin Corp., the F-35 is the Pentagon’s priciest weapons program ever, estimated to cost $391 billion to purchase 2,457 aircraft for the Air Force, Marine Corps and Navy.
The Corps this year declared the F-35B ready for initial operations. The Air Force is expected to follow suit in 2016 and the Navy in 2018.